| Message ID | c93fbd53f01c2c86f747af27040ac11f16dee032.1737511963.git.jpoimboe@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | unwind, perf: sframe user space unwinding | expand |
On 22.01.2025 03:31, Josh Poimboeuf wrote: > Enable sframe generation in the VDSO library so kernel and user space > can unwind through it. > > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> ... > diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h > index b195b3c8677e..1c354f648505 100644 > --- a/arch/x86/include/asm/dwarf2.h > +++ b/arch/x86/include/asm/dwarf2.h > @@ -12,8 +12,11 @@ > * For the vDSO, emit both runtime unwind information and debug > * symbols for the .dbg file. > */ > - Nit: Deleted blank line you introduced in "[PATCH v4 05/39] x86/asm: Avoid emitting DWARF CFI for non-VDSO". > +#ifdef __x86_64__ #if defined(__x86_64__) && defined(CONFIG_AS_SFRAME) AFAIK the kernel has a minimum binutils requirement of 2.25 [1] and assembler option "--gsframe" as well as directive ".cfi_sections .sframe" were introduced with 2.40. > + .cfi_sections .eh_frame, .debug_frame, .sframe > +#else > .cfi_sections .eh_frame, .debug_frame > +#endif > > #define CFI_STARTPROC .cfi_startproc > #define CFI_ENDPROC .cfi_endproc [1]: https://docs.kernel.org/process/changes.html Regards, Jens
On 22.01.2025 03:31, Josh Poimboeuf wrote: > Enable sframe generation in the VDSO library so kernel and user space > can unwind through it. > > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> > diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile > @@ -47,13 +47,17 @@ quiet_cmd_vdso2c = VDSO2C $@ > $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE > $(call if_changed,vdso2c) > > +#ifdef CONFIG_AS_SFRAME > +SFRAME_CFLAGS := -Wa$(comma)-gsframe > +#endif > + You probably erroneously mixed up C preprocessor and Makefile syntax? :-) ifeq ($(CONFIG_AS_SFRAME),y) SFRAME_CFLAGS := -Wa,--gsframe endif $(comma) does not appear to be required in this context. Regards, Jens
On Fri, Jan 24, 2025 at 05:00:27PM +0100, Jens Remus wrote: > On 22.01.2025 03:31, Josh Poimboeuf wrote: > > diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h > > index b195b3c8677e..1c354f648505 100644 > > --- a/arch/x86/include/asm/dwarf2.h > > +++ b/arch/x86/include/asm/dwarf2.h > > @@ -12,8 +12,11 @@ > > * For the vDSO, emit both runtime unwind information and debug > > * symbols for the .dbg file. > > */ > > - > > Nit: Deleted blank line you introduced in "[PATCH v4 05/39] x86/asm: > Avoid emitting DWARF CFI for non-VDSO". Indeed. > > +#ifdef __x86_64__ > > #if defined(__x86_64__) && defined(CONFIG_AS_SFRAME) > > AFAIK the kernel has a minimum binutils requirement of 2.25 [1] > and assembler option "--gsframe" as well as directive > ".cfi_sections .sframe" were introduced with 2.40. True, I'll change it to just '#ifdef CONFIG_AS_SFRAME' since that's what really matters (and 32-bit doesn't support it anyway). > > + .cfi_sections .eh_frame, .debug_frame, .sframe > > +#else > > .cfi_sections .eh_frame, .debug_frame > > +#endif > > #define CFI_STARTPROC .cfi_startproc > > #define CFI_ENDPROC .cfi_endproc
On Fri, Jan 24, 2025 at 08:43:35AM -0800, Josh Poimboeuf wrote: > On Fri, Jan 24, 2025 at 05:00:27PM +0100, Jens Remus wrote: > > On 22.01.2025 03:31, Josh Poimboeuf wrote: > > > +#ifdef __x86_64__ > > > > #if defined(__x86_64__) && defined(CONFIG_AS_SFRAME) > > > > AFAIK the kernel has a minimum binutils requirement of 2.25 [1] > > and assembler option "--gsframe" as well as directive > > ".cfi_sections .sframe" were introduced with 2.40. > > True, I'll change it to just '#ifdef CONFIG_AS_SFRAME' since that's what > really matters (and 32-bit doesn't support it anyway). Actually, just CONFIG_AS_CFAME didn't work as 64-bit still compiles some 32-bit asm files. I'll go with your suggestion.
On Fri, Jan 24, 2025 at 05:30:36PM +0100, Jens Remus wrote: > On 22.01.2025 03:31, Josh Poimboeuf wrote: > > Enable sframe generation in the VDSO library so kernel and user space > > can unwind through it. > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> > > > diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile > > > @@ -47,13 +47,17 @@ quiet_cmd_vdso2c = VDSO2C $@ > > $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE > > $(call if_changed,vdso2c) > > +#ifdef CONFIG_AS_SFRAME > > +SFRAME_CFLAGS := -Wa$(comma)-gsframe > > +#endif > > + > > You probably erroneously mixed up C preprocessor and Makefile syntax? :-) > > ifeq ($(CONFIG_AS_SFRAME),y) > SFRAME_CFLAGS := -Wa,--gsframe > endif > > $(comma) does not appear to be required in this context. Yeah, before it was in a Makefile macro which needed the $(comma) to distinguish it from the macro arguments.
diff --git a/arch/Kconfig b/arch/Kconfig index 6682b2a53e34..65228c78fef0 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -435,6 +435,9 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH It uses the same command line parameters, and sysctl interface, as the generic hardlockup detectors. +config AS_SFRAME + def_bool $(as-instr,.cfi_sections .sframe\n.cfi_startproc\n.cfi_endproc) + config HAVE_PERF_REGS bool help diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index c9216ac4fb1e..478de89029d1 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -47,13 +47,17 @@ quiet_cmd_vdso2c = VDSO2C $@ $(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE $(call if_changed,vdso2c) +#ifdef CONFIG_AS_SFRAME +SFRAME_CFLAGS := -Wa$(comma)-gsframe +#endif + # # Don't omit frame pointers for ease of userspace debugging, but do # optimize sibling calls. # CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \ $(filter -g%,$(KBUILD_CFLAGS)) -fno-stack-protector \ - -fno-omit-frame-pointer -foptimize-sibling-calls \ + -fno-omit-frame-pointer $(SFRAME_CFLAGS) -foptimize-sibling-calls \ -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO ifdef CONFIG_MITIGATION_RETPOLINE @@ -63,7 +67,7 @@ endif endif $(vobjs): KBUILD_CFLAGS := $(filter-out $(PADDING_CFLAGS) $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) -$(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO +$(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO $(SFRAME_CFLAGS) # # vDSO code runs in userspace and -pg doesn't help with profiling anyway. @@ -104,7 +108,7 @@ $(obj)/%-x32.o: $(obj)/%.o FORCE targets += vdsox32.lds $(vobjx32s-y) -$(obj)/%.so: OBJCOPYFLAGS := -S --remove-section __ex_table +$(obj)/%.so: OBJCOPYFLAGS := -g --remove-section __ex_table $(obj)/%.so: $(obj)/%.so.dbg FORCE $(call if_changed,objcopy) diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S index 506c9800a5aa..4dcde4747b07 100644 --- a/arch/x86/entry/vdso/vdso-layout.lds.S +++ b/arch/x86/entry/vdso/vdso-layout.lds.S @@ -63,6 +63,7 @@ SECTIONS .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr .eh_frame : { KEEP (*(.eh_frame)) } :text + .sframe : { *(.sframe) } :text :sframe /* * Text is well-separated from actual data: there's plenty of @@ -91,6 +92,7 @@ SECTIONS * Very old versions of ld do not recognize this name token; use the constant. */ #define PT_GNU_EH_FRAME 0x6474e550 +#define PT_GNU_SFRAME 0x6474e554 /* * We must supply the ELF program headers explicitly to get just one @@ -102,4 +104,5 @@ PHDRS dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ note PT_NOTE FLAGS(4); /* PF_R */ eh_frame_hdr PT_GNU_EH_FRAME; + sframe PT_GNU_SFRAME; } diff --git a/arch/x86/include/asm/dwarf2.h b/arch/x86/include/asm/dwarf2.h index b195b3c8677e..1c354f648505 100644 --- a/arch/x86/include/asm/dwarf2.h +++ b/arch/x86/include/asm/dwarf2.h @@ -12,8 +12,11 @@ * For the vDSO, emit both runtime unwind information and debug * symbols for the .dbg file. */ - +#ifdef __x86_64__ + .cfi_sections .eh_frame, .debug_frame, .sframe +#else .cfi_sections .eh_frame, .debug_frame +#endif #define CFI_STARTPROC .cfi_startproc #define CFI_ENDPROC .cfi_endproc
Enable sframe generation in the VDSO library so kernel and user space can unwind through it. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> --- arch/Kconfig | 3 +++ arch/x86/entry/vdso/Makefile | 10 +++++++--- arch/x86/entry/vdso/vdso-layout.lds.S | 3 +++ arch/x86/include/asm/dwarf2.h | 5 ++++- 4 files changed, 17 insertions(+), 4 deletions(-)