From 8ac6f5d7f84bf362e67591708bcb9788cdc42c50 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 11 Aug 2021 08:30:26 +0100 Subject: [PATCH] ARM: 9113/1: uaccess: remove set_fs() implementation There are no remaining callers of set_fs(), so just remove it along with all associated code that operates on thread_info->addr_limit. There are still further optimizations that can be done: - In get_user(), the address check could be moved entirely into the out of line code, rather than passing a constant as an argument, - I assume the DACR handling can be simplified as we now only change it during user access when CONFIG_CPU_SW_DOMAIN_PAN is set, but not during set_fs(). Acked-by: Christoph Hellwig Signed-off-by: Arnd Bergmann Signed-off-by: Russell King (Oracle) --- arch/arm/Kconfig | 1 - arch/arm/include/asm/ptrace.h | 1 - arch/arm/include/asm/thread_info.h | 4 ---- arch/arm/include/asm/uaccess-asm.h | 6 ----- arch/arm/include/asm/uaccess.h | 46 ++++---------------------------------- arch/arm/kernel/asm-offsets.c | 2 -- arch/arm/kernel/entry-common.S | 12 ---------- arch/arm/kernel/process.c | 7 +----- arch/arm/kernel/signal.c | 8 ------- arch/arm/lib/copy_from_user.S | 3 +-- arch/arm/lib/copy_to_user.S | 3 +-- 11 files changed, 7 insertions(+), 86 deletions(-) diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 3ea1c41..51897e4 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -126,7 +126,6 @@ config ARM select PCI_SYSCALL if PCI select PERF_USE_VMALLOC select RTC_LIB - select SET_FS select SYS_SUPPORTS_APM_EMULATION # Above selects are sorted alphabetically; please add new ones # according to that. Thanks. diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h index 91d6b78..93051e2 100644 --- a/arch/arm/include/asm/ptrace.h +++ b/arch/arm/include/asm/ptrace.h @@ -19,7 +19,6 @@ struct pt_regs { struct svc_pt_regs { struct pt_regs regs; u32 dacr; - u32 addr_limit; }; #define to_svc_pt_regs(r) container_of(r, struct svc_pt_regs, regs) diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index 17c5605..d89931a 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -31,8 +31,6 @@ struct task_struct; #include -typedef unsigned long mm_segment_t; - struct cpu_context_save { __u32 r4; __u32 r5; @@ -54,7 +52,6 @@ struct cpu_context_save { struct thread_info { unsigned long flags; /* low level flags */ int preempt_count; /* 0 => preemptable, <0 => bug */ - mm_segment_t addr_limit; /* address limit */ struct task_struct *task; /* main task structure */ __u32 cpu; /* cpu */ __u32 cpu_domain; /* cpu domain */ @@ -80,7 +77,6 @@ struct thread_info { .task = &tsk, \ .flags = 0, \ .preempt_count = INIT_PREEMPT_COUNT, \ - .addr_limit = KERNEL_DS, \ } /* diff --git a/arch/arm/include/asm/uaccess-asm.h b/arch/arm/include/asm/uaccess-asm.h index e6eb7a2..6451a43 100644 --- a/arch/arm/include/asm/uaccess-asm.h +++ b/arch/arm/include/asm/uaccess-asm.h @@ -84,12 +84,8 @@ * if \disable is set. */ .macro uaccess_entry, tsk, tmp0, tmp1, tmp2, disable - ldr \tmp1, [\tsk, #TI_ADDR_LIMIT] - ldr \tmp2, =TASK_SIZE - str \tmp2, [\tsk, #TI_ADDR_LIMIT] DACR( mrc p15, 0, \tmp0, c3, c0, 0) DACR( str \tmp0, [sp, #SVC_DACR]) - str \tmp1, [sp, #SVC_ADDR_LIMIT] .if \disable && IS_ENABLED(CONFIG_CPU_SW_DOMAIN_PAN) /* kernel=client, user=no access */ mov \tmp2, #DACR_UACCESS_DISABLE @@ -106,9 +102,7 @@ /* Restore the user access state previously saved by uaccess_entry */ .macro uaccess_exit, tsk, tmp0, tmp1 - ldr \tmp1, [sp, #SVC_ADDR_LIMIT] DACR( ldr \tmp0, [sp, #SVC_DACR]) - str \tmp1, [\tsk, #TI_ADDR_LIMIT] DACR( mcr p15, 0, \tmp0, c3, c0, 0) .endm diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 4f60638..084d1c0 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -52,32 +52,8 @@ static __always_inline void uaccess_restore(unsigned int flags) extern int __get_user_bad(void); extern int __put_user_bad(void); -/* - * Note that this is actually 0x1,0000,0000 - */ -#define KERNEL_DS 0x00000000 - #ifdef CONFIG_MMU -#define USER_DS TASK_SIZE -#define get_fs() (current_thread_info()->addr_limit) - -static inline void set_fs(mm_segment_t fs) -{ - current_thread_info()->addr_limit = fs; - - /* - * Prevent a mispredicted conditional call to set_fs from forwarding - * the wrong address limit to access_ok under speculation. - */ - dsb(nsh); - isb(); - - modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); -} - -#define uaccess_kernel() (get_fs() == KERNEL_DS) - /* * We use 33-bit arithmetic here. Success returns zero, failure returns * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS, @@ -89,7 +65,7 @@ static inline void set_fs(mm_segment_t fs) __asm__(".syntax unified\n" \ "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \ : "=&r" (flag), "=&r" (roksum) \ - : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ + : "r" (addr), "Ir" (size), "0" (TASK_SIZE) \ : "cc"); \ flag; }) @@ -120,7 +96,7 @@ static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, " subshs %1, %1, %2\n" " movlo %0, #0\n" : "+r" (safe_ptr), "=&r" (tmp) - : "r" (size), "r" (current_thread_info()->addr_limit) + : "r" (size), "r" (TASK_SIZE) : "cc"); csdb(); @@ -194,7 +170,7 @@ extern int __get_user_64t_4(void *); #define __get_user_check(x, p) \ ({ \ - unsigned long __limit = current_thread_info()->addr_limit - 1; \ + unsigned long __limit = TASK_SIZE - 1; \ register typeof(*(p)) __user *__p asm("r0") = (p); \ register __inttype(x) __r2 asm("r2"); \ register unsigned long __l asm("r1") = __limit; \ @@ -245,7 +221,7 @@ extern int __put_user_8(void *, unsigned long long); #define __put_user_check(__pu_val, __ptr, __err, __s) \ ({ \ - unsigned long __limit = current_thread_info()->addr_limit - 1; \ + unsigned long __limit = TASK_SIZE - 1; \ register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ register const void __user *__p asm("r0") = __ptr; \ register unsigned long __l asm("r1") = __limit; \ @@ -262,19 +238,8 @@ extern int __put_user_8(void *, unsigned long long); #else /* CONFIG_MMU */ -/* - * uClinux has only one addr space, so has simplified address limits. - */ -#define USER_DS KERNEL_DS - -#define uaccess_kernel() (true) #define __addr_ok(addr) ((void)(addr), 1) #define __range_ok(addr, size) ((void)(addr), 0) -#define get_fs() (KERNEL_DS) - -static inline void set_fs(mm_segment_t fs) -{ -} #define get_user(x, p) __get_user(x, p) #define __put_user_check __put_user_nocheck @@ -283,9 +248,6 @@ static inline void set_fs(mm_segment_t fs) #define access_ok(addr, size) (__range_ok(addr, size) == 0) -#define user_addr_max() \ - (uaccess_kernel() ? ~0UL : get_fs()) - #ifdef CONFIG_CPU_SPECTRE /* * When mitigating Spectre variant 1, it is not worth fixing the non- diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c index a0945b8..c60fefa 100644 --- a/arch/arm/kernel/asm-offsets.c +++ b/arch/arm/kernel/asm-offsets.c @@ -43,7 +43,6 @@ int main(void) BLANK(); DEFINE(TI_FLAGS, offsetof(struct thread_info, flags)); DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count)); - DEFINE(TI_ADDR_LIMIT, offsetof(struct thread_info, addr_limit)); DEFINE(TI_TASK, offsetof(struct thread_info, task)); DEFINE(TI_CPU, offsetof(struct thread_info, cpu)); DEFINE(TI_CPU_DOMAIN, offsetof(struct thread_info, cpu_domain)); @@ -92,7 +91,6 @@ int main(void) DEFINE(S_OLD_R0, offsetof(struct pt_regs, ARM_ORIG_r0)); DEFINE(PT_REGS_SIZE, sizeof(struct pt_regs)); DEFINE(SVC_DACR, offsetof(struct svc_pt_regs, dacr)); - DEFINE(SVC_ADDR_LIMIT, offsetof(struct svc_pt_regs, addr_limit)); DEFINE(SVC_REGS_SIZE, sizeof(struct svc_pt_regs)); BLANK(); DEFINE(SIGFRAME_RC3_OFFSET, offsetof(struct sigframe, retcode[3])); diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index e837af9..d9c99db 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -49,10 +49,6 @@ __ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) disable_irq_notrace @ disable interrupts - ldr r2, [tsk, #TI_ADDR_LIMIT] - ldr r1, =TASK_SIZE - cmp r2, r1 - blne addr_limit_check_failed ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing movs r1, r1, lsl #16 bne fast_work_pending @@ -87,10 +83,6 @@ __ret_fast_syscall: bl do_rseq_syscall #endif disable_irq_notrace @ disable interrupts - ldr r2, [tsk, #TI_ADDR_LIMIT] - ldr r1, =TASK_SIZE - cmp r2, r1 - blne addr_limit_check_failed ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing movs r1, r1, lsl #16 beq no_work_pending @@ -129,10 +121,6 @@ ret_slow_syscall: #endif disable_irq_notrace @ disable interrupts ENTRY(ret_to_user_from_irq) - ldr r2, [tsk, #TI_ADDR_LIMIT] - ldr r1, =TASK_SIZE - cmp r2, r1 - blne addr_limit_check_failed ldr r1, [tsk, #TI_FLAGS] movs r1, r1, lsl #16 bne slow_work_pending diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index fc9e8b3..581542f 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -108,7 +108,7 @@ void __show_regs(struct pt_regs *regs) unsigned long flags; char buf[64]; #ifndef CONFIG_CPU_V7M - unsigned int domain, fs; + unsigned int domain; #ifdef CONFIG_CPU_SW_DOMAIN_PAN /* * Get the domain register for the parent context. In user @@ -117,14 +117,11 @@ void __show_regs(struct pt_regs *regs) */ if (user_mode(regs)) { domain = DACR_UACCESS_ENABLE; - fs = get_fs(); } else { domain = to_svc_pt_regs(regs)->dacr; - fs = to_svc_pt_regs(regs)->addr_limit; } #else domain = get_domain(); - fs = get_fs(); #endif #endif @@ -160,8 +157,6 @@ void __show_regs(struct pt_regs *regs) if ((domain & domain_mask(DOMAIN_USER)) == domain_val(DOMAIN_USER, DOMAIN_NOACCESS)) segment = "none"; - else if (fs == KERNEL_DS) - segment = "kernel"; else segment = "user"; diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index a3a38d0..3e7ddac 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -711,14 +711,6 @@ struct page *get_signal_page(void) return page; } -/* Defer to generic check */ -asmlinkage void addr_limit_check_failed(void) -{ -#ifdef CONFIG_MMU - addr_limit_user_check(); -#endif -} - #ifdef CONFIG_DEBUG_RSEQ asmlinkage void do_rseq_syscall(struct pt_regs *regs) { diff --git a/arch/arm/lib/copy_from_user.S b/arch/arm/lib/copy_from_user.S index f8016e3..480a207 100644 --- a/arch/arm/lib/copy_from_user.S +++ b/arch/arm/lib/copy_from_user.S @@ -109,8 +109,7 @@ ENTRY(arm_copy_from_user) #ifdef CONFIG_CPU_SPECTRE - get_thread_info r3 - ldr r3, [r3, #TI_ADDR_LIMIT] + ldr r3, =TASK_SIZE uaccess_mask_range_ptr r1, r2, r3, ip #endif diff --git a/arch/arm/lib/copy_to_user.S b/arch/arm/lib/copy_to_user.S index ebfe4cb..842ea5e 100644 --- a/arch/arm/lib/copy_to_user.S +++ b/arch/arm/lib/copy_to_user.S @@ -109,8 +109,7 @@ ENTRY(__copy_to_user_std) WEAK(arm_copy_to_user) #ifdef CONFIG_CPU_SPECTRE - get_thread_info r3 - ldr r3, [r3, #TI_ADDR_LIMIT] + ldr r3, =TASK_SIZE uaccess_mask_range_ptr r0, r2, r3, ip #endif -- 2.7.4