diff options
| author | Nadav Amit <namit@vmware.com> | 2018-10-05 23:27:18 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-10-06 16:52:17 +0300 |
| commit | 5bdcd510c2ac9efaf55c4cbd8d46421d8e2320cd (patch) | |
| tree | db62e809d2470e86fa7f87425b24fc61d151b8cc /arch/x86/entry | |
| parent | d5a581d84ae6b8a4a740464b80d8d9cf1e7947b2 (diff) | |
| download | linux-5bdcd510c2ac9efaf55c4cbd8d46421d8e2320cd.tar.xz | |
x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs
As described in:
77b0bf55bc67: ("kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs")
GCC's inlining heuristics are broken with common asm() patterns used in
kernel code, resulting in the effective disabling of inlining.
The workaround is to set an assembly macro and call it from the inline
assembly block - which is also a minor cleanup for the jump-label code.
As a result the code size is slightly increased, but inlining decisions
are better:
text data bss dec hex filename
18163528 10226300 2957312 31347140 1de51c4 ./vmlinux before
18163608 10227348 2957312 31348268 1de562c ./vmlinux after (+1128)
And functions such as intel_pstate_adjust_policy_max(),
kvm_cpu_accept_dm_intr(), kvm_register_readl() are inlined.
Tested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181005202718.229565-4-namit@vmware.com
Link: https://lore.kernel.org/lkml/20181003213100.189959-11-namit@vmware.com/T/#u
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/calling.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 352e70cd33e8..708b46a54578 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -338,7 +338,7 @@ For 32-bit we have the following conventions - kernel is built with .macro CALL_enter_from_user_mode #ifdef CONFIG_CONTEXT_TRACKING #ifdef HAVE_JUMP_LABEL - STATIC_JUMP_IF_FALSE .Lafter_call_\@, context_tracking_enabled, def=0 + STATIC_BRANCH_JMP l_yes=.Lafter_call_\@, key=context_tracking_enabled, branch=1 #endif call enter_from_user_mode .Lafter_call_\@: |