summaryrefslogtreecommitdiff
path: root/arch/x86/include/asm/uaccess.h
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2020-04-08 23:36:49 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 02:57:57 +0300
commitd55564cfc222326e944893eff0c4118353e349ec (patch)
tree03d846e223530c5ccbc89a3c516de67b8928926b /arch/x86/include/asm/uaccess.h
parentea6f043fc9847e670b91dfbf1ef1cdff3451c152 (diff)
downloadlinux-d55564cfc222326e944893eff0c4118353e349ec.tar.xz
x86: Make __put_user() generate an out-of-line call
Instead of inlining the stac/mov/clac sequence (which also requires individual exception table entries and several asm instruction alternatives entries), just generate "call __put_user_nocheck_X" for the __put_user() cases, the same way we changed __get_user earlier. Unlike the get_user() case, we didn't have the same nice infrastructure to just generate the call with a single case, so this actually has to change some of the infrastructure in order to do this. But that only cleans up the code further. So now, instead of using a case statement for the sizes, we just do the same thing we've done on the get_user() side for a long time: use the size as an immediate constant to the asm, and generate the asm that way directly. In order to handle the special case of 64-bit data on a 32-bit kernel, I needed to change the calling convention slightly: the data is passed in %eax[:%edx], the pointer in %ecx, and the return value is also returned in %ecx. It used to be returned in %eax, but because of how %eax can now be a double register input, we don't want mix that with a single-register output. The actual low-level asm is easier to handle: we'll just share the code between the checking and non-checking case, with the non-checking case jumping into the middle of the function. That may sound a bit too special, but this code is all very very special anyway, so... Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/include/asm/uaccess.h')
-rw-r--r--arch/x86/include/asm/uaccess.h119
1 files changed, 44 insertions, 75 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 600565fa246c..4c2f8bb32d78 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -201,11 +201,6 @@ extern int __get_user_bad(void);
*/
#define __get_user(x,ptr) do_get_user_call(get_user_nocheck,x,ptr)
-#define __put_user_x(size, x, ptr, __ret_pu) \
- asm volatile("call __put_user_" #size : "=a" (__ret_pu) \
- : "0" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
-
-
#ifdef CONFIG_X86_32
#define __put_user_goto_u64(x, addr, label) \
@@ -217,25 +212,41 @@ extern int __get_user_bad(void);
: : "A" (x), "r" (addr) \
: : label)
-#define __put_user_x8(x, ptr, __ret_pu) \
- asm volatile("call __put_user_8" : "=a" (__ret_pu) \
- : "A" ((typeof(*(ptr)))(x)), "c" (ptr) : "ebx")
#else
#define __put_user_goto_u64(x, ptr, label) \
__put_user_goto(x, ptr, "q", "er", label)
-#define __put_user_x8(x, ptr, __ret_pu) __put_user_x(8, x, ptr, __ret_pu)
#endif
extern void __put_user_bad(void);
/*
* Strange magic calling convention: pointer in %ecx,
- * value in %eax(:%edx), return value in %eax. clobbers %rbx
+ * value in %eax(:%edx), return value in %ecx. clobbers %rbx
*/
extern void __put_user_1(void);
extern void __put_user_2(void);
extern void __put_user_4(void);
extern void __put_user_8(void);
+extern void __put_user_nocheck_1(void);
+extern void __put_user_nocheck_2(void);
+extern void __put_user_nocheck_4(void);
+extern void __put_user_nocheck_8(void);
+
+#define do_put_user_call(fn,x,ptr) \
+({ \
+ int __ret_pu; \
+ register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \
+ __chk_user_ptr(ptr); \
+ __val_pu = (x); \
+ asm volatile("call __" #fn "_%P[size]" \
+ : "=c" (__ret_pu), \
+ ASM_CALL_CONSTRAINT \
+ : "0" (ptr), \
+ "r" (__val_pu), \
+ [size] "i" (sizeof(*(ptr))) \
+ :"ebx"); \
+ __builtin_expect(__ret_pu, 0); \
+})
/**
* put_user - Write a simple value into user space.
@@ -254,32 +265,29 @@ extern void __put_user_8(void);
*
* Return: zero on success, or -EFAULT on error.
*/
-#define put_user(x, ptr) \
-({ \
- int __ret_pu; \
- __typeof__(*(ptr)) __pu_val; \
- __chk_user_ptr(ptr); \
- might_fault(); \
- __pu_val = x; \
- switch (sizeof(*(ptr))) { \
- case 1: \
- __put_user_x(1, __pu_val, ptr, __ret_pu); \
- break; \
- case 2: \
- __put_user_x(2, __pu_val, ptr, __ret_pu); \
- break; \
- case 4: \
- __put_user_x(4, __pu_val, ptr, __ret_pu); \
- break; \
- case 8: \
- __put_user_x8(__pu_val, ptr, __ret_pu); \
- break; \
- default: \
- __put_user_x(X, __pu_val, ptr, __ret_pu); \
- break; \
- } \
- __builtin_expect(__ret_pu, 0); \
-})
+#define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); })
+
+/**
+ * __put_user - Write a simple value into user space, with less checking.
+ * @x: Value to copy to user space.
+ * @ptr: Destination address, in user space.
+ *
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
+ *
+ * This macro copies a single simple value from kernel space to user
+ * space. It supports simple types like char and int, but not larger
+ * data types like structures or arrays.
+ *
+ * @ptr must have pointer-to-simple-variable type, and @x must be assignable
+ * to the result of dereferencing @ptr.
+ *
+ * Caller must check the pointer with access_ok() before calling this
+ * function.
+ *
+ * Return: zero on success, or -EFAULT on error.
+ */
+#define __put_user(x, ptr) do_put_user_call(put_user_nocheck,x,ptr)
#define __put_user_size(x, ptr, size, label) \
do { \
@@ -370,21 +378,6 @@ do { \
: [umem] "m" (__m(addr)), \
[efault] "i" (-EFAULT), "0" (err))
-#define __put_user_nocheck(x, ptr, size) \
-({ \
- __label__ __pu_label; \
- int __pu_err = -EFAULT; \
- __typeof__(*(ptr)) __pu_val = (x); \
- __typeof__(ptr) __pu_ptr = (ptr); \
- __typeof__(size) __pu_size = (size); \
- __uaccess_begin(); \
- __put_user_size(__pu_val, __pu_ptr, __pu_size, __pu_label); \
- __pu_err = 0; \
-__pu_label: \
- __uaccess_end(); \
- __builtin_expect(__pu_err, 0); \
-})
-
/* FIXME: this hack is definitely wrong -AK */
struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct __user *)(x))
@@ -401,30 +394,6 @@ struct __large_struct { unsigned long buf[100]; };
: : ltype(x), "m" (__m(addr)) \
: : label)
-/**
- * __put_user - Write a simple value into user space, with less checking.
- * @x: Value to copy to user space.
- * @ptr: Destination address, in user space.
- *
- * Context: User context only. This function may sleep if pagefaults are
- * enabled.
- *
- * This macro copies a single simple value from kernel space to user
- * space. It supports simple types like char and int, but not larger
- * data types like structures or arrays.
- *
- * @ptr must have pointer-to-simple-variable type, and @x must be assignable
- * to the result of dereferencing @ptr.
- *
- * Caller must check the pointer with access_ok() before calling this
- * function.
- *
- * Return: zero on success, or -EFAULT on error.
- */
-
-#define __put_user(x, ptr) \
- __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))
-
extern unsigned long
copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
extern __must_check long