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
This commit is contained in:
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a052858fab
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63bcff2a30
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@ -14,6 +14,7 @@
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#include <asm/segment.h>
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#include <asm/irqflags.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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#include <linux/linkage.h>
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#include <linux/err.h>
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@ -146,8 +147,10 @@ ENTRY(ia32_sysenter_target)
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SAVE_ARGS 0,1,0
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/* no need to do an access_ok check here because rbp has been
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32bit zero extended */
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ASM_STAC
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1: movl (%rbp),%ebp
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_ASM_EXTABLE(1b,ia32_badarg)
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ASM_CLAC
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orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP-ARGOFFSET)
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testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
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CFI_REMEMBER_STATE
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@ -301,8 +304,10 @@ ENTRY(ia32_cstar_target)
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/* no need to do an access_ok check here because r8 has been
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32bit zero extended */
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/* hardware stack frame is complete now */
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ASM_STAC
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1: movl (%r8),%r9d
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_ASM_EXTABLE(1b,ia32_badarg)
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ASM_CLAC
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orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP-ARGOFFSET)
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testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
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CFI_REMEMBER_STATE
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@ -365,6 +370,7 @@ cstar_tracesys:
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END(ia32_cstar_target)
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ia32_badarg:
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ASM_CLAC
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movq $-EFAULT,%rax
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jmp ia32_sysret
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CFI_ENDPROC
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@ -126,8 +126,9 @@ static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
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/* See comment in fxsave() below. */
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#ifdef CONFIG_AS_FXSAVEQ
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asm volatile("1: fxsaveq %[fx]\n\t"
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"2:\n"
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asm volatile(ASM_STAC "\n"
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"1: fxsaveq %[fx]\n\t"
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"2: " ASM_CLAC "\n"
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".section .fixup,\"ax\"\n"
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"3: movl $-1,%[err]\n"
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" jmp 2b\n"
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@ -136,8 +137,9 @@ static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
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: [err] "=r" (err), [fx] "=m" (*fx)
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: "0" (0));
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#else
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asm volatile("1: rex64/fxsave (%[fx])\n\t"
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"2:\n"
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asm volatile(ASM_STAC "\n"
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"1: rex64/fxsave (%[fx])\n\t"
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"2: " ASM_CLAC "\n"
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".section .fixup,\"ax\"\n"
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"3: movl $-1,%[err]\n"
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" jmp 2b\n"
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@ -9,10 +9,13 @@
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#include <asm/asm.h>
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#include <asm/errno.h>
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#include <asm/processor.h>
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#include <asm/smap.h>
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#define __futex_atomic_op1(insn, ret, oldval, uaddr, oparg) \
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asm volatile("1:\t" insn "\n" \
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"2:\t.section .fixup,\"ax\"\n" \
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asm volatile("\t" ASM_STAC "\n" \
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"1:\t" insn "\n" \
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"2:\t" ASM_CLAC "\n" \
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"\t.section .fixup,\"ax\"\n" \
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"3:\tmov\t%3, %1\n" \
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"\tjmp\t2b\n" \
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"\t.previous\n" \
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@ -21,12 +24,14 @@
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: "i" (-EFAULT), "0" (oparg), "1" (0))
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#define __futex_atomic_op2(insn, ret, oldval, uaddr, oparg) \
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asm volatile("1:\tmovl %2, %0\n" \
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asm volatile("\t" ASM_STAC "\n" \
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"1:\tmovl %2, %0\n" \
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"\tmovl\t%0, %3\n" \
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"\t" insn "\n" \
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"2:\t" LOCK_PREFIX "cmpxchgl %3, %2\n" \
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"\tjnz\t1b\n" \
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"3:\t.section .fixup,\"ax\"\n" \
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"3:\t" ASM_CLAC "\n" \
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"\t.section .fixup,\"ax\"\n" \
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"4:\tmov\t%5, %1\n" \
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"\tjmp\t3b\n" \
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"\t.previous\n" \
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@ -122,8 +127,10 @@ static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
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if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
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return -EFAULT;
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asm volatile("1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
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"2:\t.section .fixup, \"ax\"\n"
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asm volatile("\t" ASM_STAC "\n"
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"1:\t" LOCK_PREFIX "cmpxchgl %4, %2\n"
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"2:\t" ASM_CLAC "\n"
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"\t.section .fixup, \"ax\"\n"
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"3:\tmov %3, %0\n"
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"\tjmp 2b\n"
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"\t.previous\n"
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@ -58,13 +58,13 @@
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#ifdef CONFIG_X86_SMAP
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static inline void clac(void)
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static __always_inline void clac(void)
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{
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/* Note: a barrier is implicit in alternative() */
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alternative(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
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}
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static inline void stac(void)
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static __always_inline void stac(void)
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{
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/* Note: a barrier is implicit in alternative() */
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alternative(ASM_NOP3, __stringify(__ASM_STAC), X86_FEATURE_SMAP);
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@ -9,6 +9,7 @@
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#include <linux/string.h>
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#include <asm/asm.h>
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#include <asm/page.h>
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#include <asm/smap.h>
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#define VERIFY_READ 0
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#define VERIFY_WRITE 1
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@ -192,9 +193,10 @@ extern int __get_user_bad(void);
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#ifdef CONFIG_X86_32
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#define __put_user_asm_u64(x, addr, err, errret) \
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asm volatile("1: movl %%eax,0(%2)\n" \
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asm volatile(ASM_STAC "\n" \
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"1: movl %%eax,0(%2)\n" \
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"2: movl %%edx,4(%2)\n" \
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"3:\n" \
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"3: " ASM_CLAC "\n" \
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".section .fixup,\"ax\"\n" \
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"4: movl %3,%0\n" \
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" jmp 3b\n" \
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@ -205,9 +207,10 @@ extern int __get_user_bad(void);
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: "A" (x), "r" (addr), "i" (errret), "0" (err))
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#define __put_user_asm_ex_u64(x, addr) \
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asm volatile("1: movl %%eax,0(%1)\n" \
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asm volatile(ASM_STAC "\n" \
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"1: movl %%eax,0(%1)\n" \
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"2: movl %%edx,4(%1)\n" \
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"3:\n" \
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"3: " ASM_CLAC "\n" \
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_ASM_EXTABLE_EX(1b, 2b) \
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_ASM_EXTABLE_EX(2b, 3b) \
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: : "A" (x), "r" (addr))
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@ -379,8 +382,9 @@ do { \
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} while (0)
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#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \
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asm volatile("1: mov"itype" %2,%"rtype"1\n" \
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"2:\n" \
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asm volatile(ASM_STAC "\n" \
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"1: mov"itype" %2,%"rtype"1\n" \
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"2: " ASM_CLAC "\n" \
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".section .fixup,\"ax\"\n" \
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"3: mov %3,%0\n" \
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" xor"itype" %"rtype"1,%"rtype"1\n" \
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@ -412,8 +416,9 @@ do { \
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} while (0)
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#define __get_user_asm_ex(x, addr, itype, rtype, ltype) \
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asm volatile("1: mov"itype" %1,%"rtype"0\n" \
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"2:\n" \
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asm volatile(ASM_STAC "\n" \
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"1: mov"itype" %1,%"rtype"0\n" \
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"2: " ASM_CLAC "\n" \
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_ASM_EXTABLE_EX(1b, 2b) \
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: ltype(x) : "m" (__m(addr)))
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* aliasing issues.
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*/
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#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \
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asm volatile("1: mov"itype" %"rtype"1,%2\n" \
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"2:\n" \
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asm volatile(ASM_STAC "\n" \
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"1: mov"itype" %"rtype"1,%2\n" \
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"2: " ASM_CLAC "\n" \
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".section .fixup,\"ax\"\n" \
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"3: mov %3,%0\n" \
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" jmp 2b\n" \
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: ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))
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#define __put_user_asm_ex(x, addr, itype, rtype, ltype) \
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asm volatile("1: mov"itype" %"rtype"0,%1\n" \
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"2:\n" \
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asm volatile(ASM_STAC "\n" \
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"1: mov"itype" %"rtype"0,%1\n" \
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"2: " ASM_CLAC "\n" \
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_ASM_EXTABLE_EX(1b, 2b) \
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: : ltype(x), "m" (__m(addr)))
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@ -74,8 +74,9 @@ static inline int xsave_user(struct xsave_struct __user *buf)
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if (unlikely(err))
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return -EFAULT;
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__asm__ __volatile__("1: .byte " REX_PREFIX "0x0f,0xae,0x27\n"
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"2:\n"
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__asm__ __volatile__(ASM_STAC "\n"
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"1: .byte " REX_PREFIX "0x0f,0xae,0x27\n"
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"2: " ASM_CLAC "\n"
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".section .fixup,\"ax\"\n"
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"3: movl $-1,%[err]\n"
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" jmp 2b\n"
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u32 lmask = mask;
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u32 hmask = mask >> 32;
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__asm__ __volatile__("1: .byte " REX_PREFIX "0x0f,0xae,0x2f\n"
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"2:\n"
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__asm__ __volatile__(ASM_STAC "\n"
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"1: .byte " REX_PREFIX "0x0f,0xae,0x2f\n"
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"2: " ASM_CLAC "\n"
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".section .fixup,\"ax\"\n"
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"3: movl $-1,%[err]\n"
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" jmp 2b\n"
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@ -1113,7 +1113,8 @@ void syscall_init(void)
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/* Flags to clear on syscall */
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wrmsrl(MSR_SYSCALL_MASK,
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X86_EFLAGS_TF|X86_EFLAGS_DF|X86_EFLAGS_IF|X86_EFLAGS_IOPL);
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X86_EFLAGS_TF|X86_EFLAGS_DF|X86_EFLAGS_IF|
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X86_EFLAGS_IOPL|X86_EFLAGS_AC);
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}
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unsigned long kernel_eflags;
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@ -56,6 +56,7 @@
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#include <asm/ftrace.h>
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#include <asm/percpu.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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#include <linux/err.h>
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/* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this. */
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* System call entry. Up to 6 arguments in registers are supported.
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*
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* SYSCALL does not save anything on the stack and does not change the
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* stack pointer.
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* stack pointer. However, it does mask the flags register for us, so
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* CLD and CLAC are not needed.
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*/
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/*
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*/
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.p2align CONFIG_X86_L1_CACHE_SHIFT
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common_interrupt:
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ASM_CLAC
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XCPT_FRAME
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addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
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interrupt do_IRQ
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*/
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.macro apicinterrupt num sym do_sym
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ENTRY(\sym)
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ASM_CLAC
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INTR_FRAME
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pushq_cfi $~(\num)
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.Lcommon_\sym:
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*/
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.macro zeroentry sym do_sym
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ENTRY(\sym)
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ASM_CLAC
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INTR_FRAME
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PARAVIRT_ADJUST_EXCEPTION_FRAME
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pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
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.macro paranoidzeroentry sym do_sym
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ENTRY(\sym)
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ASM_CLAC
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INTR_FRAME
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PARAVIRT_ADJUST_EXCEPTION_FRAME
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pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
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@ -1112,6 +1118,7 @@ END(\sym)
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#define INIT_TSS_IST(x) PER_CPU_VAR(init_tss) + (TSS_ist + ((x) - 1) * 8)
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.macro paranoidzeroentry_ist sym do_sym ist
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ENTRY(\sym)
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ASM_CLAC
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INTR_FRAME
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PARAVIRT_ADJUST_EXCEPTION_FRAME
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pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
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@ -1131,6 +1138,7 @@ END(\sym)
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.macro errorentry sym do_sym
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ENTRY(\sym)
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ASM_CLAC
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XCPT_FRAME
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PARAVIRT_ADJUST_EXCEPTION_FRAME
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subq $ORIG_RAX-R15, %rsp
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/* error code is on the stack already */
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.macro paranoiderrorentry sym do_sym
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ENTRY(\sym)
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ASM_CLAC
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XCPT_FRAME
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PARAVIRT_ADJUST_EXCEPTION_FRAME
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subq $ORIG_RAX-R15, %rsp
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@ -17,6 +17,7 @@
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#include <asm/cpufeature.h>
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#include <asm/alternative-asm.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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/*
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* By placing feature2 after feature1 in altinstructions section, we logically
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@ -130,6 +131,7 @@ ENDPROC(bad_from_user)
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*/
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ENTRY(copy_user_generic_unrolled)
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CFI_STARTPROC
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ASM_STAC
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cmpl $8,%edx
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jb 20f /* less then 8 bytes, go to byte copy loop */
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ALIGN_DESTINATION
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@ -177,6 +179,7 @@ ENTRY(copy_user_generic_unrolled)
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decl %ecx
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jnz 21b
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23: xor %eax,%eax
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ASM_CLAC
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ret
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.section .fixup,"ax"
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@ -232,6 +235,7 @@ ENDPROC(copy_user_generic_unrolled)
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*/
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ENTRY(copy_user_generic_string)
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CFI_STARTPROC
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ASM_STAC
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andl %edx,%edx
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jz 4f
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cmpl $8,%edx
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@ -246,6 +250,7 @@ ENTRY(copy_user_generic_string)
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3: rep
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movsb
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4: xorl %eax,%eax
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ASM_CLAC
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ret
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.section .fixup,"ax"
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@ -273,12 +278,14 @@ ENDPROC(copy_user_generic_string)
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*/
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ENTRY(copy_user_enhanced_fast_string)
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CFI_STARTPROC
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ASM_STAC
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andl %edx,%edx
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jz 2f
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movl %edx,%ecx
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1: rep
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movsb
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2: xorl %eax,%eax
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ASM_CLAC
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ret
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.section .fixup,"ax"
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@ -15,6 +15,7 @@
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#include <asm/asm-offsets.h>
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#include <asm/thread_info.h>
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#include <asm/asm.h>
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#include <asm/smap.h>
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.macro ALIGN_DESTINATION
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#ifdef FIX_ALIGNMENT
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@ -48,6 +49,7 @@
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*/
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ENTRY(__copy_user_nocache)
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CFI_STARTPROC
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ASM_STAC
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cmpl $8,%edx
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jb 20f /* less then 8 bytes, go to byte copy loop */
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ALIGN_DESTINATION
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@ -95,6 +97,7 @@ ENTRY(__copy_user_nocache)
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decl %ecx
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jnz 21b
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23: xorl %eax,%eax
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ASM_CLAC
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sfence
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ret
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@ -33,6 +33,7 @@
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#include <asm/asm-offsets.h>
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#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)
|
||||
|
|
|
@ -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)
|
||||
|
|
|
@ -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);
|
||||
|
|
|
@ -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;
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue