[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 5/9] x86: Temporary disable SMAP to legally access user pages in kernel mode
Use STAC/CLAC to temporarily disable SMAP to allow legal accesses to user pages in kernel mode Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx> --- xen/arch/x86/traps.c | 2 ++ xen/arch/x86/usercopy.c | 6 ++++++ xen/arch/x86/x86_64/compat/entry.S | 2 ++ xen/arch/x86/x86_64/entry.S | 2 ++ xen/include/asm-x86/uaccess.h | 4 ++++ xen/include/asm-x86/x86_64/system.h | 2 ++ 6 files changed, 18 insertions(+) diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index ed4ae2d..1b0dc1a 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -3754,6 +3754,8 @@ unsigned long do_get_debugreg(int reg) void asm_domain_crash_synchronous(unsigned long addr) { + clac(); + if ( addr == 0 ) addr = this_cpu(last_extable_addr); diff --git a/xen/arch/x86/usercopy.c b/xen/arch/x86/usercopy.c index b79202b..af96bf4 100644 --- a/xen/arch/x86/usercopy.c +++ b/xen/arch/x86/usercopy.c @@ -15,6 +15,7 @@ unsigned long __copy_to_user_ll(void __user *to, const void *from, unsigned n) unsigned long __d0, __d1, __d2, __n = n; asm volatile ( + ASM_STAC"\n" " cmp $"STR(2*BYTES_PER_LONG-1)",%0\n" " jbe 1f\n" " mov %1,%0\n" @@ -30,6 +31,7 @@ unsigned long __copy_to_user_ll(void __user *to, const void *from, unsigned n) " mov %3,%0\n" "1: rep movsb\n" /* ...remainder copied as bytes */ "2:\n" + ASM_CLAC"\n" ".section .fixup,\"ax\"\n" "5: add %3,%0\n" " jmp 2b\n" @@ -52,6 +54,7 @@ __copy_from_user_ll(void *to, const void __user *from, unsigned n) unsigned long __d0, __d1, __d2, __n = n; asm volatile ( + ASM_STAC"\n" " cmp $"STR(2*BYTES_PER_LONG-1)",%0\n" " jbe 1f\n" " mov %1,%0\n" @@ -67,6 +70,7 @@ __copy_from_user_ll(void *to, const void __user *from, unsigned n) " mov %3,%0\n" "1: rep; movsb\n" /* ...remainder copied as bytes */ "2:\n" + ASM_CLAC"\n" ".section .fixup,\"ax\"\n" "5: add %3,%0\n" " jmp 6f\n" @@ -114,10 +118,12 @@ copy_to_user(void __user *to, const void *from, unsigned n) do { \ long __d0; \ __asm__ __volatile__( \ + ASM_STAC"\n" \ "0: rep; stosl\n" \ " movl %2,%0\n" \ "1: rep; stosb\n" \ "2:\n" \ + ASM_CLAC"\n" \ ".section .fixup,\"ax\"\n" \ "3: lea 0(%2,%0,4),%0\n" \ " jmp 2b\n" \ diff --git a/xen/arch/x86/x86_64/compat/entry.S b/xen/arch/x86/x86_64/compat/entry.S index ac594c9..298c1a9 100644 --- a/xen/arch/x86/x86_64/compat/entry.S +++ b/xen/arch/x86/x86_64/compat/entry.S @@ -266,6 +266,7 @@ ENTRY(compat_int80_direct_trap) /* On return only %rbx and %rdx are guaranteed non-clobbered. */ compat_create_bounce_frame: ASSERT_INTERRUPTS_ENABLED + ASM_STAC mov %fs,%edi testb $2,UREGS_cs+8(%rsp) jz 1f @@ -337,6 +338,7 @@ __UNLIKELY_END(compat_bounce_null_selector) movl %eax,UREGS_cs+8(%rsp) movl TRAPBOUNCE_eip(%rdx),%eax movl %eax,UREGS_rip+8(%rsp) + ASM_CLAC ret .section .fixup,"ax" .Lfx13: diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S index 5f46803..c30d360 100644 --- a/xen/arch/x86/x86_64/entry.S +++ b/xen/arch/x86/x86_64/entry.S @@ -379,6 +379,7 @@ __UNLIKELY_END(create_bounce_frame_bad_sp) movb TRAPBOUNCE_flags(%rdx),%cl subq $40,%rsi movq UREGS_ss+8(%rsp),%rax + ASM_STAC .Lft2: movq %rax,32(%rsi) # SS movq UREGS_rsp+8(%rsp),%rax .Lft3: movq %rax,24(%rsi) # RSP @@ -439,6 +440,7 @@ UNLIKELY_START(z, create_bounce_frame_bad_bounce_ip) jmp asm_domain_crash_synchronous /* Does not return */ __UNLIKELY_END(create_bounce_frame_bad_bounce_ip) movq %rax,UREGS_rip+8(%rsp) + ASM_CLAC ret _ASM_EXTABLE(.Lft2, dom_crash_sync_extable) _ASM_EXTABLE(.Lft3, dom_crash_sync_extable) diff --git a/xen/include/asm-x86/uaccess.h b/xen/include/asm-x86/uaccess.h index 88b4ba2..ce1af4a 100644 --- a/xen/include/asm-x86/uaccess.h +++ b/xen/include/asm-x86/uaccess.h @@ -147,8 +147,10 @@ struct __large_struct { unsigned long buf[100]; }; */ #define __put_user_asm(x, addr, err, itype, rtype, ltype, errret) \ __asm__ __volatile__( \ + ASM_STAC"\n" \ "1: mov"itype" %"rtype"1,%2\n" \ "2:\n" \ + ASM_CLAC"\n" \ ".section .fixup,\"ax\"\n" \ "3: mov %3,%0\n" \ " jmp 2b\n" \ @@ -159,8 +161,10 @@ struct __large_struct { unsigned long buf[100]; }; #define __get_user_asm(x, addr, err, itype, rtype, ltype, errret) \ __asm__ __volatile__( \ + ASM_STAC"\n" \ "1: mov"itype" %2,%"rtype"1\n" \ "2:\n" \ + ASM_CLAC"\n" \ ".section .fixup,\"ax\"\n" \ "3: mov %3,%0\n" \ " xor"itype" %"rtype"1,%"rtype"1\n" \ diff --git a/xen/include/asm-x86/x86_64/system.h b/xen/include/asm-x86/x86_64/system.h index 20f038b..b8394b9 100644 --- a/xen/include/asm-x86/x86_64/system.h +++ b/xen/include/asm-x86/x86_64/system.h @@ -13,8 +13,10 @@ */ #define __cmpxchg_user(_p,_o,_n,_isuff,_oppre,_regtype) \ asm volatile ( \ + ASM_STAC"\n" \ "1: lock; cmpxchg"_isuff" %"_oppre"2,%3\n" \ "2:\n" \ + ASM_CLAC"\n" \ ".section .fixup,\"ax\"\n" \ "3: movl $1,%1\n" \ " jmp 2b\n" \ -- 1.8.3.1 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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