Ping? On Mon, Jan 21, 2019 at 10:53:38AM +0100, Borislav Petkov wrote: > From: Borislav Petkov <bp@xxxxxxx> > > Modern gcc adds view assignments, reset assertion checking in .loc > directives and a couple more additional debug markers, which clutters > the asm output unnecessarily: > > For example: > > bsp_resume: > .LFB3466: > .loc 1 1868 1 is_stmt 1 view -0 > .cfi_startproc > .loc 1 1869 2 view .LVU73 > # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) > .loc 1 1869 14 is_stmt 0 view .LVU74 > movq this_cpu(%rip), %rax # this_cpu, this_cpu > movq 64(%rax), %rax # this_cpu.94_1->c_bsp_resume, _2 > # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) > .loc 1 1869 5 view .LVU75 > testq %rax, %rax # _2 > je .L8 #, > .loc 1 1870 3 is_stmt 1 view .LVU76 > movq $boot_cpu_data, %rdi #, > jmp __x86_indirect_thunk_rax > > or > .loc 2 57 9 view .LVU478 > .loc 2 57 9 view .LVU479 > .loc 2 57 9 view .LVU480 > .loc 2 57 9 view .LVU481 > .LBB1385: > .LBB1383: > .LBB1379: > .LBB1377: > .LBB1375: > .loc 2 57 9 view .LVU482 > .loc 2 57 9 view .LVU483 > movl %edi, %edx # cpu, cpu > .LVL87: > .loc 2 57 9 is_stmt 0 view .LVU484 > > That MOV in there is drowned in debugging information and latter makes > it hard to follow the asm. And that DWARF info is not really needed for > asm output staring. > > Disable the debug information generation which clutters the asm output > unnecessarily: > > bsp_resume: > .LFB3466: > .loc 1 1868 1 > # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) > .loc 1 1869 14 > movq this_cpu(%rip), %rax # this_cpu, this_cpu > movq 64(%rax), %rax # this_cpu.94_1->c_bsp_resume, _2 > # arch/x86/kernel/cpu/common.c:1869: if (this_cpu->c_bsp_resume) > .loc 1 1869 5 > testq %rax, %rax # _2 > je .L8 #, > # arch/x86/kernel/cpu/common.c:1870: this_cpu->c_bsp_resume(&boot_cpu_data); > .loc 1 1870 3 > movq $boot_cpu_data, %rdi #, > jmp __x86_indirect_thunk_rax > > Signed-off-by: Borislav Petkov <bp@xxxxxxx> > Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> > Cc: Michal Marek <michal.lkml@xxxxxxxxxxx> > Cc: linux-kbuild@xxxxxxxxxxxxxxx > --- > scripts/Makefile.build | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/scripts/Makefile.build b/scripts/Makefile.build > index fd03d60f6c5a..4f33fdab89d2 100644 > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -103,8 +103,12 @@ modkern_cflags = \ > $(KBUILD_CFLAGS_KERNEL) $(CFLAGS_KERNEL)) > quiet_modtag = $(if $(part-of-module),[M], ) > > +disable_extra_cc_dbg := $(call cc-option,-gno-as-locview-support) > +disable_extra_cc_dbg += $(call cc-option,-fno-dwarf2-cfi-asm) > +disable_extra_cc_dbg += $(call cc-option,-feliminate-unused-debug-symbols) > +disable_extra_cc_dbg += $(call cc-option,-gno-statement-frontiers) > quiet_cmd_cc_s_c = CC $(quiet_modtag) $@ > -cmd_cc_s_c = $(CC) $(c_flags) $(DISABLE_LTO) -fverbose-asm -S -o $@ $< > +cmd_cc_s_c = $(CC) $(c_flags) $(DISABLE_LTO) $(disable_extra_cc_dbg) -fverbose-asm -S -o $@ $< > > $(obj)/%.s: $(src)/%.c FORCE > $(call if_changed_dep,cc_s_c) > -- > 2.19.1 > -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.