x86, msr: CFI annotations, cleanups for msr-reg.S

Add CFI annotations for native_{rd,wr}msr_safe_regs().
Simplify the 64-bit implementation: we don't allow the upper half
registers to be set, and so we can use them to carry state across the
operation.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <petkovbb@gmail.com>
LKML-Reference: <1251705011-18636-1-git-send-email-petkovbb@gmail.com>

1 files changed, 42 insertions, 38 deletions

diff --git a/arch/x86/lib/msr-reg.S b/arch/x86/lib/msr-reg.S
index 51f1bb3f8c79..9e8cdcf5d73c 100644
--- a/arch/x86/lib/msr-reg.S
+++ b/arch/x86/lib/msr-reg.S
@@ -1,5 +1,6 @@
 #include <linux/linkage.h>
 #include <linux/errno.h>
+#include <asm/dwarf2.h>
 #include <asm/asm.h>
 #include <asm/msr.h>
 
@@ -12,10 +13,11 @@
  */
 .macro op_safe_regs op:req
 ENTRY(native_\op\()_safe_regs)
-        push    %rbx
-        push    %rbp
-        push    $0              /* Return value */
-        push    %rdi
+        CFI_STARTPROC
+        pushq_cfi %rbx
+        pushq_cfi %rbp
+        movq    %rdi, %r10      /* Save pointer */
+        xorl    %r11d, %r11d    /* Return value */
         movl    (%rdi), %eax
         movl    4(%rdi), %ecx
         movl    8(%rdi), %edx
@@ -23,27 +25,26 @@ ENTRY(native_\op\()_safe_regs)
         movl    20(%rdi), %ebp
         movl    24(%rdi), %esi
         movl    28(%rdi), %edi
+        CFI_REMEMBER_STATE
 1:      \op
-2:      movl    %edi, %r10d
-        pop     %rdi
-        movl    %eax, (%rdi)
-        movl    %ecx, 4(%rdi)
-        movl    %edx, 8(%rdi)
-        movl    %ebx, 12(%rdi)
-        movl    %ebp, 20(%rdi)
-        movl    %esi, 24(%rdi)
-        movl    %r10d, 28(%rdi)
-        pop     %rax
-        pop     %rbp
-        pop     %rbx
+2:      movl    %eax, (%r10)
+        movl    %r11d, %eax     /* Return value */
+        movl    %ecx, 4(%r10)
+        movl    %edx, 8(%r10)
+        movl    %ebx, 12(%r10)
+        movl    %ebp, 20(%r10)
+        movl    %esi, 24(%r10)
+        movl    %edi, 28(%r10)
+        popq_cfi %rbp
+        popq_cfi %rbx
         ret
 3:
-        movq    $-EIO, 8(%rsp)
+        CFI_RESTORE_STATE
+        movl    $-EIO, %r11d
         jmp     2b
-        .section __ex_table,"ax"
-        .balign 4
-        .quad   1b, 3b
-        .previous
+
+        _ASM_EXTABLE(1b, 3b)
+        CFI_ENDPROC
 ENDPROC(native_\op\()_safe_regs)
 .endm
 
@@ -51,12 +52,13 @@ ENDPROC(native_\op\()_safe_regs)
 
 .macro op_safe_regs op:req
 ENTRY(native_\op\()_safe_regs)
-        push    %ebx
-        push    %ebp
-        push    %esi
-        push    %edi
-        push    $0              /* Return value */
-        push    %eax
+        CFI_STARTPROC
+        pushl_cfi %ebx
+        pushl_cfi %ebp
+        pushl_cfi %esi
+        pushl_cfi %edi
+        pushl_cfi $0              /* Return value */
+        pushl_cfi %eax
         movl    4(%eax), %ecx
         movl    8(%eax), %edx
         movl    12(%eax), %ebx
@@ -64,30 +66,32 @@ ENTRY(native_\op\()_safe_regs)
         movl    24(%eax), %esi
         movl    28(%eax), %edi
         movl    (%eax), %eax
+        CFI_REMEMBER_STATE
 1:      \op
-2:      push    %eax
+2:      pushl_cfi %eax
         movl    4(%esp), %eax
-        pop     (%eax)
+        popl_cfi (%eax)
         addl    $4, %esp
+        CFI_ADJUST_CFA_OFFSET -4
         movl    %ecx, 4(%eax)
         movl    %edx, 8(%eax)
         movl    %ebx, 12(%eax)
         movl    %ebp, 20(%eax)
         movl    %esi, 24(%eax)
         movl    %edi, 28(%eax)
-        pop     %eax
-        pop     %edi
-        pop     %esi
-        pop     %ebp
-        pop     %ebx
+        popl_cfi %eax
+        popl_cfi %edi
+        popl_cfi %esi
+        popl_cfi %ebp
+        popl_cfi %ebx
         ret
 3:
+        CFI_RESTORE_STATE
         movl    $-EIO, 4(%esp)
         jmp     2b
-        .section __ex_table,"ax"
-        .balign 4
-        .long   1b, 3b
-        .previous
+
+        _ASM_EXTABLE(1b, 3b)
+        CFI_ENDPROC
 ENDPROC(native_\op\()_safe_regs)
 .endm