From 9ba559217bea0803263a9a9a0bafcf9203606f5b Mon Sep 17 00:00:00 2001 From: "Madhavan T. Venkataraman" <75220914+madvenka786@users.noreply.github.com> Date: Fri, 5 Mar 2021 10:07:30 -0600 Subject: [PATCH] Static tramp v5 (#624) * Static Trampolines Closure Trampoline Security Issue ================================= Currently, the trampoline code used in libffi is not statically defined in a source file (except for MACH). The trampoline is either pre-defined machine code in a data buffer. Or, it is generated at runtime. In order to execute a trampoline, it needs to be placed in a page with executable permissions. Executable data pages are attack surfaces for attackers who may try to inject their own code into the page and contrive to have it executed. The security settings in a system may prevent various tricks used in user land to write code into a page and to have it executed somehow. On such systems, libffi trampolines would not be able to run. Static Trampoline ================= To solve this problem, the trampoline code needs to be defined statically in a source file, compiled and placed in the text segment so it can be mapped and executed naturally without any tricks. However, the trampoline needs to be able to access the closure pointer at runtime. PC-relative data referencing ============================ The solution implemented in this patch set uses PC-relative data references. The trampoline is mapped in a code page. Adjacent to the code page, a data page is mapped that contains the parameters of the trampoline: - the closure pointer - pointer to the ABI handler to jump to The trampoline code uses an offset relative to its current PC to access its data. Some architectures support PC-relative data references in the ISA itself. E.g., X64 supports RIP-relative references. For others, the PC has to somehow be loaded into a general purpose register to do PC-relative data referencing. To do this, we need to define a get_pc() kind of function and call it to load the PC in a desired register. There are two cases: 1. The call instruction pushes the return address on the stack. In this case, get_pc() will extract the return address from the stack and load it in the desired register and return. 2. The call instruction stores the return address in a designated register. In this case, get_pc() will copy the return address to the desired register and return. Either way, the PC next to the call instruction is obtained. Scratch register ================ In order to do its job, the trampoline code would need to use a scratch register. Depending on the ABI, there may not be a register available for scratch. This problem needs to be solved so that all ABIs will work. The trampoline will save two values on the stack: - the closure pointer - the original value of the scratch register This is what the stack will look like: sp before trampoline ------> -------------------- | closure pointer | -------------------- | scratch register | sp after trampoline -------> -------------------- The ABI handler can do the following as needed by the ABI: - the closure pointer can be loaded in a desired register - the scratch register can be restored to its original value - the stack pointer can be restored to its original value (the value when the trampoline was invoked) To do this, I have defined prolog code for each ABI handler. The legacy trampoline jumps to the ABI handler directly. But the static trampoline defined in this patch jumps tp the prolog code which performs the above actions before jumping to the ABI handler. Trampoline Table ================ In order to reduce the trampoline memory footprint, the trampoline code would be defined as a code array in the text segment. This array would be mapped into the address space of the caller. The mapping would, therefore, contain a trampoline table. Adjacent to the trampoline table mapping, there will be a data mapping that contains a parameter table, one parameter block for each trampoline. The parameter block will contain: - a pointer to the closure - a pointer to the ABI handler The static trampoline code would finally look like this: - Make space on the stack for the closure and the scratch register by moving the stack pointer down - Store the original value of the scratch register on the stack - Using PC-relative reference, get the closure pointer - Store the closure pointer on the stack - Using PC-relative reference, get the ABI handler pointer - Jump to the ABI handler Mapping size ============ The size of the code mapping that contains the trampoline table needs to be determined on a per architecture basis. If a particular architecture supports multiple base page sizes, then the largest supported base page size needs to be chosen. E.g., we choose 16K for ARM64. Trampoline allocation and free ============================== Static trampolines are allocated in ffi_closure_alloc() and freed in ffi_closure_free(). Normally, applications use these functions. But there are some cases out there where the user of libffi allocates and manages its own closure memory. In such cases, static trampolines cannot be used. These will fall back to using legacy trampolines. The user has to make sure that the memory is executable. ffi_closure structure ===================== I did not want to make any changes to the size of the closure structure for this feature to guarantee compatibility. But the opaque static trampoline handle needs to be stored in the closure. I have defined it as follows: - char tramp[FFI_TRAMPOLINE_SIZE]; + union { + char tramp[FFI_TRAMPOLINE_SIZE]; + void *ftramp; + }; If static trampolines are used, then tramp[] is not needed to store a dynamic trampoline. That space can be reused to store the handle. Hence, the union. Architecture Support ==================== Support has been added for x64, i386, aarch64 and arm. Support for other architectures can be added very easily in the future. OS Support ========== Support has been added for Linux. Support for other OSes can be added very easily. Signed-off-by: Madhavan T. Venkataraman * x86: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code mapping and data mapping sizes. - Define the trampoline code table statically. Define two tables, actually, one with CET and one without. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_unix64 - ffi_closure_unix64_sse - ffi_closure_win64 The prolog functions are called: - ffi_closure_unix64_alt - ffi_closure_unix64_sse_alt - ffi_closure_win64_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman * i386: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code table statically. Define two tables, actually, one with CET and one without. - Define the trampoline code table statically. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_i386 - ffi_closure_STDCALL - ffi_closure_REGISTER The prolog functions are called: - ffi_closure_i386_alt - ffi_closure_STDCALL_alt - ffi_closure_REGISTER_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman * arm64: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code mapping and data mapping sizes. - Define the trampoline code table statically. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_SYSV - ffi_closure_SYSV_V The prolog functions are called: - ffi_closure_SYSV_alt - ffi_closure_SYSV_V_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman * arm: Support for Static Trampolines - Define the arch-specific initialization function ffi_tramp_arch () that returns trampoline size information to common code. - Define the trampoline code mapping and data mapping sizes. - Define the trampoline code table statically. - Introduce a tiny prolog for each ABI handling function. The ABI handlers addressed are: - ffi_closure_SYSV - ffi_closure_VFP The prolog functions are called: - ffi_closure_SYSV_alt - ffi_closure_VFP_alt The legacy trampoline jumps to the ABI handler. The static trampoline jumps to the prolog function. The prolog function uses the information provided by the static trampoline, sets things up for the ABI handler and then jumps to the ABI handler. - Call ffi_tramp_set_parms () in ffi_prep_closure_loc () to initialize static trampoline parameters. Signed-off-by: Madhavan T. Venkataraman --- Makefile.am | 3 +- configure.ac | 11 +- include/ffi.h.in | 5 +- include/ffi_common.h | 4 + include/tramp.h | 24 + src/aarch64/ffi.c | 34 +- src/aarch64/internal.h | 10 + src/aarch64/sysv.S | 70 +++ src/arm/ffi.c | 32 ++ src/arm/internal.h | 10 + src/arm/sysv.S | 47 ++ src/closures.c | 47 +- src/tramp.c | 729 ++++++++++++++++++++++++++++ src/x86/ffi.c | 36 ++ src/x86/ffi64.c | 32 ++ src/x86/ffitarget.h | 6 +- src/x86/ffiw64.c | 15 + src/x86/internal.h | 14 + src/x86/internal64.h | 14 + src/x86/sysv.S | 89 ++++ src/x86/unix64.S | 75 +++ src/x86/win64.S | 14 + testsuite/libffi.closures/closure_loc_fn0.c | 3 + 23 files changed, 1316 insertions(+), 8 deletions(-) create mode 100644 include/tramp.h create mode 100644 src/tramp.c diff --git a/Makefile.am b/Makefile.am index 7654bf5..1b18198 100644 --- a/Makefile.am +++ b/Makefile.am @@ -38,7 +38,8 @@ toolexeclib_LTLIBRARIES = libffi.la noinst_LTLIBRARIES = libffi_convenience.la libffi_la_SOURCES = src/prep_cif.c src/types.c \ - src/raw_api.c src/java_raw_api.c src/closures.c + src/raw_api.c src/java_raw_api.c src/closures.c \ + src/tramp.c if FFI_DEBUG libffi_la_SOURCES += src/debug.c diff --git a/configure.ac b/configure.ac index 093b87d..0f141f4 100644 --- a/configure.ac +++ b/configure.ac @@ -67,7 +67,7 @@ AC_CHECK_HEADERS(sys/memfd.h) AC_CHECK_FUNCS([memfd_create]) AC_CHECK_HEADERS(sys/mman.h) -AC_CHECK_FUNCS([mmap mkostemp]) +AC_CHECK_FUNCS([mmap mkostemp mkstemp]) AC_FUNC_MMAP_BLACKLIST dnl The -no-testsuite modules omit the test subdir. @@ -363,6 +363,15 @@ AC_ARG_ENABLE(raw-api, AC_DEFINE(FFI_NO_RAW_API, 1, [Define this if you do not want support for the raw API.]) fi) +case "$target" in + *-cygwin*) + ;; + *arm*-*-linux-* | aarch64*-*-linux-* | i*86-*-linux-* | x86_64-*-linux-*) + AC_DEFINE(FFI_EXEC_STATIC_TRAMP, 1, + [Define this if you want statically defined trampolines]) + ;; +esac + AC_ARG_ENABLE(purify-safety, [ --enable-purify-safety purify-safe mode], if test "$enable_purify_safety" = "yes"; then diff --git a/include/ffi.h.in b/include/ffi.h.in index 38885b0..14ec807 100644 --- a/include/ffi.h.in +++ b/include/ffi.h.in @@ -310,7 +310,10 @@ typedef struct { void *trampoline_table; void *trampoline_table_entry; #else - char tramp[FFI_TRAMPOLINE_SIZE]; + union { + char tramp[FFI_TRAMPOLINE_SIZE]; + void *ftramp; + }; #endif ffi_cif *cif; void (*fun)(ffi_cif*,void*,void**,void*); diff --git a/include/ffi_common.h b/include/ffi_common.h index 76b9dd6..d3db33a 100644 --- a/include/ffi_common.h +++ b/include/ffi_common.h @@ -103,6 +103,10 @@ ffi_status ffi_prep_cif_core(ffi_cif *cif, some targets. */ void *ffi_data_to_code_pointer (void *data) FFI_HIDDEN; +/* The arch code calls this to determine if a given closure has a + static trampoline. */ +int ffi_tramp_is_present (void *closure); + /* Extended cif, used in callback from assembly routine */ typedef struct { diff --git a/include/tramp.h b/include/tramp.h new file mode 100644 index 0000000..cc096a4 --- /dev/null +++ b/include/tramp.h @@ -0,0 +1,24 @@ +/* ----------------------------------------------------------------------- + ffi_tramp.h - Copyright (C) 2021 Microsoft, Inc. + + Static trampoline definitions. + ----------------------------------------------------------------------- */ + +#ifndef FFI_TRAMP_H +#define FFI_TRAMP_H + +#ifdef __cplusplus +extern "C" { +#endif + +int ffi_tramp_is_supported(void); +void *ffi_tramp_alloc (int flags); +void ffi_tramp_set_parms (void *tramp, void *data, void *code); +void *ffi_tramp_get_addr (void *tramp); +void ffi_tramp_free (void *tramp); + +#ifdef __cplusplus +} +#endif + +#endif /* FFI_TRAMP_H */ diff --git a/src/aarch64/ffi.c b/src/aarch64/ffi.c index ef09f4d..8e24a96 100644 --- a/src/aarch64/ffi.c +++ b/src/aarch64/ffi.c @@ -30,6 +30,7 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #ifdef _WIN32 #include /* FlushInstructionCache */ #endif +#include /* Force FFI_TYPE_LONGDOUBLE to be different than FFI_TYPE_DOUBLE; all further uses in this file will refer to the 128-bit type. */ @@ -782,6 +783,10 @@ ffi_call_go (ffi_cif *cif, void (*fn) (void), void *rvalue, extern void ffi_closure_SYSV (void) FFI_HIDDEN; extern void ffi_closure_SYSV_V (void) FFI_HIDDEN; +#if defined(FFI_EXEC_STATIC_TRAMP) +extern void ffi_closure_SYSV_alt (void) FFI_HIDDEN; +extern void ffi_closure_SYSV_V_alt (void) FFI_HIDDEN; +#endif ffi_status ffi_prep_closure_loc (ffi_closure *closure, @@ -816,7 +821,21 @@ ffi_prep_closure_loc (ffi_closure *closure, 0x00, 0x02, 0x1f, 0xd6 /* br x16 */ }; char *tramp = closure->tramp; - + +#if defined(FFI_EXEC_STATIC_TRAMP) + if (ffi_tramp_is_present(closure)) + { + /* Initialize the static trampoline's parameters. */ + if (start == ffi_closure_SYSV_V) + start = ffi_closure_SYSV_V_alt; + else + start = ffi_closure_SYSV_alt; + ffi_tramp_set_parms (closure->ftramp, start, closure); + goto out; + } +#endif + + /* Initialize the dynamic trampoline. */ memcpy (tramp, trampoline, sizeof(trampoline)); *(UINT64 *)(tramp + 16) = (uintptr_t)start; @@ -832,6 +851,7 @@ ffi_prep_closure_loc (ffi_closure *closure, unsigned char *tramp_code = ffi_data_to_code_pointer (tramp); #endif ffi_clear_cache (tramp_code, tramp_code + FFI_TRAMPOLINE_SIZE); +out: #endif closure->cif = cif; @@ -1022,4 +1042,16 @@ ffi_closure_SYSV_inner (ffi_cif *cif, return flags; } +#if defined(FFI_EXEC_STATIC_TRAMP) +void * +ffi_tramp_arch (size_t *tramp_size, size_t *map_size) +{ + extern void *trampoline_code_table; + + *tramp_size = AARCH64_TRAMP_SIZE; + *map_size = AARCH64_TRAMP_MAP_SIZE; + return &trampoline_code_table; +} +#endif + #endif /* (__aarch64__) || defined(__arm64__)|| defined (_M_ARM64)*/ diff --git a/src/aarch64/internal.h b/src/aarch64/internal.h index 3d4d035..de55755 100644 --- a/src/aarch64/internal.h +++ b/src/aarch64/internal.h @@ -66,3 +66,13 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #define N_X_ARG_REG 8 #define N_V_ARG_REG 8 #define CALL_CONTEXT_SIZE (N_V_ARG_REG * 16 + N_X_ARG_REG * 8) + +#if defined(FFI_EXEC_STATIC_TRAMP) +/* + * For the trampoline code table mapping, a mapping size of 16K is chosen to + * cover the base page sizes of 4K and 16K. + */ +#define AARCH64_TRAMP_MAP_SHIFT 14 +#define AARCH64_TRAMP_MAP_SIZE (1 << AARCH64_TRAMP_MAP_SHIFT) +#define AARCH64_TRAMP_SIZE 32 +#endif diff --git a/src/aarch64/sysv.S b/src/aarch64/sysv.S index b720a92..a3c1508 100644 --- a/src/aarch64/sysv.S +++ b/src/aarch64/sysv.S @@ -367,6 +367,76 @@ CNAME(ffi_closure_SYSV): .size CNAME(ffi_closure_SYSV), . - CNAME(ffi_closure_SYSV) #endif +#if defined(FFI_EXEC_STATIC_TRAMP) + .align 4 +CNAME(ffi_closure_SYSV_V_alt): + /* See the comments above trampoline_code_table. */ + ldr x17, [sp, #8] /* Load closure in x17 */ + add sp, sp, #16 /* Restore the stack */ + b CNAME(ffi_closure_SYSV_V) + + .globl CNAME(ffi_closure_SYSV_V_alt) + FFI_HIDDEN(CNAME(ffi_closure_SYSV_V_alt)) +#ifdef __ELF__ + .type CNAME(ffi_closure_SYSV_V_alt), #function + .size CNAME(ffi_closure_SYSV_V_alt), . - CNAME(ffi_closure_SYSV_V_alt) +#endif + + .align 4 +CNAME(ffi_closure_SYSV_alt): + /* See the comments above trampoline_code_table. */ + ldr x17, [sp, #8] /* Load closure in x17 */ + add sp, sp, #16 /* Restore the stack */ + b CNAME(ffi_closure_SYSV) + + .globl CNAME(ffi_closure_SYSV_alt) + FFI_HIDDEN(CNAME(ffi_closure_SYSV_alt)) +#ifdef __ELF__ + .type CNAME(ffi_closure_SYSV_alt), #function + .size CNAME(ffi_closure_SYSV_alt), . - CNAME(ffi_closure_SYSV_alt) +#endif + +/* + * Below is the definition of the trampoline code table. Each element in + * the code table is a trampoline. + */ +/* + * The trampoline uses register x17. It saves the original value of x17 on + * the stack. + * + * The trampoline has two parameters - target code to jump to and data for + * the target code. The trampoline extracts the parameters from its parameter + * block (see tramp_table_map()). The trampoline saves the data address on + * the stack. Finally, it jumps to the target code. + * + * The target code can choose to: + * + * - restore the value of x17 + * - load the data address in a register + * - restore the stack pointer to what it was when the trampoline was invoked. + */ + .align AARCH64_TRAMP_MAP_SHIFT +CNAME(trampoline_code_table): + .rept AARCH64_TRAMP_MAP_SIZE / AARCH64_TRAMP_SIZE + sub sp, sp, #16 /* Make space on the stack */ + str x17, [sp] /* Save x17 on stack */ + adr x17, #16376 /* Get data address */ + ldr x17, [x17] /* Copy data into x17 */ + str x17, [sp, #8] /* Save data on stack */ + adr x17, #16372 /* Get code address */ + ldr x17, [x17] /* Load code address into x17 */ + br x17 /* Jump to code */ + .endr + + .globl CNAME(trampoline_code_table) + FFI_HIDDEN(CNAME(trampoline_code_table)) +#ifdef __ELF__ + .type CNAME(trampoline_code_table), #function + .size CNAME(trampoline_code_table), . - CNAME(trampoline_code_table) +#endif + .align AARCH64_TRAMP_MAP_SHIFT +#endif /* FFI_EXEC_STATIC_TRAMP */ + #if FFI_EXEC_TRAMPOLINE_TABLE #ifdef __MACH__ diff --git a/src/arm/ffi.c b/src/arm/ffi.c index 0058390..5ad59ce 100644 --- a/src/arm/ffi.c +++ b/src/arm/ffi.c @@ -34,6 +34,7 @@ #include #include #include +#include #include "internal.h" #if defined(_MSC_VER) && defined(_M_ARM) @@ -571,6 +572,10 @@ ffi_closure_inner_VFP (ffi_cif *cif, void ffi_closure_SYSV (void) FFI_HIDDEN; void ffi_closure_VFP (void) FFI_HIDDEN; +#if defined(FFI_EXEC_STATIC_TRAMP) +void ffi_closure_SYSV_alt (void) FFI_HIDDEN; +void ffi_closure_VFP_alt (void) FFI_HIDDEN; +#endif #ifdef FFI_GO_CLOSURES void ffi_go_closure_SYSV (void) FFI_HIDDEN; @@ -612,6 +617,20 @@ ffi_prep_closure_loc (ffi_closure * closure, config[1] = closure_func; #else +#if defined(FFI_EXEC_STATIC_TRAMP) + if (ffi_tramp_is_present(closure)) + { + /* Initialize the static trampoline's parameters. */ + if (closure_func == ffi_closure_SYSV) + closure_func = ffi_closure_SYSV_alt; + else + closure_func = ffi_closure_VFP_alt; + ffi_tramp_set_parms (closure->ftramp, closure_func, closure); + goto out; + } +#endif + + /* Initialize the dynamic trampoline. */ #ifndef _M_ARM memcpy(closure->tramp, ffi_arm_trampoline, 8); #else @@ -633,6 +652,7 @@ ffi_prep_closure_loc (ffi_closure * closure, #else *(void (**)(void))(closure->tramp + 8) = closure_func; #endif +out: #endif closure->cif = cif; @@ -873,4 +893,16 @@ layout_vfp_args (ffi_cif * cif) } } +#if defined(FFI_EXEC_STATIC_TRAMP) +void * +ffi_tramp_arch (size_t *tramp_size, size_t *map_size) +{ + extern void *trampoline_code_table; + + *tramp_size = ARM_TRAMP_SIZE; + *map_size = ARM_TRAMP_MAP_SIZE; + return &trampoline_code_table; +} +#endif + #endif /* __arm__ or _M_ARM */ diff --git a/src/arm/internal.h b/src/arm/internal.h index 6cf0b2a..fa8ab0b 100644 --- a/src/arm/internal.h +++ b/src/arm/internal.h @@ -5,3 +5,13 @@ #define ARM_TYPE_INT 4 #define ARM_TYPE_VOID 5 #define ARM_TYPE_STRUCT 6 + +#if defined(FFI_EXEC_STATIC_TRAMP) +/* + * For the trampoline table mapping, a mapping size of 4K (base page size) + * is chosen. + */ +#define ARM_TRAMP_MAP_SHIFT 12 +#define ARM_TRAMP_MAP_SIZE (1 << ARM_TRAMP_MAP_SHIFT) +#define ARM_TRAMP_SIZE 20 +#endif diff --git a/src/arm/sysv.S b/src/arm/sysv.S index 74bc53f..49c561e 100644 --- a/src/arm/sysv.S +++ b/src/arm/sysv.S @@ -354,6 +354,53 @@ E(ARM_TYPE_STRUCT) cfi_endproc ARM_FUNC_END(ffi_closure_ret) +#if defined(FFI_EXEC_STATIC_TRAMP) +ARM_FUNC_START(ffi_closure_SYSV_alt) + /* See the comments above trampoline_code_table. */ + ldr ip, [sp, #4] /* Load closure in ip */ + add sp, sp, 8 /* Restore the stack */ + b CNAME(ffi_closure_SYSV) +ARM_FUNC_END(ffi_closure_SYSV_alt) + +ARM_FUNC_START(ffi_closure_VFP_alt) + /* See the comments above trampoline_code_table. */ + ldr ip, [sp, #4] /* Load closure in ip */ + add sp, sp, 8 /* Restore the stack */ + b CNAME(ffi_closure_VFP) +ARM_FUNC_END(ffi_closure_VFP_alt) + +/* + * Below is the definition of the trampoline code table. Each element in + * the code table is a trampoline. + */ +/* + * The trampoline uses register ip (r12). It saves the original value of ip + * on the stack. + * + * The trampoline has two parameters - target code to jump to and data for + * the target code. The trampoline extracts the parameters from its parameter + * block (see tramp_table_map()). The trampoline saves the data address on + * the stack. Finally, it jumps to the target code. + * + * The target code can choose to: + * + * - restore the value of ip + * - load the data address in a register + * - restore the stack pointer to what it was when the trampoline was invoked. + */ + .align ARM_TRAMP_MAP_SHIFT +ARM_FUNC_START(trampoline_code_table) + .rept ARM_TRAMP_MAP_SIZE / ARM_TRAMP_SIZE + sub sp, sp, #8 /* Make space on the stack */ + str ip, [sp] /* Save ip on stack */ + ldr ip, [pc, #4080] /* Copy data into ip */ + str ip, [sp, #4] /* Save data on stack */ + ldr pc, [pc, #4076] /* Copy code into PC */ + .endr +ARM_FUNC_END(trampoline_code_table) + .align ARM_TRAMP_MAP_SHIFT +#endif /* FFI_EXEC_STATIC_TRAMP */ + #if FFI_EXEC_TRAMPOLINE_TABLE #ifdef __MACH__ diff --git a/src/closures.c b/src/closures.c index dfc2f68..3a63c32 100644 --- a/src/closures.c +++ b/src/closures.c @@ -34,6 +34,7 @@ #include #include #include +#include #ifdef __NetBSD__ #include @@ -112,6 +113,12 @@ ffi_closure_free (void *ptr) munmap(dataseg, rounded_size); munmap(codeseg, rounded_size); } + +int +ffi_tramp_is_present (__attribute__((unused)) void *ptr) +{ + return 0; +} #else /* !NetBSD with PROT_MPROTECT */ #if !FFI_MMAP_EXEC_WRIT && !FFI_EXEC_TRAMPOLINE_TABLE @@ -860,6 +867,12 @@ dlmmap (void *start, size_t length, int prot, && flags == (MAP_PRIVATE | MAP_ANONYMOUS) && fd == -1 && offset == 0); + if (execfd == -1 && ffi_tramp_is_supported ()) + { + ptr = mmap (start, length, prot & ~PROT_EXEC, flags, fd, offset); + return ptr; + } + if (execfd == -1 && is_emutramp_enabled ()) { ptr = mmap (start, length, prot & ~PROT_EXEC, flags, fd, offset); @@ -939,7 +952,7 @@ segment_holding_code (mstate m, char* addr) void * ffi_closure_alloc (size_t size, void **code) { - void *ptr; + void *ptr, *ftramp; if (!code) return NULL; @@ -951,6 +964,17 @@ ffi_closure_alloc (size_t size, void **code) msegmentptr seg = segment_holding (gm, ptr); *code = add_segment_exec_offset (ptr, seg); + if (!ffi_tramp_is_supported ()) + return ptr; + + ftramp = ffi_tramp_alloc (0); + if (ftramp == NULL) + { + dlfree (FFI_RESTORE_PTR (ptr)); + return NULL; + } + *code = ffi_tramp_get_addr (ftramp); + ((ffi_closure *) ptr)->ftramp = ftramp; } return ptr; @@ -965,7 +989,11 @@ ffi_data_to_code_pointer (void *data) burden of managing this memory themselves, in which case this we'll just return data. */ if (seg) - return add_segment_exec_offset (data, seg); + { + if (!ffi_tramp_is_supported ()) + return add_segment_exec_offset (data, seg); + return ffi_tramp_get_addr (((ffi_closure *) data)->ftramp); + } else return data; } @@ -983,10 +1011,19 @@ ffi_closure_free (void *ptr) if (seg) ptr = sub_segment_exec_offset (ptr, seg); #endif + if (ffi_tramp_is_supported ()) + ffi_tramp_free (((ffi_closure *) ptr)->ftramp); dlfree (FFI_RESTORE_PTR (ptr)); } +int +ffi_tramp_is_present (void *ptr) +{ + msegmentptr seg = segment_holding (gm, ptr); + return seg != NULL && ffi_tramp_is_supported(); +} + # else /* ! FFI_MMAP_EXEC_WRIT */ /* On many systems, memory returned by malloc is writable and @@ -1015,6 +1052,12 @@ ffi_data_to_code_pointer (void *data) return data; } +int +ffi_tramp_is_present (__attribute__((unused)) void *ptr) +{ + return 0; +} + # endif /* ! FFI_MMAP_EXEC_WRIT */ #endif /* FFI_CLOSURES */ diff --git a/src/tramp.c b/src/tramp.c new file mode 100644 index 0000000..265aeaa --- /dev/null +++ b/src/tramp.c @@ -0,0 +1,729 @@ +/* ----------------------------------------------------------------------- + tramp.c - Copyright (c) 2020 Madhavan T. Venkataraman + + API and support functions for managing statically defined closure + trampolines. + + Permission is hereby granted, free of charge, to any person obtaining + a copy of this software and associated documentation files (the + ``Software''), to deal in the Software without restriction, including + without limitation the rights to use, copy, modify, merge, publish, + distribute, sublicense, and/or sell copies of the Software, and to + permit persons to whom the Software is furnished to do so, subject to + the following conditions: + + The above copyright notice and this permission notice shall be included + in all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, + EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, + WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + DEALINGS IN THE SOFTWARE. + ----------------------------------------------------------------------- */ + +#include + +#ifdef FFI_EXEC_STATIC_TRAMP + +/* -------------------------- Headers and Definitions ---------------------*/ +/* + * Add support for other OSes later. For now, it is just Linux. + */ + +#if defined __linux__ +#ifdef __linux__ +#define _GNU_SOURCE 1 +#endif +#include +#include +#include +#include +#include +#include +#include +#include +#ifdef __linux__ +#include +#include +#endif +#endif /* __linux__ */ + +/* + * Each architecture defines static code for a trampoline code table. The + * trampoline code table is mapped into the address space of a process. + * + * The following architecture specific function returns: + * + * - the address of the trampoline code table in the text segment + * - the size of each trampoline in the trampoline code table + * - the size of the mapping for the whole trampoline code table + */ +void __attribute__((weak)) *ffi_tramp_arch (size_t *tramp_size, + size_t *map_size); + +/* ------------------------- Trampoline Data Structures --------------------*/ + +struct tramp; + +/* + * Trampoline table. Manages one trampoline code table and one trampoline + * parameter table. + * + * prev, next Links in the global trampoline table list. + * code_table Trampoline code table mapping. + * parm_table Trampoline parameter table mapping. + * array Array of trampolines malloced. + * free List of free trampolines. + * nfree Number of free trampolines. + */ +struct tramp_table +{ + struct tramp_table *prev; + struct tramp_table *next; + void *code_table; + void *parm_table; + struct tramp *array; + struct tramp *free; + int nfree; +}; + +/* + * Parameters for each trampoline. + * + * data + * Data for the target code that the trampoline jumps to. + * target + * Target code that the trampoline jumps to. + */ +struct tramp_parm +{ + void *data; + void *target; +}; + +/* + * Trampoline structure for each trampoline. + * + * prev, next Links in the trampoline free list of a trampoline table. + * table Trampoline table to which this trampoline belongs. + * code Address of this trampoline in the code table mapping. + * parm Address of this trampoline's parameters in the parameter + * table mapping. + */ +struct tramp +{ + struct tramp *prev; + struct tramp *next; + struct tramp_table *table; + void *code; + struct tramp_parm *parm; +}; + +enum tramp_globals_status { + TRAMP_GLOBALS_UNINITIALIZED = 0, + TRAMP_GLOBALS_PASSED, + TRAMP_GLOBALS_FAILED, +}; + +/* + * Trampoline globals. + * + * fd + * File descriptor of binary file that contains the trampoline code table. + * offset + * Offset of the trampoline code table in that file. + * text + * Address of the trampoline code table in the text segment. + * map_size + * Size of the trampoline code table mapping. + * size + * Size of one trampoline in the trampoline code table. + * ntramp + * Total number of trampolines in the trampoline code table. + * free_tables + * List of trampoline tables that contain free trampolines. + * nfree_tables + * Number of trampoline tables that contain free trampolines. + * status + * Initialization status. + */ +struct tramp_globals +{ + int fd; + off_t offset; + void *text; + size_t map_size; + size_t size; + int ntramp; + struct tramp_table *free_tables; + int nfree_tables; + enum tramp_globals_status status; +}; + +static struct tramp_globals tramp_globals; + +/* --------------------- Trampoline File Initialization --------------------*/ + +/* + * The trampoline file is the file used to map the trampoline code table into + * the address space of a process. There are two ways to get this file: + * + * - From the OS. E.g., on Linux, /proc//maps lists all the memory + * mappings for . For file-backed mappings, maps supplies the file name + * and the file offset. Using this, we can locate the mapping that maps + * libffi and get the path to the libffi binary. And, we can compute the + * offset of the trampoline code table within that binary. + * + * - Else, if we can create a temporary file, we can write the trampoline code + * table from the text segment into the temporary file. + * + * The first method is the preferred one. If the OS security subsystem + * disallows mapping unsigned files with PROT_EXEC, then the second method + * will fail. + * + * If an OS allows the trampoline code table in the text segment to be + * directly remapped (e.g., MACH vm_remap ()), then we don't need the + * trampoline file. + */ +static int tramp_table_alloc (void); + +#if defined __linux__ + +static int +ffi_tramp_get_libffi (void) +{ + FILE *fp; + char file[PATH_MAX], line[PATH_MAX+100], perm[10], dev[10]; + unsigned long start, end, offset, inode; + uintptr_t addr = (uintptr_t) tramp_globals.text; + int nfields, found; + + snprintf (file, PATH_MAX, "/proc/%d/maps", getpid()); + fp = fopen (file, "r"); + if (fp == NULL) + return 0; + + found = 0; + while (feof (fp) == 0) { + if (fgets (line, sizeof (line), fp) == 0) + break; + + nfields = sscanf (line, "%lx-%lx %9s %lx %9s %ld %s", + &start, &end, perm, &offset, dev, &inode, file); + if (nfields != 7) + continue; + + if (addr >= start && addr < end) { + tramp_globals.offset = offset + (addr - start); + found = 1; + break; + } + } + fclose (fp); + + if (!found) + return 0; + + tramp_globals.fd = open (file, O_RDONLY); + if (tramp_globals.fd == -1) + return 0; + + /* + * Allocate a trampoline table just to make sure that the trampoline code + * table can be mapped. + */ + if (!tramp_table_alloc ()) + { + close (tramp_globals.fd); + tramp_globals.fd = -1; + return 0; + } + return 1; +} + +#endif /* __linux__ */ + +#if defined __linux__ + +#if defined HAVE_MKSTEMP + +static int +ffi_tramp_get_temp_file (void) +{ + char template[12] = "/tmp/XXXXXX"; + ssize_t count; + + tramp_globals.offset = 0; + tramp_globals.fd = mkstemp (template); + if (tramp_globals.fd == -1) + return 0; + + unlink (template); + /* + * Write the trampoline code table into the temporary file and allocate a + * trampoline table to make sure that the temporary file can be mapped. + */ + count = write(tramp_globals.fd, tramp_globals.text, tramp_globals.map_size); + if (count == tramp_globals.map_size && tramp_table_alloc ()) + return 1; + + close (tramp_globals.fd); + tramp_globals.fd = -1; + return 0; +} + +#else /* !defined HAVE_MKSTEMP */ + +/* + * TODO: + * src/closures.c contains code for finding temp file that has EXEC + * permissions. May be, some of that code can be shared with static + * trampolines. + */ +static int +ffi_tramp_get_temp_file (void) +{ + tramp_globals.offset = 0; + tramp_globals.fd = -1; + return 0; +} + +#endif /* defined HAVE_MKSTEMP */ + +#endif /* __linux__ */ + +/* ------------------------ OS-specific Initialization ----------------------*/ + +#if defined __linux__ + +static int +ffi_tramp_init_os (void) +{ + if (ffi_tramp_get_libffi ()) + return 1; + return ffi_tramp_get_temp_file (); +} + +#endif /* __linux__ */ + +/* --------------------------- OS-specific Locking -------------------------*/ + +#if defined __linux__ + +static pthread_mutex_t tramp_globals_mutex = PTHREAD_MUTEX_INITIALIZER; + +static void +ffi_tramp_lock(void) +{ + pthread_mutex_lock (&tramp_globals_mutex); +} + +static void +ffi_tramp_unlock() +{ + pthread_mutex_unlock (&tramp_globals_mutex); +} + +#endif /* __linux__ */ + +/* ------------------------ OS-specific Memory Mapping ----------------------*/ + +/* + * Create a trampoline code table mapping and a trampoline parameter table + * mapping. The two mappings must be adjacent to each other for PC-relative + * access. + * + * For each trampoline in the code table, there is a corresponding parameter + * block in the parameter table. The size of the parameter block is the same + * as the size of the trampoline. This means that the parameter block is at + * a fixed offset from its trampoline making it easy for a trampoline to find + * its parameters using PC-relative access. + * + * The parameter block will contain a struct tramp_parm. This means that + * sizeof (struct tramp_parm) cannot exceed the size of a parameter block. + */ + +#if defined __linux__ + +static int +tramp_table_map (struct tramp_table *table) +{ + char *addr; + + /* + * Create an anonymous mapping twice the map size. The top half will be used + * for the code table. The bottom half will be used for the parameter table. + */ + addr = mmap (NULL, tramp_globals.map_size * 2, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (addr == MAP_FAILED) + return 0; + + /* + * Replace the top half of the anonymous mapping with the code table mapping. + */ + table->code_table = mmap (addr, tramp_globals.map_size, PROT_READ | PROT_EXEC, + MAP_PRIVATE | MAP_FIXED, tramp_globals.fd, tramp_globals.offset); + if (table->code_table == MAP_FAILED) + { + (void) munmap (addr, tramp_globals.map_size * 2); + return 0; + } + table->parm_table = table->code_table + tramp_globals.map_size; + return 1; +} + +static void +tramp_table_unmap (struct tramp_table *table) +{ + (void) munmap (table->code_table, tramp_globals.map_size); + (void) munmap (table->parm_table, tramp_globals.map_size); +} + +#endif /* __linux__ */ + +/* ------------------------ Trampoline Initialization ----------------------*/ + +/* + * Initialize the static trampoline feature. + */ +static int +ffi_tramp_init (void) +{ + if (tramp_globals.status == TRAMP_GLOBALS_PASSED) + return 1; + + if (tramp_globals.status == TRAMP_GLOBALS_FAILED) + return 0; + + if (ffi_tramp_arch == NULL) + { + tramp_globals.status = TRAMP_GLOBALS_FAILED; + return 0; + } + + tramp_globals.free_tables = NULL; + tramp_globals.nfree_tables = 0; + + /* + * Get trampoline code table information from the architecture. + */ + tramp_globals.text = ffi_tramp_arch (&tramp_globals.size, + &tramp_globals.map_size); + tramp_globals.ntramp = tramp_globals.map_size / tramp_globals.size; + + if (sysconf (_SC_PAGESIZE) > tramp_globals.map_size) + return 0; + + if (ffi_tramp_init_os ()) + { + tramp_globals.status = TRAMP_GLOBALS_PASSED; + return 1; + } + + tramp_globals.status = TRAMP_GLOBALS_FAILED; + return 0; +} + +/* ---------------------- Trampoline Table functions ---------------------- */ + +/* This code assumes that malloc () is available on all OSes. */ + +static void tramp_add (struct tramp *tramp); + +/* + * Allocate and initialize a trampoline table. + */ +static int +tramp_table_alloc (void) +{ + struct tramp_table *table; + struct tramp *tramp_array, *tramp; + size_t size; + char *code, *parm; + int i; + + /* + * If we already have tables with free trampolines, there is no need to + * allocate a new table. + */ + if (tramp_globals.nfree_tables > 0) + return 1; + + /* + * Allocate a new trampoline table structure. + */ + table = malloc (sizeof (*table)); + if (table == NULL) + return 0; + + /* + * Allocate new trampoline structures. + */ + tramp_array = malloc (sizeof (*tramp) * tramp_globals.ntramp); + if (tramp_array == NULL) + goto free_table; + + /* + * Map a code table and a parameter table into the caller's address space. + */ + if (!tramp_table_map (table)) + { + /* + * Failed to map the code and parameter tables. + */ + goto free_tramp_array; + } + + /* + * Initialize the trampoline table. + */ + table->array = tramp_array; + table->free = NULL; + table->nfree = 0; + + /* + * Populate the trampoline table free list. This will also add the trampoline + * table to the global list of trampoline tables. + */ + size = tramp_globals.size; + code = table->code_table; + parm = table->parm_table; + for (i = 0; i < tramp_globals.ntramp; i++) + { + tramp = &tramp_array[i]; + tramp->table = table; + tramp->code = code; + tramp->parm = (struct tramp_parm *) parm; + tramp_add (tramp); + + code += size; + parm += size; + } + /* Success */ + return 1; + +/* Failure */ +free_tramp_array: + free (tramp_array); +free_table: + free (table); + return 0; +} + +/* + * Free a trampoline table. + */ +static void +tramp_table_free (struct tramp_table *table) +{ + tramp_table_unmap (table); + free (table->array); + free (table); +} + +/* + * Add a new trampoline table to the global table list. + */ +static void +tramp_table_add (struct tramp_table *table) +{ + table->next = tramp_globals.free_tables; + table->prev = NULL; + if (tramp_globals.free_tables != NULL) + tramp_globals.free_tables->prev = table; + tramp_globals.free_tables = table; + tramp_globals.nfree_tables++; +} + +/* + * Delete a trampoline table from the global table list. + */ +static void +tramp_table_del (struct tramp_table *table) +{ + tramp_globals.nfree_tables--; + if (table->prev != NULL) + table->prev->next = table->next; + if (table->next != NULL) + table->next->prev = table->prev; + if (tramp_globals.free_tables == table) + tramp_globals.free_tables = table->next; +} + +/* ------------------------- Trampoline functions ------------------------- */ + +/* + * Add a trampoline to its trampoline table. + */ +static void +tramp_add (struct tramp *tramp) +{ + struct tramp_table *table = tramp->table; + + tramp->next = table->free; + tramp->prev = NULL; + if (table->free != NULL) + table->free->prev = tramp; + table->free = tramp; + table->nfree++; + + if (table->nfree == 1) + tramp_table_add (table); + + /* + * We don't want to keep too many free trampoline tables lying around. + */ + if (table->nfree == tramp_globals.ntramp && + tramp_globals.nfree_tables > 1) + { + tramp_table_del (table); + tramp_table_free (table); + } +} + +/* + * Remove a trampoline from its trampoline table. + */ +static void +tramp_del (struct tramp *tramp) +{ + struct tramp_table *table = tramp->table; + + table->nfree--; + if (tramp->prev != NULL) + tramp->prev->next = tramp->next; + if (tramp->next != NULL) + tramp->next->prev = tramp->prev; + if (table->free == tramp) + table->free = tramp->next; + + if (table->nfree == 0) + tramp_table_del (table); +} + +/* ------------------------ Trampoline API functions ------------------------ */ + +int +ffi_tramp_is_supported(void) +{ + int ret; + + ffi_tramp_lock(); + ret = ffi_tramp_init (); + ffi_tramp_unlock(); + return ret; +} + +/* + * Allocate a trampoline and return its opaque address. + */ +void * +ffi_tramp_alloc (int flags) +{ + struct tramp *tramp; + + ffi_tramp_lock(); + + if (!ffi_tramp_init () || flags != 0) + { + ffi_tramp_unlock(); + return NULL; + } + + if (!tramp_table_alloc ()) + { + ffi_tramp_unlock(); + return NULL; + } + + tramp = tramp_globals.free_tables->free; + tramp_del (tramp); + + ffi_tramp_unlock(); + + return tramp; +} + +/* + * Set the parameters for a trampoline. + */ +void +ffi_tramp_set_parms (void *arg, void *target, void *data) +{ + struct tramp *tramp = arg; + + ffi_tramp_lock(); + tramp->parm->target = target; + tramp->parm->data = data; + ffi_tramp_unlock(); +} + +/* + * Get the invocation address of a trampoline. + */ +void * +ffi_tramp_get_addr (void *arg) +{ + struct tramp *tramp = arg; + void *addr; + + ffi_tramp_lock(); + addr = tramp->code; + ffi_tramp_unlock(); + + return addr; +} + +/* + * Free a trampoline. + */ +void +ffi_tramp_free (void *arg) +{ + struct tramp *tramp = arg; + + ffi_tramp_lock(); + tramp_add (tramp); + ffi_tramp_unlock(); +} + +/* ------------------------------------------------------------------------- */ + +#else /* !FFI_EXEC_STATIC_TRAMP */ + +#include + +int +ffi_tramp_is_supported(void) +{ + return 0; +} + +void * +ffi_tramp_alloc (int flags) +{ + return NULL; +} + +void +ffi_tramp_set_parms (void *arg, void *target, void *data) +{ +} + +void * +ffi_tramp_get_addr (void *arg) +{ + return NULL; +} + +void +ffi_tramp_free (void *arg) +{ +} + +#endif /* FFI_EXEC_STATIC_TRAMP */ diff --git a/src/x86/ffi.c b/src/x86/ffi.c index 5f7fd81..b4d0d39 100644 --- a/src/x86/ffi.c +++ b/src/x86/ffi.c @@ -34,6 +34,7 @@ #include #include #include +#include #include "internal.h" /* Force FFI_TYPE_LONGDOUBLE to be different than FFI_TYPE_DOUBLE; @@ -411,6 +412,11 @@ ffi_call_go (ffi_cif *cif, void (*fn)(void), void *rvalue, void FFI_HIDDEN ffi_closure_i386(void); void FFI_HIDDEN ffi_closure_STDCALL(void); void FFI_HIDDEN ffi_closure_REGISTER(void); +#if defined(FFI_EXEC_STATIC_TRAMP) +void FFI_HIDDEN ffi_closure_i386_alt(void); +void FFI_HIDDEN ffi_closure_STDCALL_alt(void); +void FFI_HIDDEN ffi_closure_REGISTER_alt(void); +#endif struct closure_frame { @@ -559,6 +565,22 @@ ffi_prep_closure_loc (ffi_closure* closure, return FFI_BAD_ABI; } +#if defined(FFI_EXEC_STATIC_TRAMP) + if (ffi_tramp_is_present(closure)) + { + /* Initialize the static trampoline's parameters. */ + if (dest == ffi_closure_i386) + dest = ffi_closure_i386_alt; + else if (dest == ffi_closure_STDCALL) + dest = ffi_closure_STDCALL_alt; + else + dest = ffi_closure_REGISTER_alt; + ffi_tramp_set_parms (closure->ftramp, dest, closure); + goto out; + } +#endif + + /* Initialize the dynamic trampoline. */ /* endbr32. */ *(UINT32 *) tramp = 0xfb1e0ff3; @@ -570,6 +592,7 @@ ffi_prep_closure_loc (ffi_closure* closure, tramp[9] = 0xe9; *(unsigned *)(tramp + 10) = (unsigned)dest - ((unsigned)codeloc + 14); +out: closure->cif = cif; closure->fun = fun; closure->user_data = user_data; @@ -767,4 +790,17 @@ ffi_raw_call(ffi_cif *cif, void (*fn)(void), void *rvalue, ffi_raw *avalue) ffi_call_i386 (frame, stack); } #endif /* !FFI_NO_RAW_API */ + +#if defined(FFI_EXEC_STATIC_TRAMP) +void * +ffi_tramp_arch (size_t *tramp_size, size_t *map_size) +{ + extern void *trampoline_code_table; + + *map_size = X86_TRAMP_MAP_SIZE; + *tramp_size = X86_TRAMP_SIZE; + return &trampoline_code_table; +} +#endif + #endif /* __i386__ */ diff --git a/src/x86/ffi64.c b/src/x86/ffi64.c index 39f9598..5264cdf 100644 --- a/src/x86/ffi64.c +++ b/src/x86/ffi64.c @@ -33,6 +33,7 @@ #include #include #include +#include #include "internal64.h" #ifdef __x86_64__ @@ -714,6 +715,10 @@ ffi_call_go (ffi_cif *cif, void (*fn)(void), void *rvalue, extern void ffi_closure_unix64(void) FFI_HIDDEN; extern void ffi_closure_unix64_sse(void) FFI_HIDDEN; +#if defined(FFI_EXEC_STATIC_TRAMP) +extern void ffi_closure_unix64_alt(void) FFI_HIDDEN; +extern void ffi_closure_unix64_sse_alt(void) FFI_HIDDEN; +#endif #ifndef __ILP32__ extern ffi_status @@ -756,9 +761,24 @@ ffi_prep_closure_loc (ffi_closure* closure, else dest = ffi_closure_unix64; +#if defined(FFI_EXEC_STATIC_TRAMP) + if (ffi_tramp_is_present(closure)) + { + /* Initialize the static trampoline's parameters. */ + if (dest == ffi_closure_unix64_sse) + dest = ffi_closure_unix64_sse_alt; + else + dest = ffi_closure_unix64_alt; + ffi_tramp_set_parms (closure->ftramp, dest, closure); + goto out; + } +#endif + + /* Initialize the dynamic trampoline. */ memcpy (tramp, trampoline, sizeof(trampoline)); *(UINT64 *)(tramp + sizeof (trampoline)) = (uintptr_t)dest; +out: closure->cif = cif; closure->fun = fun; closure->user_data = user_data; @@ -892,4 +912,16 @@ ffi_prep_go_closure (ffi_go_closure* closure, ffi_cif* cif, #endif /* FFI_GO_CLOSURES */ +#if defined(FFI_EXEC_STATIC_TRAMP) +void * +ffi_tramp_arch (size_t *tramp_size, size_t *map_size) +{ + extern void *trampoline_code_table; + + *map_size = UNIX64_TRAMP_MAP_SIZE; + *tramp_size = UNIX64_TRAMP_SIZE; + return &trampoline_code_table; +} +#endif + #endif /* __x86_64__ */ diff --git a/src/x86/ffitarget.h b/src/x86/ffitarget.h index a34f3e5..f454341 100644 --- a/src/x86/ffitarget.h +++ b/src/x86/ffitarget.h @@ -147,9 +147,11 @@ typedef enum ffi_abi { # define FFI_NATIVE_RAW_API 1 /* x86 has native raw api support */ #endif -#if !defined(GENERATE_LIBFFI_MAP) && defined(__ASSEMBLER__) \ - && defined(__CET__) +#if !defined(GENERATE_LIBFFI_MAP) && defined(__CET__) # include +# if (__CET__ & 1) != 0 +# define ENDBR_PRESENT +# endif # define _CET_NOTRACK notrack #else # define _CET_ENDBR diff --git a/src/x86/ffiw64.c b/src/x86/ffiw64.c index a43a9eb..6c28d59 100644 --- a/src/x86/ffiw64.c +++ b/src/x86/ffiw64.c @@ -30,6 +30,7 @@ #include #include #include +#include #ifdef X86_WIN64 #define EFI64(name) name @@ -187,6 +188,9 @@ EFI64(ffi_call_go)(ffi_cif *cif, void (*fn)(void), void *rvalue, extern void ffi_closure_win64(void) FFI_HIDDEN; +#if defined(FFI_EXEC_STATIC_TRAMP) +extern void ffi_closure_win64_alt(void) FFI_HIDDEN; +#endif #ifdef FFI_GO_CLOSURES extern void ffi_go_closure_win64(void) FFI_HIDDEN; @@ -220,9 +224,20 @@ EFI64(ffi_prep_closure_loc)(ffi_closure* closure, return FFI_BAD_ABI; } +#if defined(FFI_EXEC_STATIC_TRAMP) + if (ffi_tramp_is_present(closure)) + { + /* Initialize the static trampoline's parameters. */ + ffi_tramp_set_parms (closure->ftramp, ffi_closure_win64_alt, closure); + goto out; + } +#endif + + /* Initialize the dynamic trampoline. */ memcpy (tramp, trampoline, sizeof(trampoline)); *(UINT64 *)(tramp + sizeof (trampoline)) = (uintptr_t)ffi_closure_win64; +out: closure->cif = cif; closure->fun = fun; closure->user_data = user_data; diff --git a/src/x86/internal.h b/src/x86/internal.h index 09771ba..23be7a2 100644 --- a/src/x86/internal.h +++ b/src/x86/internal.h @@ -27,3 +27,17 @@ #else # define HAVE_FASTCALL 1 #endif + +#if defined(FFI_EXEC_STATIC_TRAMP) +/* + * For the trampoline code table mapping, a mapping size of 4K (base page size) + * is chosen. + */ +#define X86_TRAMP_MAP_SHIFT 12 +#define X86_TRAMP_MAP_SIZE (1 << X86_TRAMP_MAP_SHIFT) +#ifdef ENDBR_PRESENT +#define X86_TRAMP_SIZE 44 +#else +#define X86_TRAMP_SIZE 40 +#endif +#endif diff --git a/src/x86/internal64.h b/src/x86/internal64.h index 512e955..282b408 100644 --- a/src/x86/internal64.h +++ b/src/x86/internal64.h @@ -20,3 +20,17 @@ #define UNIX64_FLAG_RET_IN_MEM (1 << 10) #define UNIX64_FLAG_XMM_ARGS (1 << 11) #define UNIX64_SIZE_SHIFT 12 + +#if defined(FFI_EXEC_STATIC_TRAMP) +/* + * For the trampoline code table mapping, a mapping size of 4K (base page size) + * is chosen. + */ +#define UNIX64_TRAMP_MAP_SHIFT 12 +#define UNIX64_TRAMP_MAP_SIZE (1 << UNIX64_TRAMP_MAP_SHIFT) +#ifdef ENDBR_PRESENT +#define UNIX64_TRAMP_SIZE 40 +#else +#define UNIX64_TRAMP_SIZE 32 +#endif +#endif diff --git a/src/x86/sysv.S b/src/x86/sysv.S index d8ab4b0..7110f02 100644 --- a/src/x86/sysv.S +++ b/src/x86/sysv.S @@ -573,6 +573,94 @@ L(UW31): # cfi_endproc ENDF(C(ffi_closure_STDCALL)) +#if defined(FFI_EXEC_STATIC_TRAMP) + .balign 16 + .globl C(ffi_closure_i386_alt) + FFI_HIDDEN(C(ffi_closure_i386_alt)) +C(ffi_closure_i386_alt): + /* See the comments above trampoline_code_table. */ + _CET_ENDBR + movl 4(%esp), %eax /* Load closure in eax */ + add $8, %esp /* Restore the stack */ + jmp C(ffi_closure_i386) +ENDF(C(ffi_closure_i386_alt)) + + .balign 16 + .globl C(ffi_closure_REGISTER_alt) + FFI_HIDDEN(C(ffi_closure_REGISTER_alt)) +C(ffi_closure_REGISTER_alt): + /* See the comments above trampoline_code_table. */ + _CET_ENDBR + movl (%esp), %eax /* Restore eax */ + add $4, %esp /* Leave closure on stack */ + jmp C(ffi_closure_REGISTER) +ENDF(C(ffi_closure_REGISTER_alt)) + + .balign 16 + .globl C(ffi_closure_STDCALL_alt) + FFI_HIDDEN(C(ffi_closure_STDCALL_alt)) +C(ffi_closure_STDCALL_alt): + /* See the comments above trampoline_code_table. */ + _CET_ENDBR + movl 4(%esp), %eax /* Load closure in eax */ + add $8, %esp /* Restore the stack */ + jmp C(ffi_closure_STDCALL) +ENDF(C(ffi_closure_STDCALL_alt)) + +/* + * Below is the definition of the trampoline code table. Each element in + * the code table is a trampoline. + * + * Because we jump to the trampoline, we place a _CET_ENDBR at the + * beginning of the trampoline to mark it as a valid branch target. This is + * part of the the Intel CET (Control Flow Enforcement Technology). + */ +/* + * The trampoline uses register eax. It saves the original value of eax on + * the stack. + * + * The trampoline has two parameters - target code to jump to and data for + * the target code. The trampoline extracts the parameters from its parameter + * block (see tramp_table_map()). The trampoline saves the data address on + * the stack. Finally, it jumps to the target code. + * + * The target code can choose to: + * + * - restore the value of eax + * - load the data address in a register + * - restore the stack pointer to what it was when the trampoline was invoked. + */ +#ifdef ENDBR_PRESENT +#define X86_DATA_OFFSET 4081 +#define X86_CODE_OFFSET 4070 +#else +#define X86_DATA_OFFSET 4085 +#define X86_CODE_OFFSET 4074 +#endif + + .align X86_TRAMP_MAP_SIZE + .globl C(trampoline_code_table) + FFI_HIDDEN(C(trampoline_code_table)) +C(trampoline_code_table): + .rept X86_TRAMP_MAP_SIZE / X86_TRAMP_SIZE + _CET_ENDBR + sub $8, %esp + movl %eax, (%esp) /* Save %eax on stack */ + call 1f /* Get next PC into %eax */ + movl X86_DATA_OFFSET(%eax), %eax /* Copy data into %eax */ + movl %eax, 4(%esp) /* Save data on stack */ + call 1f /* Get next PC into %eax */ + movl X86_CODE_OFFSET(%eax), %eax /* Copy code into %eax */ + jmp *%eax /* Jump to code */ +1: + mov (%esp), %eax + ret + .align 4 + .endr +ENDF(C(trampoline_code_table)) + .align X86_TRAMP_MAP_SIZE +#endif /* FFI_EXEC_STATIC_TRAMP */ + #if !FFI_NO_RAW_API #define raw_closure_S_FS (16+16+12) @@ -1131,6 +1219,7 @@ L(EFDE9): #endif /* __APPLE__ */ #endif /* ifndef _MSC_VER */ + #endif /* ifdef __i386__ */ #if defined __ELF__ && defined __linux__ diff --git a/src/x86/unix64.S b/src/x86/unix64.S index 89d7db1..ca6fe0c 100644 --- a/src/x86/unix64.S +++ b/src/x86/unix64.S @@ -456,6 +456,81 @@ L(sse_entry2): L(UW17): ENDF(C(ffi_go_closure_unix64)) +#if defined(FFI_EXEC_STATIC_TRAMP) + .balign 8 + .globl C(ffi_closure_unix64_sse_alt) + FFI_HIDDEN(C(ffi_closure_unix64_sse_alt)) + +C(ffi_closure_unix64_sse_alt): + /* See the comments above trampoline_code_table. */ + _CET_ENDBR + movq 8(%rsp), %r10 /* Load closure in r10 */ + addq $16, %rsp /* Restore the stack */ + jmp C(ffi_closure_unix64_sse) +ENDF(C(ffi_closure_unix64_sse_alt)) + + .balign 8 + .globl C(ffi_closure_unix64_alt) + FFI_HIDDEN(C(ffi_closure_unix64_alt)) + +C(ffi_closure_unix64_alt): + /* See the comments above trampoline_code_table. */ + _CET_ENDBR + movq 8(%rsp), %r10 /* Load closure in r10 */ + addq $16, %rsp /* Restore the stack */ + jmp C(ffi_closure_unix64) + ENDF(C(ffi_closure_unix64_alt)) + +/* + * Below is the definition of the trampoline code table. Each element in + * the code table is a trampoline. + * + * Because we jump to the trampoline, we place a _CET_ENDBR at the + * beginning of the trampoline to mark it as a valid branch target. This is + * part of the the Intel CET (Control Flow Enforcement Technology). + */ +/* + * The trampoline uses register r10. It saves the original value of r10 on + * the stack. + * + * The trampoline has two parameters - target code to jump to and data for + * the target code. The trampoline extracts the parameters from its parameter + * block (see tramp_table_map()). The trampoline saves the data address on + * the stack. Finally, it jumps to the target code. + * + * The target code can choose to: + * + * - restore the value of r10 + * - load the data address in a register + * - restore the stack pointer to what it was when the trampoline was invoked. + */ +#ifdef ENDBR_PRESENT +#define X86_DATA_OFFSET 4077 +#define X86_CODE_OFFSET 4073 +#else +#define X86_DATA_OFFSET 4081 +#define X86_CODE_OFFSET 4077 +#endif + + .align UNIX64_TRAMP_MAP_SIZE + .globl trampoline_code_table + FFI_HIDDEN(C(trampoline_code_table)) + +C(trampoline_code_table): + .rept UNIX64_TRAMP_MAP_SIZE / UNIX64_TRAMP_SIZE + _CET_ENDBR + subq $16, %rsp /* Make space on the stack */ + movq %r10, (%rsp) /* Save %r10 on stack */ + movq X86_DATA_OFFSET(%rip), %r10 /* Copy data into %r10 */ + movq %r10, 8(%rsp) /* Save data on stack */ + movq X86_CODE_OFFSET(%rip), %r10 /* Copy code into %r10 */ + jmp *%r10 /* Jump to code */ + .align 8 + .endr +ENDF(C(trampoline_code_table)) + .align UNIX64_TRAMP_MAP_SIZE +#endif /* FFI_EXEC_STATIC_TRAMP */ + /* Sadly, OSX cctools-as doesn't understand .cfi directives at all. */ #ifdef __APPLE__ diff --git a/src/x86/win64.S b/src/x86/win64.S index 8315e8b..f3ace8d 100644 --- a/src/x86/win64.S +++ b/src/x86/win64.S @@ -234,6 +234,20 @@ C(ffi_closure_win64): cfi_endproc SEH(.seh_endproc) + +#if defined(FFI_EXEC_STATIC_TRAMP) + .align 8 + .globl C(ffi_closure_win64_alt) + FFI_HIDDEN(C(ffi_closure_win64_alt)) + + SEH(.seh_proc ffi_closure_win64_alt) +C(ffi_closure_win64_alt): + _CET_ENDBR + movq 8(%rsp), %r10 + addq $16, %rsp + jmp C(ffi_closure_win64) + SEH(.seh_endproc) +#endif #endif /* __x86_64__ */ #if defined __ELF__ && defined __linux__ diff --git a/testsuite/libffi.closures/closure_loc_fn0.c b/testsuite/libffi.closures/closure_loc_fn0.c index b3afa0b..ad488ac 100644 --- a/testsuite/libffi.closures/closure_loc_fn0.c +++ b/testsuite/libffi.closures/closure_loc_fn0.c @@ -83,7 +83,10 @@ int main (void) CHECK(ffi_prep_closure_loc(pcl, &cif, closure_loc_test_fn0, (void *) 3 /* userdata */, codeloc) == FFI_OK); +#ifndef FFI_EXEC_STATIC_TRAMP + /* With static trampolines, the codeloc does not point to closure */ CHECK(memcmp(pcl, codeloc, sizeof(*pcl)) == 0); +#endif res = (*((closure_loc_test_type0)codeloc)) (1LL, 2, 3LL, 4, 127, 429LL, 7, 8, 9.5, 10, 11, 12, 13, -- 2.7.4