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SubjectRe: [RFC PATCH 2/3] objtool: Enable and implement 'mcount' subcommand
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Le 18/03/2022 à 11:51, Sathvika Vasireddy a écrit :
> This patch adds 'mcount' as a subcommand to objtool, and enables
> the same for x86. objtool is built if CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
> is selected. Additionally, architectures can select HAVE_NOP_MCOUNT
> if they choose to nop out mcount call sites. If that config option is
> selected, then --mnop is passed as an option to 'objtool mcount'
>
> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
> ---
> Makefile | 6 ++
> arch/x86/Kconfig | 3 +-
> scripts/Makefile.build | 12 +++
> tools/objtool/Build | 2 +
> tools/objtool/Makefile | 4 +-
> tools/objtool/builtin-mcount.c | 74 +++++++++++++
> tools/objtool/include/objtool/builtin.h | 4 +-
> tools/objtool/include/objtool/objtool.h | 1 +
> tools/objtool/mcount.c | 138 ++++++++++++++++++++++++
> tools/objtool/objtool.c | 1 +
> tools/objtool/weak.c | 5 +
> 11 files changed, 247 insertions(+), 3 deletions(-)
> create mode 100644 tools/objtool/builtin-mcount.c
> create mode 100644 tools/objtool/mcount.c
>
> diff --git a/Makefile b/Makefile
> index 55a30ca69350..316f7d08b30a 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -846,7 +846,9 @@ ifdef CONFIG_FTRACE_MCOUNT_USE_CC
> endif
> endif
> ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
> + ifdef CONFIG_HAVE_NOP_MCOUNT
> CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
> + endif
> endif
> ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
> ifdef CONFIG_HAVE_C_RECORDMCOUNT
> @@ -1303,6 +1305,10 @@ ifdef CONFIG_STACK_VALIDATION
> prepare: tools/objtool
> endif
>
> +ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
> +prepare: tools/objtool
> +endif

I don't think that will work for powerpc.

See arch/powerpc/Makefile

powerpc builds the VDSO under prepare: , and powerpc has
CONFIG_HAVE_GENERIC_VDSO so there are some C files in that step that
seem to use objtool, allthough that looks odd to me. Must be something
to fix somewhere.

powerpc64-linux-gcc
-Wp,-MMD,arch/powerpc/kernel/vdso/.vgettimeofday-64.o.d -nostdinc
-I./arch/powerpc/include -I./arch/powerpc/include/generated -I./include
-I./arch/powerpc/include/uapi -I./arch/powerpc/include/generated/uapi
-I./include/uapi -I./include/generated/uapi -include
./include/linux/compiler-version.h -include ./include/linux/kconfig.h
-include ./include/linux/compiler_types.h -D__KERNEL__ -I ./arch/powerpc
-DHAVE_AS_ATHIGH=1 -fmacro-prefix-map=./= -Wall -Wundef
-Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing
-fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration
-Werror=implicit-int -Werror=return-type -Wno-format-security -std=gnu89
-mbig-endian -m64 -msoft-float -pipe -mtraceback=no -mabi=elfv1
-mcall-aixdesc -mcmodel=medium -mno-pointers-to-nested-functions
-mtune=power7 -mcpu=power5 -mno-altivec -mno-vsx
-fno-asynchronous-unwind-tables -mno-string -Wa,-maltivec -Wa,-mpower4
-Wa,-many -mabi=elfv1 -mcall-aixdesc -mbig-endian
-mstack-protector-guard=tls -mstack-protector-guard-reg=r13
-fno-delete-null-pointer-checks -Wno-frame-address
-Wno-format-truncation -Wno-format-overflow
-Wno-address-of-packed-member -O2 -fno-allow-store-data-races
-Wframe-larger-than=2048 -fstack-protector-strong
-Wimplicit-fallthrough=5 -Wno-main -Wno-unused-but-set-variable
-Wno-unused-const-variable -fno-stack-clash-protection
-Wdeclaration-after-statement -Wvla -Wno-pointer-sign
-Wcast-function-type -Wno-stringop-truncation -Wno-zero-length-bounds
-Wno-array-bounds -Wno-stringop-overflow -Wno-restrict
-Wno-maybe-uninitialized -Wno-alloc-size-larger-than
-fno-strict-overflow -fno-stack-check -fconserve-stack -Werror=date-time
-Werror=incompatible-pointer-types -Werror=designated-init
-Wno-packed-not-aligned -mstack-protector-guard-offset=3200 -shared
-fno-common -fno-builtin -nostdlib -Wl,--hash-style=both -include
/home/chleroy/linux-powerpc/lib/vdso/gettimeofday.c -fno-stack-protector
-DDISABLE_BRANCH_PROFILING -ffreestanding -fasynchronous-unwind-tables
-ffixed-r30
-DKBUILD_MODFILE='"arch/powerpc/kernel/vdso/vgettimeofday-64"'
-DKBUILD_BASENAME='"vgettimeofday_64"'
-DKBUILD_MODNAME='"vgettimeofday_64"'
-D__KBUILD_MODNAME=kmod_vgettimeofday_64 -c -o
arch/powerpc/kernel/vdso/vgettimeofday-64.o
arch/powerpc/kernel/vdso/vgettimeofday.c ; ./tools/objtool/objtool
mcount arch/powerpc/kernel/vdso/vgettimeofday-64.o


> +
> ifdef CONFIG_BPF
> ifdef CONFIG_DEBUG_INFO_BTF
> prepare: tools/bpf/resolve_btfids
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