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x86/vdso: Define BUILD_VDSO while building and emit .eh_frame in asm 

For the vDSO, user code wants runtime unwind info.  Make sure
that, if we use .cfi directives, we generate it.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/16e29ad8855e6508197000d8c41f56adb00d7580.1444091584.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2015-10-05 17:47:58 -07:00 committed by Ingo Molnar
parent 7b956f035a
commit f24f910884
2 changed files with 12 additions and 5 deletions
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4
arch/x86/entry/vdso/Makefile
View File

@ -67,7 +67,7 @@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE
CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
$(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
-fno-omit-frame-pointer -foptimize-sibling-calls \
-DDISABLE_BRANCH_PROFILING
-DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
$(vobjs): KBUILD_CFLAGS += $(CFL)
@ -131,7 +131,7 @@ targets += vdso32/vdso32.lds
targets += vdso32/note.o vdso32/vclock_gettime.o vdso32/system_call.o
targets += vdso32/vclock_gettime.o
KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS))
KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS)) -DBUILD_VDSO
$(obj)/vdso32.so.dbg: KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)
$(obj)/vdso32.so.dbg: asflags-$(CONFIG_X86_64) += -m32

13
arch/x86/include/asm/dwarf2.h
View File

@ -36,15 +36,22 @@
#endif
#if defined(CONFIG_AS_CFI_SECTIONS) && defined(__ASSEMBLY__)
#ifndef BUILD_VDSO
/*
* Emit CFI data in .debug_frame sections, not .eh_frame sections.
* The latter we currently just discard since we don't do DWARF
* unwinding at runtime. So only the offline DWARF information is
* useful to anyone. Note we should not use this directive if this
* file is used in the vDSO assembly, or if vmlinux.lds.S gets
* changed so it doesn't discard .eh_frame.
* useful to anyone. Note we should not use this directive if
* vmlinux.lds.S gets changed so it doesn't discard .eh_frame.
*/
.cfi_sections .debug_frame
#else
/*
* For the vDSO, emit both runtime unwind information and debug
* symbols for the .dbg file.
*/
.cfi_sections .eh_frame, .debug_frame
#endif
#endif
#else