From 0f842f8a246f2b5b51a11c13f933bf7a90ae8e96 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Tue, 27 Aug 2013 10:22:54 -0700 Subject: [PATCH] exec: Reorganize the GETRA/GETPC macros Always define GETRA; use __builtin_extract_return_addr, rather than having a special case for s390. Split GETPC_ADJ out of GETPC; use 2 universally, rather than having a special case for arm. Rename GETPC_LDST to GETRA_LDST to indicate that it does not contain the GETPC_ADJ value. Likewise with GETPC_EXT to GETRA_EXT. Perform the GETPC_ADJ adjustment inside helper_ret_ld/st. This will allow backends to pass along the "true" return address rather than the massaged GETPC value. In the meantime, double application of GETPC_ADJ does not hurt, since the call insn in all ISAs is at least 4 bytes long. Reviewed-by: Aurelien Jarno Signed-off-by: Richard Henderson --- include/exec/exec-all.h | 84 +++++++++++++++++++---------------------- include/exec/softmmu_template.h | 24 ++++++++---- 2 files changed, 56 insertions(+), 52 deletions(-) diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index ffb69a4..6f71a4f 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -295,47 +295,42 @@ static inline void tb_add_jump(TranslationBlock *tb, int n, } } -/* The return address may point to the start of the next instruction. - Subtracting one gets us the call instruction itself. */ +/* GETRA is the true target of the return instruction that we'll execute, + defined here for simplicity of defining the follow-up macros. */ #if defined(CONFIG_TCG_INTERPRETER) extern uintptr_t tci_tb_ptr; -# define GETPC() tci_tb_ptr -#elif defined(__s390__) && !defined(__s390x__) -# define GETPC() \ - (((uintptr_t)__builtin_return_address(0) & 0x7fffffffUL) - 1) -#elif defined(__arm__) -/* Thumb return addresses have the low bit set, so we need to subtract two. - This is still safe in ARM mode because instructions are 4 bytes. */ -# define GETPC() ((uintptr_t)__builtin_return_address(0) - 2) +# define GETRA() tci_tb_ptr +#else +# define GETRA() \ + ((uintptr_t)__builtin_extract_return_addr(__builtin_return_address(0))) +#endif + +/* The true return address will often point to a host insn that is part of + the next translated guest insn. Adjust the address backward to point to + the middle of the call insn. Subtracting one would do the job except for + several compressed mode architectures (arm, mips) which set the low bit + to indicate the compressed mode; subtracting two works around that. It + is also the case that there are no host isas that contain a call insn + smaller than 4 bytes, so we don't worry about special-casing this. */ +#if defined(CONFIG_TCG_INTERPRETER) +# define GETPC_ADJ 0 #else -# define GETPC() ((uintptr_t)__builtin_return_address(0) - 1) +# define GETPC_ADJ 2 #endif +#define GETPC() (GETRA() - GETPC_ADJ) + +/* The LDST optimizations splits code generation into fast and slow path. + In some implementations, we pass the "logical" return address manually; + in others, we must infer the logical return from the true return. */ #if defined(CONFIG_QEMU_LDST_OPTIMIZATION) && defined(CONFIG_SOFTMMU) -/* qemu_ld/st optimization split code generation to fast and slow path, thus, - it needs special handling for an MMU helper which is called from the slow - path, to get the fast path's pc without any additional argument. - It uses a tricky solution which embeds the fast path pc into the slow path. - - Code flow in slow path: - (1) pre-process - (2) call MMU helper - (3) jump to (5) - (4) fast path information (implementation specific) - (5) post-process (e.g. stack adjust) - (6) jump to corresponding code of the next of fast path - */ -# if defined(__i386__) || defined(__x86_64__) -# define GETPC_EXT() GETPC() -# elif defined (_ARCH_PPC) && !defined (_ARCH_PPC64) -# define GETRA() ((uintptr_t)__builtin_return_address(0)) -# define GETPC_LDST() ((uintptr_t) ((*(int32_t *)(GETRA() - 4)) - 1)) +# if defined (_ARCH_PPC) && !defined (_ARCH_PPC64) +# define GETRA_LDST(RA) (*(int32_t *)((RA) - 4)) # elif defined(__arm__) /* We define two insns between the return address and the branch back to straight-line. Find and decode that branch insn. */ -# define GETRA() ((uintptr_t)__builtin_return_address(0)) -# define GETPC_LDST() tcg_getpc_ldst(GETRA()) -static inline uintptr_t tcg_getpc_ldst(uintptr_t ra) +# define GETRA_LDST(RA) tcg_getra_ldst(RA) +static inline uintptr_t tcg_getra_ldst(uintptr_t ra) { int32_t b; ra += 8; /* skip the two insns */ @@ -343,33 +338,32 @@ static inline uintptr_t tcg_getpc_ldst(uintptr_t ra) b = (b << 8) >> (8 - 2); /* extract the displacement */ ra += 8; /* branches are relative to pc+8 */ ra += b; /* apply the displacement */ - ra -= 4; /* return a pointer into the current opcode, - not the start of the next opcode */ return ra; } # elif defined(__aarch64__) -# define GETRA() ((uintptr_t)__builtin_return_address(0)) -# define GETPC_LDST() tcg_getpc_ldst(GETRA()) -static inline uintptr_t tcg_getpc_ldst(uintptr_t ra) +# define GETRA_LDST(RA) tcg_getra_ldst(RA) +static inline uintptr_t tcg_getra_ldst(uintptr_t ra) { int32_t b; ra += 4; /* skip one instruction */ b = *(int32_t *)ra; /* load the branch insn */ b = (b << 6) >> (6 - 2); /* extract the displacement */ ra += b; /* apply the displacement */ - ra -= 4; /* return a pointer into the current opcode, - not the start of the next opcode */ return ra; } -# else -# error "CONFIG_QEMU_LDST_OPTIMIZATION needs GETPC_LDST() implementation!" # endif +#endif /* CONFIG_QEMU_LDST_OPTIMIZATION */ + +/* ??? Delete these once they are no longer used. */ bool is_tcg_gen_code(uintptr_t pc_ptr); -# ifndef GETPC_EXT -# define GETPC_EXT() (is_tcg_gen_code(GETRA()) ? GETPC_LDST() : GETPC()) -# endif +#ifdef GETRA_LDST +# define GETRA_EXT() tcg_getra_ext(GETRA()) +static inline uintptr_t tcg_getra_ext(uintptr_t ra) +{ + return is_tcg_gen_code(ra) ? GETRA_LDST(ra) : ra; +} #else -# define GETPC_EXT() GETPC() +# define GETRA_EXT() GETRA() #endif #if !defined(CONFIG_USER_ONLY) diff --git a/include/exec/softmmu_template.h b/include/exec/softmmu_template.h index eaca9e1..2fc6ea3 100644 --- a/include/exec/softmmu_template.h +++ b/include/exec/softmmu_template.h @@ -86,6 +86,9 @@ glue(glue(helper_ret_ld, SUFFIX), MMUSUFFIX)(CPUArchState *env, target_ulong tlb_addr = env->tlb_table[mmu_idx][index].ADDR_READ; uintptr_t haddr; + /* Adjust the given return address. */ + retaddr -= GETPC_ADJ; + /* If the TLB entry is for a different page, reload and try again. */ if ((addr & TARGET_PAGE_MASK) != (tlb_addr & (TARGET_PAGE_MASK | TLB_INVALID_MASK))) { @@ -121,10 +124,12 @@ glue(glue(helper_ret_ld, SUFFIX), MMUSUFFIX)(CPUArchState *env, #endif addr1 = addr & ~(DATA_SIZE - 1); addr2 = addr1 + DATA_SIZE; - res1 = glue(glue(helper_ret_ld, SUFFIX), MMUSUFFIX)(env, addr1, - mmu_idx, retaddr); - res2 = glue(glue(helper_ret_ld, SUFFIX), MMUSUFFIX)(env, addr2, - mmu_idx, retaddr); + /* Note the adjustment at the beginning of the function. + Undo that for the recursion. */ + res1 = glue(glue(helper_ret_ld, SUFFIX), MMUSUFFIX) + (env, addr1, mmu_idx, retaddr + GETPC_ADJ); + res2 = glue(glue(helper_ret_ld, SUFFIX), MMUSUFFIX) + (env, addr2, mmu_idx, retaddr + GETPC_ADJ); shift = (addr & (DATA_SIZE - 1)) * 8; #ifdef TARGET_WORDS_BIGENDIAN res = (res1 << shift) | (res2 >> ((DATA_SIZE * 8) - shift)); @@ -150,7 +155,7 @@ glue(glue(helper_ld, SUFFIX), MMUSUFFIX)(CPUArchState *env, target_ulong addr, int mmu_idx) { return glue(glue(helper_ret_ld, SUFFIX), MMUSUFFIX)(env, addr, mmu_idx, - GETPC_EXT()); + GETRA_EXT()); } #ifndef SOFTMMU_CODE_ACCESS @@ -182,6 +187,9 @@ glue(glue(helper_ret_st, SUFFIX), MMUSUFFIX)(CPUArchState *env, target_ulong tlb_addr = env->tlb_table[mmu_idx][index].addr_write; uintptr_t haddr; + /* Adjust the given return address. */ + retaddr -= GETPC_ADJ; + /* If the TLB entry is for a different page, reload and try again. */ if ((addr & TARGET_PAGE_MASK) != (tlb_addr & (TARGET_PAGE_MASK | TLB_INVALID_MASK))) { @@ -223,8 +231,10 @@ glue(glue(helper_ret_st, SUFFIX), MMUSUFFIX)(CPUArchState *env, #else uint8_t val8 = val >> (i * 8); #endif + /* Note the adjustment at the beginning of the function. + Undo that for the recursion. */ glue(helper_ret_stb, MMUSUFFIX)(env, addr + i, val8, - mmu_idx, retaddr); + mmu_idx, retaddr + GETPC_ADJ); } return; } @@ -245,7 +255,7 @@ glue(glue(helper_st, SUFFIX), MMUSUFFIX)(CPUArchState *env, target_ulong addr, DATA_TYPE val, int mmu_idx) { glue(glue(helper_ret_st, SUFFIX), MMUSUFFIX)(env, addr, val, mmu_idx, - GETPC_EXT()); + GETRA_EXT()); } #endif /* !defined(SOFTMMU_CODE_ACCESS) */ -- 2.7.4