Commit e6d6c071 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar

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: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20200818135804.804315175@infradead.org
parent 6333e8f7
......@@ -215,6 +215,7 @@ config X86
select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_STACKPROTECTOR if CC_HAS_SANE_STACKPROTECTOR
select HAVE_STACK_VALIDATION if X86_64
select HAVE_STATIC_CALL
select HAVE_RSEQ
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UNSTABLE_SCHED_CLOCK
......
/* 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 */
......@@ -68,6 +68,7 @@ obj-y += tsc.o tsc_msr.o io_delay.o rtc.o
obj-y += pci-iommu_table.o
obj-y += resource.o
obj-y += irqflags.o
obj-y += static_call.o
obj-y += process.o
obj-y += fpu/
......
// SPDX-License-Identifier: GPL-2.0
#include <linux/static_call.h>
#include <linux/memory.h>
#include <linux/bug.h>
#include <asm/text-patching.h>
static void __static_call_transform(void *insn, u8 opcode, void *func)
{
const void *code = text_gen_insn(opcode, insn, func);
if (WARN_ONCE(*(u8 *)insn != opcode,
"unexpected static call insn opcode 0x%x at %pS\n",
opcode, insn))
return;
if (memcmp(insn, code, CALL_INSN_SIZE) == 0)
return;
text_poke_bp(insn, code, CALL_INSN_SIZE, NULL);
}
void arch_static_call_transform(void *site, void *tramp, void *func)
{
mutex_lock(&text_mutex);
if (tramp)
__static_call_transform(tramp, JMP32_INSN_OPCODE, func);
mutex_unlock(&text_mutex);
}
EXPORT_SYMBOL_GPL(arch_static_call_transform);
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment