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Subject[PATCH 10/31] x86/entry/32: Introduce SAVE_ALL_NMI and RESTORE_ALL_NMI
Date
From: Joerg Roedel <jroedel@suse.de>

These macros will be used in the NMI handler code and
replace plain SAVE_ALL and RESTORE_REGS there. We will add
the NMI-specific CR3-switch to these macros later.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/entry/entry_32.S | 23 +++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index ba3d8c2..be1d814 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -167,6 +167,9 @@

.endm

+.macro SAVE_ALL_NMI
+ SAVE_ALL
+.endm
/*
* This is a sneaky trick to help the unwinder find pt_regs on the stack. The
* frame pointer is replaced with an encoded pointer to pt_regs. The encoding
@@ -224,6 +227,18 @@
RESTORE_SKIP_SEGMENTS \pop
.endm

+.macro RESTORE_ALL_NMI pop=0
+ /*
+ * Restore segments - might cause exceptions when loading
+ * user-space segments
+ */
+ RESTORE_SEGMENTS
+
+ /* Restore integer registers and unwind stack to iret frame */
+ RESTORE_INT_REGS
+ RESTORE_SKIP_SEGMENTS \pop
+.endm
+
.macro CHECK_AND_APPLY_ESPFIX
#ifdef CONFIG_X86_ESPFIX32
#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8)
@@ -1127,7 +1142,7 @@ ENTRY(nmi)
#endif

pushl %eax # pt_regs->orig_ax
- SAVE_ALL
+ SAVE_ALL_NMI
ENCODE_FRAME_POINTER
xorl %edx, %edx # zero error code
movl %esp, %eax # pt_regs pointer
@@ -1155,7 +1170,7 @@ ENTRY(nmi)

.Lnmi_return:
CHECK_AND_APPLY_ESPFIX
- RESTORE_REGS 4
+ RESTORE_ALL_NMI pop=4
jmp .Lirq_return

#ifdef CONFIG_X86_ESPFIX32
@@ -1171,12 +1186,12 @@ ENTRY(nmi)
pushl 16(%esp)
.endr
pushl %eax
- SAVE_ALL
+ SAVE_ALL_NMI
ENCODE_FRAME_POINTER
FIXUP_ESPFIX_STACK # %eax == %esp
xorl %edx, %edx # zero error code
call do_nmi
- RESTORE_REGS
+ RESTORE_ALL_NMI
lss 12+4(%esp), %esp # back to espfix stack
jmp .Lirq_return
#endif
--
2.7.4
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