[PATCH 5.19 1028/1157] x86/entry: Build thunk_$(BITS) only if CONFIG_PREEMPTION=y
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2022-08-16 00:52:15
Also in:
lkml
Subsystem:
the rest, user-mode linux (uml), x86 architecture (32-bit and 64-bit), x86 entry code · Maintainers:
Linus Torvalds, Richard Weinberger, Anton Ivanov, Johannes Berg, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski
From: Andrea Righi <redacted> [ Upstream commit de979c83574abf6e78f3fa65b716515c91b2613d ] With CONFIG_PREEMPTION disabled, arch/x86/entry/thunk_$(BITS).o becomes an empty object file. With some old versions of binutils (i.e., 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 <redacted> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/Ys/Ke7EWjcX+ZlXO@arighi-desktop Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/x86/entry/Makefile | 3 ++- arch/x86/entry/thunk_32.S | 2 -- arch/x86/entry/thunk_64.S | 4 ---- arch/x86/um/Makefile | 3 ++- 4 files changed, 4 insertions(+), 8 deletions(-)
diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile
index eeadbd7d92cc..ca2fe186994b 100644
--- a/arch/x86/entry/Makefile
+++ b/arch/x86/entry/Makefile@@ -11,12 +11,13 @@ CFLAGS_REMOVE_common.o = $(CC_FLAGS_FTRACE) CFLAGS_common.o += -fno-stack-protector -obj-y := entry.o entry_$(BITS).o thunk_$(BITS).o syscall_$(BITS).o +obj-y := entry.o 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 7591bab060f7..ff6e7003da97 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 505b488fcc65..f38b07d2768b 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
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index ba5789c35809..a8cde4e8ab11 100644
--- a/arch/x86/um/Makefile
+++ b/arch/x86/um/Makefile@@ -28,7 +28,8 @@ else obj-y += syscalls_64.o vdso/ -subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o ../entry/thunk_64.o +subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o +subarch-$(CONFIG_PREEMPTION) += ../entry/thunk_64.o endif
--
2.35.1