2023-05-30 23:26:01

by Josh Poimboeuf

Subject: [PATCH] x86/entry: Move thunk restore code into thunk functions

There's no need for both thunk functions to jump to the same shared
thunk restore code which lives outside the thunk function boundaries.
It disrupts i-cache locality and confuses objtool. Keep it simple by
keeping each thunk's restore code self-contained within the function.

Fixes a bunch of false positive "missing __noreturn" warnings like:

vmlinux.o: warning: objtool: do_arch_prctl_common+0xf4: preempt_schedule_thunk() is missing a __noreturn annotation

Fixes: fedb724c3db5 ("objtool: Detect missing __noreturn annotations")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Signed-off-by: Josh Poimboeuf <[email protected]>
---
arch/x86/entry/thunk_64.S | 20 ++++++++------------
1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/arch/x86/entry/thunk_64.S b/arch/x86/entry/thunk_64.S
index 5e37f41e5f14..27b5da2111ac 100644
--- a/arch/x86/entry/thunk_64.S
+++ b/arch/x86/entry/thunk_64.S
@@ -26,17 +26,7 @@ SYM_FUNC_START(\name)
pushq %r11

call \func
- jmp __thunk_restore
-SYM_FUNC_END(\name)
- _ASM_NOKPROBE(\name)
- .endm

- 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)
-
-SYM_CODE_START_LOCAL(__thunk_restore)
popq %r11
popq %r10
popq %r9
@@ -48,5 +38,11 @@ SYM_CODE_START_LOCAL(__thunk_restore)
popq %rdi
popq %rbp
RET
- _ASM_NOKPROBE(__thunk_restore)
-SYM_CODE_END(__thunk_restore)
+SYM_FUNC_END(\name)
+ _ASM_NOKPROBE(\name)
+ .endm
+
+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)
--
2.40.1

2023-06-09 07:58:58

by tip-bot2 for Alexey Makhalov

Subject: [tip: objtool/core] x86/entry: Move thunk restore code into thunk functions

The following commit has been merged into the objtool/core branch of tip:

Commit-ID: ac27ecf68a1ada240bb71531dc2d30cde04ad70a
Gitweb: https://git.kernel.org/tip/ac27ecf68a1ada240bb71531dc2d30cde04ad70a
Author: Josh Poimboeuf <[email protected]>
AuthorDate: Tue, 30 May 2023 16:07:41 -07:00
Committer: Josh Poimboeuf <[email protected]>
CommitterDate: Wed, 07 Jun 2023 09:54:45 -07:00

x86/entry: Move thunk restore code into thunk functions

There's no need for both thunk functions to jump to the same shared
thunk restore code which lives outside the thunk function boundaries.
It disrupts i-cache locality and confuses objtool. Keep it simple by
keeping each thunk's restore code self-contained within the function.

Fixes a bunch of false positive "missing __noreturn" warnings like:

vmlinux.o: warning: objtool: do_arch_prctl_common+0xf4: preempt_schedule_thunk() is missing a __noreturn annotation

Fixes: fedb724c3db5 ("objtool: Detect missing __noreturn annotations")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Link: https://lore.kernel.org/r/46aa8aeb716f302e22e1673ae15ee6fe050b41f4.1685488050.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <[email protected]>
---
arch/x86/entry/thunk_64.S | 20 ++++++++------------
1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/arch/x86/entry/thunk_64.S b/arch/x86/entry/thunk_64.S
index 5e37f41..27b5da2 100644
--- a/arch/x86/entry/thunk_64.S
+++ b/arch/x86/entry/thunk_64.S
@@ -26,17 +26,7 @@ SYM_FUNC_START(\name)
pushq %r11

call \func
- jmp __thunk_restore
-SYM_FUNC_END(\name)
- _ASM_NOKPROBE(\name)
- .endm
-
- 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)

-SYM_CODE_START_LOCAL(__thunk_restore)
popq %r11
popq %r10
popq %r9
@@ -48,5 +38,11 @@ SYM_CODE_START_LOCAL(__thunk_restore)
popq %rdi
popq %rbp
RET
- _ASM_NOKPROBE(__thunk_restore)
-SYM_CODE_END(__thunk_restore)
+SYM_FUNC_END(\name)
+ _ASM_NOKPROBE(\name)
+ .endm
+
+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)