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authorLinus Torvalds <torvalds@linux-foundation.org>2016-05-21 21:55:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-01-04 18:15:25 -0800
commita959dc88f9c8900296ccf13e2f3e1cbc555a8917 (patch)
tree8a8d5219ad5b7430107c92fe1ec3082611a5ce05
parent4a789213c9a54c8b618924d3421e56e98df8a447 (diff)
downloadlinux-a959dc88f9c8900296ccf13e2f3e1cbc555a8917.tar.gz
Use __put_user_goto in __put_user_size() and unsafe_put_user()
This actually enables the __put_user_goto() functionality in unsafe_put_user(). For an example of the effect of this, this is the code generated for the unsafe_put_user(signo, &infop->si_signo, Efault); in the waitid() system call: movl %ecx,(%rbx) # signo, MEM[(struct __large_struct *)_2] It's just one single store instruction, along with generating an exception table entry pointing to the Efault label case in case that instruction faults. Before, we would generate this: xorl %edx, %edx movl %ecx,(%rbx) # signo, MEM[(struct __large_struct *)_3] testl %edx, %edx jne .L309 with the exception table generated for that 'mov' instruction causing us to jump to a stub that set %edx to -EFAULT and then jumped back to the 'testl' instruction. So not only do we now get rid of the extra code in the normal sequence, we also avoid unnecessarily keeping that extra error register live across it all. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/include/asm/uaccess.h53
1 files changed, 22 insertions, 31 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 7328343e7204..a77445d1b034 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -186,19 +186,14 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
#ifdef CONFIG_X86_32
-#define __put_user_asm_u64(x, addr, err, errret) \
- asm volatile("\n" \
- "1: movl %%eax,0(%2)\n" \
- "2: movl %%edx,4(%2)\n" \
- "3:" \
- ".section .fixup,\"ax\"\n" \
- "4: movl %3,%0\n" \
- " jmp 3b\n" \
- ".previous\n" \
- _ASM_EXTABLE_UA(1b, 4b) \
- _ASM_EXTABLE_UA(2b, 4b) \
- : "=r" (err) \
- : "A" (x), "r" (addr), "i" (errret), "0" (err))
+#define __put_user_goto_u64(x, addr, label) \
+ asm_volatile_goto("\n" \
+ "1: movl %%eax,0(%1)\n" \
+ "2: movl %%edx,4(%1)\n" \
+ _ASM_EXTABLE_UA(1b, %l2) \
+ _ASM_EXTABLE_UA(2b, %l2) \
+ : : "A" (x), "r" (addr) \
+ : : label)
#define __put_user_asm_ex_u64(x, addr) \
asm volatile("\n" \
@@ -213,8 +208,8 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
asm volatile("call __put_user_8" : "=a" (__ret_pu) \
: "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
#else
-#define __put_user_asm_u64(x, ptr, retval, errret) \
- __put_user_asm(x, ptr, retval, "q", "", "er", errret)
+#define __put_user_goto_u64(x, ptr, label) \
+ __put_user_goto(x, ptr, "q", "", "er", label)
#define __put_user_asm_ex_u64(x, addr) \
__put_user_asm_ex(x, addr, "q", "", "er")
#define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
@@ -275,23 +270,21 @@ extern void __put_user_8(void);
__builtin_expect(__ret_pu, 0); \
})
-#define __put_user_size(x, ptr, size, retval, errret) \
+#define __put_user_size(x, ptr, size, label) \
do { \
- retval = 0; \
__chk_user_ptr(ptr); \
switch (size) { \
case 1: \
- __put_user_asm(x, ptr, retval, "b", "b", "iq", errret); \
+ __put_user_goto(x, ptr, "b", "b", "iq", label); \
break; \
case 2: \
- __put_user_asm(x, ptr, retval, "w", "w", "ir", errret); \
+ __put_user_goto(x, ptr, "w", "w", "ir", label); \
break; \
case 4: \
- __put_user_asm(x, ptr, retval, "l", "k", "ir", errret); \
+ __put_user_goto(x, ptr, "l", "k", "ir", label); \
break; \
case 8: \
- __put_user_asm_u64((__typeof__(*ptr))(x), ptr, retval, \
- errret); \
+ __put_user_goto_u64((__typeof__(*ptr))(x), ptr, label); \
break; \
default: \
__put_user_bad(); \
@@ -436,9 +429,12 @@ do { \
#define __put_user_nocheck(x, ptr, size) \
({ \
- int __pu_err; \
+ __label__ __pu_label; \
+ int __pu_err = -EFAULT; \
__uaccess_begin(); \
- __put_user_size((x), (ptr), (size), __pu_err, -EFAULT); \
+ __put_user_size((x), (ptr), (size), __pu_label); \
+ __pu_err = 0; \
+__pu_label: \
__uaccess_end(); \
__builtin_expect(__pu_err, 0); \
})
@@ -721,13 +717,8 @@ static __must_check inline bool user_access_begin(const void __user *ptr, size_t
#define user_access_begin(a,b) user_access_begin(a,b)
#define user_access_end() __uaccess_end()
-#define unsafe_put_user(x, ptr, err_label) \
-do { \
- int __pu_err; \
- __typeof__(*(ptr)) __pu_val = (x); \
- __put_user_size(__pu_val, (ptr), sizeof(*(ptr)), __pu_err, -EFAULT); \
- if (unlikely(__pu_err)) goto err_label; \
-} while (0)
+#define unsafe_put_user(x, ptr, label) \
+ __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
#define unsafe_get_user(x, ptr, err_label) \
do { \