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| author | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 23:43:12 +0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 23:45:27 +0400 |
| commit | 63bcff2a307b9bcc712a8251eb27df8b2e117967 (patch) | |
| tree | 0a23a378d2c967edf63e9bb2b5df2288bf30859c /arch/x86/include/asm/uaccess.h | |
| parent | a052858fabb376b695f2c125633daa6728e0f284 (diff) | |
| download | linux-63bcff2a307b9bcc712a8251eb27df8b2e117967.tar.xz | |
x86, smap: Add STAC and CLAC instructions to control user space access
When Supervisor Mode Access Prevention (SMAP) is enabled, access to
userspace from the kernel is controlled by the AC flag. To make the
performance of manipulating that flag acceptable, there are two new
instructions, STAC and CLAC, to set and clear it.
This patch adds those instructions, via alternative(), when the SMAP
feature is enabled. It also adds X86_EFLAGS_AC unconditionally to the
SYSCALL entry mask; there is simply no reason to make that one
conditional.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1348256595-29119-9-git-send-email-hpa@linux.intel.com
Diffstat (limited to 'arch/x86/include/asm/uaccess.h')
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 2c7df3d184f2..b92ece13c238 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -9,6 +9,7 @@ #include <linux/string.h> #include <asm/asm.h> #include <asm/page.h> +#include <asm/smap.h> #define VERIFY_READ 0 #define VERIFY_WRITE 1 @@ -192,9 +193,10 @@ extern int __get_user_bad(void); #ifdef CONFIG_X86_32 #define __put_user_asm_u64(x, addr, err, errret) \ - asm volatile("1: movl %%eax,0(%2)\n" \ + asm volatile(ASM_STAC "\n" \ + "1: movl %%eax,0(%2)\n" \ "2: movl %%edx,4(%2)\n" \ - "3:\n" \ + "3: " ASM_CLAC "\n" \ ".section .fixup,\"ax\"\n" \ "4: movl %3,%0\n" \ " jmp 3b\n" \ @@ -205,9 +207,10 @@ extern int __get_user_bad(void); : "A" (x), "r" (addr), "i" (errret), "0" (err)) #define __put_user_asm_ex_u64(x, addr) \ - asm volatile("1: movl %%eax,0(%1)\n" \ + asm volatile(ASM_STAC "\n" \ + "1: movl %%eax,0(%1)\n" \ "2: movl %%edx,4(%1)\n" \ - "3:\n" \ + "3: " ASM_CLAC "\n" \ _ASM_EXTABLE_EX(1b, 2b) \ _ASM_EXTABLE_EX(2b, 3b) \ : : "A" (x), "r" (addr)) @@ -379,8 +382,9 @@ do { \ } while (0) #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \ - asm volatile("1: mov"itype" %2,%"rtype"1\n" \ - "2:\n" \ + asm volatile(ASM_STAC "\n" \ + "1: mov"itype" %2,%"rtype"1\n" \ + "2: " ASM_CLAC "\n" \ ".section .fixup,\"ax\"\n" \ "3: mov %3,%0\n" \ " xor"itype" %"rtype"1,%"rtype"1\n" \ @@ -412,8 +416,9 @@ do { \ } while (0) #define __get_user_asm_ex(x, addr, itype, rtype, ltype) \ - asm volatile("1: mov"itype" %1,%"rtype"0\n" \ - "2:\n" \ + asm volatile(ASM_STAC "\n" \ + "1: mov"itype" %1,%"rtype"0\n" \ + "2: " ASM_CLAC "\n" \ _ASM_EXTABLE_EX(1b, 2b) \ : ltype(x) : "m" (__m(addr))) @@ -443,8 +448,9 @@ struct __large_struct { unsigned long buf[100]; }; * aliasing issues. */ #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \ - asm volatile("1: mov"itype" %"rtype"1,%2\n" \ - "2:\n" \ + asm volatile(ASM_STAC "\n" \ + "1: mov"itype" %"rtype"1,%2\n" \ + "2: " ASM_CLAC "\n" \ ".section .fixup,\"ax\"\n" \ "3: mov %3,%0\n" \ " jmp 2b\n" \ @@ -454,8 +460,9 @@ struct __large_struct { unsigned long buf[100]; }; : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err)) #define __put_user_asm_ex(x, addr, itype, rtype, ltype) \ - asm volatile("1: mov"itype" %"rtype"0,%1\n" \ - "2:\n" \ + asm volatile(ASM_STAC "\n" \ + "1: mov"itype" %"rtype"0,%1\n" \ + "2: " ASM_CLAC "\n" \ _ASM_EXTABLE_EX(1b, 2b) \ : : ltype(x), "m" (__m(addr))) |