[PATCH V6 38/49] x86/debug, mce: Use C entry code

[Lai Jiangshan]

From: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxxx>
---
 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