diff options
| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2020-08-18 15:57:44 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-09-01 09:58:05 +0200 |
| commit | e6d6c071f22de29e4993784fc00cd2202b7ba149 (patch) | |
| tree | bae18c77a906997cabae12110f0c759a28856a65 /arch/x86/include/asm/static_call.h | |
| parent | 6333e8f73b834f54e395a056e6002403f0862c51 (diff) | |
x86/static_call: Add out-of-line static call implementation
Add the x86 out-of-line static call implementation. For each key, a
permanent trampoline is created which is the destination for all static
calls for the given key. The trampoline has a direct jump which gets
patched by static_call_update() when the destination function changes.
[peterz: fixed trampoline, rewrote patching code]
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135804.804315175@infradead.org
Diffstat (limited to 'arch/x86/include/asm/static_call.h')
| -rw-r--r-- | arch/x86/include/asm/static_call.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/x86/include/asm/static_call.h b/arch/x86/include/asm/static_call.h new file mode 100644 index 000000000000..07aa8791cbfe --- /dev/null +++ b/arch/x86/include/asm/static_call.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_STATIC_CALL_H +#define _ASM_STATIC_CALL_H + +#include <asm/text-patching.h> + +/* + * For CONFIG_HAVE_STATIC_CALL, this is a permanent trampoline which + * does a direct jump to the function. The direct jump gets patched by + * static_call_update(). + */ +#define ARCH_DEFINE_STATIC_CALL_TRAMP(name, func) \ + asm(".pushsection .text, \"ax\" \n" \ + ".align 4 \n" \ + ".globl " STATIC_CALL_TRAMP_STR(name) " \n" \ + STATIC_CALL_TRAMP_STR(name) ": \n" \ + " .byte 0xe9 # jmp.d32 \n" \ + " .long " #func " - (. + 4) \n" \ + ".type " STATIC_CALL_TRAMP_STR(name) ", @function \n" \ + ".size " STATIC_CALL_TRAMP_STR(name) ", . - " STATIC_CALL_TRAMP_STR(name) " \n" \ + ".popsection \n") + +#endif /* _ASM_STATIC_CALL_H */ |