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Subject[PATCH V6 38/49] x86/debug, mce: Use C entry code
Date
From: Lai Jiangshan <laijs@linux.alibaba.com>

Use DEFINE_IDTENTRY_IST_ENTRY to emit C entry function in C files and
use the function directly in entry_64.S.

It also removes stack-protector from C files because the C entry code
can NOT use percpu register until GSBASE is properly switched.
And stack-protector depends on the percpu register to work.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/entry/entry_64.S | 10 +---------
arch/x86/include/asm/idtentry.h | 1 +
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/cpu/mce/Makefile | 3 +++
4 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index bd5e005316a3..ac05cbf894f5 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -465,16 +465,8 @@ SYM_CODE_START(\asmsym)
testb $3, CS(%rsp)
jnz .Lfrom_usermode_switch_stack_\@

- /* paranoid_entry returns GS information for paranoid_exit in EBX. */
- call paranoid_entry
-
- UNWIND_HINT_REGS
-
movq %rsp, %rdi /* pt_regs pointer */
-
- call \cfunc
-
- call paranoid_exit
+ call ist_\cfunc
jmp restore_regs_and_return_to_kernel

/* Switch to the regular task stack and use the noist entry point */
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 7b17ffa43e10..f274e4e2ca17 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -358,6 +358,7 @@ __visible __entry_text void ist_##func(struct pt_regs *regs) \
* Maps to DEFINE_IDTENTRY_RAW
*/
#define DEFINE_IDTENTRY_IST(func) \
+ DEFINE_IDTENTRY_IST_ENTRY(func) \
DEFINE_IDTENTRY_RAW(func)

/**
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 2ff3e600f426..8ac45801ba8b 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -50,6 +50,7 @@ KCOV_INSTRUMENT := n

CFLAGS_head$(BITS).o += -fno-stack-protector
CFLAGS_cc_platform.o += -fno-stack-protector
+CFLAGS_traps.o += -fno-stack-protector

CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace

diff --git a/arch/x86/kernel/cpu/mce/Makefile b/arch/x86/kernel/cpu/mce/Makefile
index 015856abdbb1..555963416ec3 100644
--- a/arch/x86/kernel/cpu/mce/Makefile
+++ b/arch/x86/kernel/cpu/mce/Makefile
@@ -1,4 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
+
+CFLAGS_core.o += -fno-stack-protector
+
obj-y = core.o severity.o genpool.o

obj-$(CONFIG_X86_ANCIENT_MCE) += winchip.o p5.o
--
2.19.1.6.gb485710b
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