Messages in this thread Patch in this message | | | From | Rasmus Villemoes <> | Subject | [PATCH] x86: tell the world boot_params is 16-byte aligned | Date | Fri, 8 May 2015 15:42:33 +0200 |
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It doesn't matter much, but this disassembly makes me cry a little bit:
ffffffff81f21223 <copy_bootdata>: ffffffff81f21223: 55 push %rbp ffffffff81f21224: 48 c7 c0 40 c2 02 82 mov $0xffffffff8202c240,%rax ffffffff81f2122b: 48 89 fe mov %rdi,%rsi ffffffff81f2122e: a8 01 test $0x1,%al
The reason is that boot_params is defined with __attribute__((aligned(16))) in boot/main.c, but other translation units only see the packed attribute on the definition of struct boot_params, so assume the worst. Making the de facto alignment public has this effect:
$ scripts/bloat-o-meter /tmp/vmlinux.{defconfig,align} add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-230 (-230) function old new delta copy_bootdata 444 214 -230
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- arch/x86/include/asm/setup.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h index f69e06b283fb..dcd6d5fc2f12 100644 --- a/arch/x86/include/asm/setup.h +++ b/arch/x86/include/asm/setup.h @@ -64,7 +64,7 @@ static inline void x86_ce4100_early_setup(void) { } /* * This is set up by the setup-routine at boot-time */ -extern struct boot_params boot_params; +extern struct boot_params boot_params __attribute__((aligned(16))); static inline bool kaslr_enabled(void) { -- 2.1.3
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