The following commit has been merged into the x86/entry branch of tip: Commit-ID: e6d92b6680371ae1aeeb6c5eb2387fdc5d9a2c89 Gitweb: https://git.kernel.org/tip/e6d92b6680371ae1aeeb6c5eb2387fdc5d9a2c89 Author: Andrea Righi <andrea.ri...@canonical.com> AuthorDate: Thu, 14 Jan 2021 12:48:35 +01:00 Committer: Ingo Molnar <mi...@kernel.org> CommitterDate: Thu, 21 Jan 2021 08:11:52 +01:00
x86/entry: Build thunk_$(BITS) only if CONFIG_PREEMPTION=y With CONFIG_PREEMPTION disabled, arch/x86/entry/thunk_64.o is just an empty object file. With the newer binutils (tested with 2.35.90.20210113-1ubuntu1) the GNU assembler doesn't generate a symbol table for empty object files and objtool fails with the following error when a valid symbol table cannot be found: arch/x86/entry/thunk_64.o: warning: objtool: missing symbol table To prevent this from happening, build thunk_$(BITS).o only if CONFIG_PREEMPTION is enabled. BugLink: https://bugs.launchpad.net/bugs/1911359 Fixes: 320100a5ffe5 ("x86/entry: Remove the TRACE_IRQS cruft") Signed-off-by: Andrea Righi <andrea.ri...@canonical.com> Signed-off-by: Ingo Molnar <mi...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Link: https://lore.kernel.org/r/YAAvk0UQelq0Ae7+@xps-13-7390 --- arch/x86/entry/Makefile | 3 ++- arch/x86/entry/thunk_32.S | 2 -- arch/x86/entry/thunk_64.S | 4 ---- 3 files changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile index 08bf95d..83c98da 100644 --- a/arch/x86/entry/Makefile +++ b/arch/x86/entry/Makefile @@ -21,12 +21,13 @@ CFLAGS_syscall_64.o += $(call cc-option,-Wno-override-init,) CFLAGS_syscall_32.o += $(call cc-option,-Wno-override-init,) CFLAGS_syscall_x32.o += $(call cc-option,-Wno-override-init,) -obj-y := entry_$(BITS).o thunk_$(BITS).o syscall_$(BITS).o +obj-y := entry_$(BITS).o syscall_$(BITS).o obj-y += common.o obj-y += vdso/ obj-y += vsyscall/ +obj-$(CONFIG_PREEMPTION) += thunk_$(BITS).o obj-$(CONFIG_IA32_EMULATION) += entry_64_compat.o syscall_32.o obj-$(CONFIG_X86_X32_ABI) += syscall_x32.o diff --git a/arch/x86/entry/thunk_32.S b/arch/x86/entry/thunk_32.S index f1f96d4..5997ec0 100644 --- a/arch/x86/entry/thunk_32.S +++ b/arch/x86/entry/thunk_32.S @@ -29,10 +29,8 @@ SYM_CODE_START_NOALIGN(\name) SYM_CODE_END(\name) .endm -#ifdef CONFIG_PREEMPTION THUNK preempt_schedule_thunk, preempt_schedule THUNK preempt_schedule_notrace_thunk, preempt_schedule_notrace EXPORT_SYMBOL(preempt_schedule_thunk) EXPORT_SYMBOL(preempt_schedule_notrace_thunk) -#endif diff --git a/arch/x86/entry/thunk_64.S b/arch/x86/entry/thunk_64.S index 496b11e..9d543c4 100644 --- a/arch/x86/entry/thunk_64.S +++ b/arch/x86/entry/thunk_64.S @@ -31,14 +31,11 @@ SYM_FUNC_END(\name) _ASM_NOKPROBE(\name) .endm -#ifdef CONFIG_PREEMPTION THUNK preempt_schedule_thunk, preempt_schedule THUNK preempt_schedule_notrace_thunk, preempt_schedule_notrace EXPORT_SYMBOL(preempt_schedule_thunk) EXPORT_SYMBOL(preempt_schedule_notrace_thunk) -#endif -#ifdef CONFIG_PREEMPTION SYM_CODE_START_LOCAL_NOALIGN(__thunk_restore) popq %r11 popq %r10 @@ -53,4 +50,3 @@ SYM_CODE_START_LOCAL_NOALIGN(__thunk_restore) ret _ASM_NOKPROBE(__thunk_restore) SYM_CODE_END(__thunk_restore) -#endif
