diff options
author | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 19:43:12 (GMT) |
---|---|---|
committer | H. Peter Anvin <hpa@linux.intel.com> | 2012-09-21 19:45:27 (GMT) |
commit | 63bcff2a307b9bcc712a8251eb27df8b2e117967 (patch) | |
tree | 0a23a378d2c967edf63e9bb2b5df2288bf30859c /arch/x86/lib | |
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/lib')
-rw-r--r-- | arch/x86/lib/copy_user_64.S | 7 | ||||
-rw-r--r-- | arch/x86/lib/copy_user_nocache_64.S | 3 | ||||
-rw-r--r-- | arch/x86/lib/getuser.S | 10 | ||||
-rw-r--r-- | arch/x86/lib/putuser.S | 8 | ||||
-rw-r--r-- | arch/x86/lib/usercopy_32.c | 13 | ||||
-rw-r--r-- | arch/x86/lib/usercopy_64.c | 3 |
6 files changed, 42 insertions, 2 deletions
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S index 5b2995f..a30ca15 100644 --- a/arch/x86/lib/copy_user_64.S +++ b/arch/x86/lib/copy_user_64.S @@ -17,6 +17,7 @@ #include <asm/cpufeature.h> #include <asm/alternative-asm.h> #include <asm/asm.h> +#include <asm/smap.h> /* * By placing feature2 after feature1 in altinstructions section, we logically @@ -130,6 +131,7 @@ ENDPROC(bad_from_user) */ ENTRY(copy_user_generic_unrolled) CFI_STARTPROC + ASM_STAC cmpl $8,%edx jb 20f /* less then 8 bytes, go to byte copy loop */ ALIGN_DESTINATION @@ -177,6 +179,7 @@ ENTRY(copy_user_generic_unrolled) decl %ecx jnz 21b 23: xor %eax,%eax + ASM_CLAC ret .section .fixup,"ax" @@ -232,6 +235,7 @@ ENDPROC(copy_user_generic_unrolled) */ ENTRY(copy_user_generic_string) CFI_STARTPROC + ASM_STAC andl %edx,%edx jz 4f cmpl $8,%edx @@ -246,6 +250,7 @@ ENTRY(copy_user_generic_string) 3: rep movsb 4: xorl %eax,%eax + ASM_CLAC ret .section .fixup,"ax" @@ -273,12 +278,14 @@ ENDPROC(copy_user_generic_string) */ ENTRY(copy_user_enhanced_fast_string) CFI_STARTPROC + ASM_STAC andl %edx,%edx jz 2f movl %edx,%ecx 1: rep movsb 2: xorl %eax,%eax + ASM_CLAC ret .section .fixup,"ax" diff --git a/arch/x86/lib/copy_user_nocache_64.S b/arch/x86/lib/copy_user_nocache_64.S index cacddc7..6a4f43c 100644 --- a/arch/x86/lib/copy_user_nocache_64.S +++ b/arch/x86/lib/copy_user_nocache_64.S @@ -15,6 +15,7 @@ #include <asm/asm-offsets.h> #include <asm/thread_info.h> #include <asm/asm.h> +#include <asm/smap.h> .macro ALIGN_DESTINATION #ifdef FIX_ALIGNMENT @@ -48,6 +49,7 @@ */ ENTRY(__copy_user_nocache) CFI_STARTPROC + ASM_STAC cmpl $8,%edx jb 20f /* less then 8 bytes, go to byte copy loop */ ALIGN_DESTINATION @@ -95,6 +97,7 @@ ENTRY(__copy_user_nocache) decl %ecx jnz 21b 23: xorl %eax,%eax + ASM_CLAC sfence ret diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S index b33b1fb..156b9c8 100644 --- a/arch/x86/lib/getuser.S +++ b/arch/x86/lib/getuser.S @@ -33,6 +33,7 @@ #include <asm/asm-offsets.h> #include <asm/thread_info.h> #include <asm/asm.h> +#include <asm/smap.h> .text ENTRY(__get_user_1) @@ -40,8 +41,10 @@ ENTRY(__get_user_1) GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user + ASM_STAC 1: movzb (%_ASM_AX),%edx xor %eax,%eax + ASM_CLAC ret CFI_ENDPROC ENDPROC(__get_user_1) @@ -53,8 +56,10 @@ ENTRY(__get_user_2) GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user + ASM_STAC 2: movzwl -1(%_ASM_AX),%edx xor %eax,%eax + ASM_CLAC ret CFI_ENDPROC ENDPROC(__get_user_2) @@ -66,8 +71,10 @@ ENTRY(__get_user_4) GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user + ASM_STAC 3: mov -3(%_ASM_AX),%edx xor %eax,%eax + ASM_CLAC ret CFI_ENDPROC ENDPROC(__get_user_4) @@ -80,8 +87,10 @@ ENTRY(__get_user_8) GET_THREAD_INFO(%_ASM_DX) cmp TI_addr_limit(%_ASM_DX),%_ASM_AX jae bad_get_user + ASM_STAC 4: movq -7(%_ASM_AX),%_ASM_DX xor %eax,%eax + ASM_CLAC ret CFI_ENDPROC ENDPROC(__get_user_8) @@ -91,6 +100,7 @@ bad_get_user: CFI_STARTPROC xor %edx,%edx mov $(-EFAULT),%_ASM_AX + ASM_CLAC ret CFI_ENDPROC END(bad_get_user) diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S index 7f951c8..fc6ba17 100644 --- a/arch/x86/lib/putuser.S +++ b/arch/x86/lib/putuser.S @@ -15,6 +15,7 @@ #include <asm/thread_info.h> #include <asm/errno.h> #include <asm/asm.h> +#include <asm/smap.h> /* @@ -31,7 +32,8 @@ #define ENTER CFI_STARTPROC ; \ GET_THREAD_INFO(%_ASM_BX) -#define EXIT ret ; \ +#define EXIT ASM_CLAC ; \ + ret ; \ CFI_ENDPROC .text @@ -39,6 +41,7 @@ ENTRY(__put_user_1) ENTER cmp TI_addr_limit(%_ASM_BX),%_ASM_CX jae bad_put_user + ASM_STAC 1: movb %al,(%_ASM_CX) xor %eax,%eax EXIT @@ -50,6 +53,7 @@ ENTRY(__put_user_2) sub $1,%_ASM_BX cmp %_ASM_BX,%_ASM_CX jae bad_put_user + ASM_STAC 2: movw %ax,(%_ASM_CX) xor %eax,%eax EXIT @@ -61,6 +65,7 @@ ENTRY(__put_user_4) sub $3,%_ASM_BX cmp %_ASM_BX,%_ASM_CX jae bad_put_user + ASM_STAC 3: movl %eax,(%_ASM_CX) xor %eax,%eax EXIT @@ -72,6 +77,7 @@ ENTRY(__put_user_8) sub $7,%_ASM_BX cmp %_ASM_BX,%_ASM_CX jae bad_put_user + ASM_STAC 4: mov %_ASM_AX,(%_ASM_CX) #ifdef CONFIG_X86_32 5: movl %edx,4(%_ASM_CX) diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c index 1781b2f..98f6d6b6 100644 --- a/arch/x86/lib/usercopy_32.c +++ b/arch/x86/lib/usercopy_32.c @@ -42,10 +42,11 @@ do { \ int __d0; \ might_fault(); \ __asm__ __volatile__( \ + ASM_STAC "\n" \ "0: rep; stosl\n" \ " movl %2,%0\n" \ "1: rep; stosb\n" \ - "2:\n" \ + "2: " ASM_CLAC "\n" \ ".section .fixup,\"ax\"\n" \ "3: lea 0(%2,%0,4),%0\n" \ " jmp 2b\n" \ @@ -626,10 +627,12 @@ survive: return n; } #endif + stac(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else n = __copy_user_intel(to, from, n); + clac(); return n; } EXPORT_SYMBOL(__copy_to_user_ll); @@ -637,10 +640,12 @@ EXPORT_SYMBOL(__copy_to_user_ll); unsigned long __copy_from_user_ll(void *to, const void __user *from, unsigned long n) { + stac(); if (movsl_is_ok(to, from, n)) __copy_user_zeroing(to, from, n); else n = __copy_user_zeroing_intel(to, from, n); + clac(); return n; } EXPORT_SYMBOL(__copy_from_user_ll); @@ -648,11 +653,13 @@ EXPORT_SYMBOL(__copy_from_user_ll); unsigned long __copy_from_user_ll_nozero(void *to, const void __user *from, unsigned long n) { + stac(); if (movsl_is_ok(to, from, n)) __copy_user(to, from, n); else n = __copy_user_intel((void __user *)to, (const void *)from, n); + clac(); return n; } EXPORT_SYMBOL(__copy_from_user_ll_nozero); @@ -660,6 +667,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nozero); unsigned long __copy_from_user_ll_nocache(void *to, const void __user *from, unsigned long n) { + stac(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_zeroing_intel_nocache(to, from, n); @@ -668,6 +676,7 @@ unsigned long __copy_from_user_ll_nocache(void *to, const void __user *from, #else __copy_user_zeroing(to, from, n); #endif + clac(); return n; } EXPORT_SYMBOL(__copy_from_user_ll_nocache); @@ -675,6 +684,7 @@ EXPORT_SYMBOL(__copy_from_user_ll_nocache); unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from, unsigned long n) { + stac(); #ifdef CONFIG_X86_INTEL_USERCOPY if (n > 64 && cpu_has_xmm2) n = __copy_user_intel_nocache(to, from, n); @@ -683,6 +693,7 @@ unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *fr #else __copy_user(to, from, n); #endif + clac(); return n; } EXPORT_SYMBOL(__copy_from_user_ll_nocache_nozero); diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index e5b130b..05928aa 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -18,6 +18,7 @@ unsigned long __clear_user(void __user *addr, unsigned long size) might_fault(); /* no memory constraint because it doesn't change any memory gcc knows about */ + stac(); asm volatile( " testq %[size8],%[size8]\n" " jz 4f\n" @@ -40,6 +41,7 @@ unsigned long __clear_user(void __user *addr, unsigned long size) : [size8] "=&c"(size), [dst] "=&D" (__d0) : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr), [zero] "r" (0UL), [eight] "r" (8UL)); + clac(); return size; } EXPORT_SYMBOL(__clear_user); @@ -82,5 +84,6 @@ copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest) for (c = 0, zero_len = len; zerorest && zero_len; --zero_len) if (__put_user_nocheck(c, to++, sizeof(char))) break; + clac(); return len; } |