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.righi@xxxxxxxxxxxxx>
AuthorDate: Thu, 14 Jan 2021 12:48:35 +01:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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.righi@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
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
|