[Xen-devel] [PATCH v2 2/7] Clear AC bit in RFLAGS to protect Xen itself by SMAP

[Feng Wu <feng.wu@xxxxxxxxx>]

Clear AC bit in RFLAGS at the beginning of exception, interrupt, hypercall,
so Xen itself can be protected by SMAP mechanism.

Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
---
 xen/arch/x86/x86_64/compat/entry.S     |  1 +
 xen/arch/x86/x86_64/entry.S            | 26 ++++++++++++++++++++++++++
 xen/include/asm-x86/x86_64/asm_defns.h |  1 +
 3 files changed, 28 insertions(+)

diff --git a/xen/arch/x86/x86_64/compat/entry.S 
b/xen/arch/x86/x86_64/compat/entry.S
index 32b3bcc..ac594c9 100644
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -13,6 +13,7 @@
 #include <irq_vectors.h>
 
 ENTRY(compat_hypercall)
+        ASM_CLAC
         pushq $0
         SAVE_VOLATILE type=TRAP_syscall compat=1
 
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 3ea4683..d294064 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -120,6 +120,7 @@ restore_all_xen:
  * the space left by the trampoline.
  */
 ENTRY(syscall_enter)
+        ASM_CLAC
         sti
         movl  $FLAT_KERNEL_SS,24(%rsp)
         pushq %rcx
@@ -268,6 +269,7 @@ bad_hypercall:
         jmp  test_all_events
 
 ENTRY(sysenter_entry)
+        ASM_CLAC
         sti
         pushq $FLAT_USER_SS
         pushq $0
@@ -309,6 +311,7 @@ UNLIKELY_END(sysenter_gpf)
         jmp   .Lbounce_exception
 
 ENTRY(int80_direct_trap)
+        ASM_CLAC
         pushq $0
         SAVE_VOLATILE 0x80
 
@@ -476,6 +479,7 @@ ENTRY(ret_from_intr)
         jmp   compat_test_all_events
 
 ENTRY(page_fault)
+        ASM_CLAC
         movl  $TRAP_page_fault,4(%rsp)
 /* No special register assumptions. */
 GLOBAL(handle_exception)
@@ -532,81 +536,98 @@ FATAL_exception_with_ints_disabled:
         ud2
 
 ENTRY(divide_error)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_divide_error,4(%rsp)
         jmp   handle_exception
 
 ENTRY(coprocessor_error)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_copro_error,4(%rsp)
         jmp   handle_exception
 
 ENTRY(simd_coprocessor_error)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_simd_error,4(%rsp)
         jmp   handle_exception
 
 ENTRY(device_not_available)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_no_device,4(%rsp)
         jmp   handle_exception
 
 ENTRY(debug)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_debug,4(%rsp)
         jmp   handle_exception
 
 ENTRY(int3)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_int3,4(%rsp)
         jmp   handle_exception
 
 ENTRY(overflow)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_overflow,4(%rsp)
         jmp   handle_exception
 
 ENTRY(bounds)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_bounds,4(%rsp)
         jmp   handle_exception
 
 ENTRY(invalid_op)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_invalid_op,4(%rsp)
         jmp   handle_exception
 
 ENTRY(coprocessor_segment_overrun)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_copro_seg,4(%rsp)
         jmp   handle_exception
 
 ENTRY(invalid_TSS)
+        ASM_CLAC
         movl  $TRAP_invalid_tss,4(%rsp)
         jmp   handle_exception
 
 ENTRY(segment_not_present)
+        ASM_CLAC
         movl  $TRAP_no_segment,4(%rsp)
         jmp   handle_exception
 
 ENTRY(stack_segment)
+        ASM_CLAC
         movl  $TRAP_stack_error,4(%rsp)
         jmp   handle_exception
 
 ENTRY(general_protection)
+        ASM_CLAC
         movl  $TRAP_gp_fault,4(%rsp)
         jmp   handle_exception
 
 ENTRY(alignment_check)
+        ASM_CLAC
         movl  $TRAP_alignment_check,4(%rsp)
         jmp   handle_exception
 
 ENTRY(spurious_interrupt_bug)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_spurious_int,4(%rsp)
         jmp   handle_exception
 
 ENTRY(double_fault)
+        ASM_CLAC
         movl  $TRAP_double_fault,4(%rsp)
         SAVE_ALL
         movq  %rsp,%rdi
@@ -615,6 +636,7 @@ ENTRY(double_fault)
 
         .pushsection .init.text, "ax", @progbits
 ENTRY(early_page_fault)
+        ASM_CLAC
         SAVE_ALL
         movq  %rsp,%rdi
         call  do_early_page_fault
@@ -622,6 +644,7 @@ ENTRY(early_page_fault)
         .popsection
 
 ENTRY(nmi)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_nmi,4(%rsp)
 handle_ist_exception:
@@ -659,6 +682,7 @@ handle_ist_exception:
         jmp   compat_restore_all_guest
 
 ENTRY(nmi_crash)
+        ASM_CLAC
         pushq $0
         movl $TRAP_nmi,4(%rsp)
         SAVE_ALL
@@ -667,6 +691,7 @@ ENTRY(nmi_crash)
         ud2
 
 ENTRY(machine_check)
+        ASM_CLAC
         pushq $0
         movl  $TRAP_machine_check,4(%rsp)
         jmp   handle_ist_exception
@@ -689,6 +714,7 @@ ENTRY(enable_nmis)
 
 /* No op trap handler.  Required for kexec crash path. */
 GLOBAL(trap_nop)
+        ASM_CLAC
         iretq
 
 
diff --git a/xen/include/asm-x86/x86_64/asm_defns.h 
b/xen/include/asm-x86/x86_64/asm_defns.h
index bf63ac1..69f76b2 100644
--- a/xen/include/asm-x86/x86_64/asm_defns.h
+++ b/xen/include/asm-x86/x86_64/asm_defns.h
@@ -212,6 +212,7 @@
 __asm__(                                        \
     "\n" __ALIGN_STR"\n"                        \
     "common_interrupt:\n\t"                     \
+    ASM_CLAC(%)"\n\t"                           \
     STR(SAVE_ALL) "\n\t"                        \
     "movq %rsp,%rdi\n\t"                        \
     "callq " STR(do_IRQ) "\n\t"                 \
-- 
1.8.3.1


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