On February 10, 2026 8:46:33 AM PST, Jens Remus <[email protected]> wrote: >On 2/6/2026 8:36 PM, Jens Remus wrote: >> From: Josh Poimboeuf <[email protected]> >> >> Enable sframe generation in the VDSO library so kernel and user space >> can unwind through it. >> >> SFrame isn't supported for x32 or x86-32. Discard .sframe sections for >> those VDSOs. >> >> [ Jens Remus: Add support for SFrame V3. Prevent GNU_SFRAME program >> table entry to empty .sframe section. ] >> >> Signed-off-by: Josh Poimboeuf <[email protected]> >> Signed-off-by: Steven Rostedt (Google) <[email protected]> >> Signed-off-by: Jens Remus <[email protected]> > >> diff --git a/arch/Kconfig b/arch/Kconfig > >> @@ -479,6 +479,13 @@ config HAVE_HARDLOCKUP_DETECTOR_ARCH >> It uses the same command line parameters, and sysctl interface, >> as the generic hardlockup detectors. >> >> +config AS_SFRAME >> + bool >> + >> +config AS_SFRAME3 >> + def_bool $(as-instr,.cfi_startproc\n.cfi_endproc,-Wa$(comma)--gsframe-3) > >Above tests whether the assembler supports --gsframe-3 to generate >.sframe in SFrame V3 format. GNU assembler only supports to generate >SFrame for x86-64. If the assembler is built for i386 (x86-32) the test >will fail unless option --64 is specified. I wonder whether that could >happen in (the rather hypothetical?) case, when the kernel is cross built >for x86-64 on i386? Should this therefore be changed to the following? > >config AS_SFRAME_64 > def_bool $(as-instr,.cfi_startproc\n.cfi_endproc,$(m64-flag) > -Wa$(comma)--gsframe) > >An alternative would be to enable as-instr64 to accept an optional flag >operand, similar to as-instr, and use as-instr64 instead of as-instr. > >Or is this not required, as in a cross build for 64-bit on a 32-bit >platform (or inverse) a respective cross toolchain is a prerequisite and >the m64-flag (or m32-flag) is not used? > >I tried to simulate this using docker and an i386 image and then using >the i386 tool in the container to switch "uname -m" to "i686". But both >of my following attempts to build for x86-64 on i386 fail with fixdep >not found: > >$ docker run -it --rm -v "$HOME/linux:$HOME/linux" --platform i386 >public.ecr.aws/docker/library/debian:13.3 ># sed -i -s 's/^Types: deb/& deb-src/' /etc/apt/sources.list.d/debian.sources ># apt update ># apt -y build-dep linux > ># make mrproper ># i386 make ARCH=x86_64 defconfig ># i386 make ARCH=x86_64 arch/x86/entry/vdso/ > ># make mrproper ># apt -y install gcc-x86-64-linux-gnu ># i386 make ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu- defconfig ># i386 make ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu- arch/x86/entry/vdso/ > >> + select AS_SFRAME >> + >> config UNWIND_USER >> bool > >> diff --git a/arch/x86/entry/vdso/vdso64/Makefile >> b/arch/x86/entry/vdso/vdso64/Makefile > >> @@ -14,6 +14,7 @@ vobjs-$(CONFIG_X86_SGX) += vsgx.o >> >> # Compilation flags >> flags-y := -DBUILD_VDSO64 -m64 -mcmodel=small >> +flags-$(CONFIG_AS_SFRAME3) += -Wa,--gsframe-3 > >flags-$(CONFIG_AS_SFRAME3_64) += -Wa,--gsframe-3 > >> >> # The location of this include matters! >> include $(src)/../common/Makefile.include >Thanks and regards, >Jens
I think we can worry about that later.
