mirror of
https://github.com/torvalds/linux.git
synced 2024-12-03 17:41:22 +00:00
a945c8345e
In order to use static_call() to wire up x86_pmu, we need to initialize earlier, specifically before memory allocation works; copy some of the tricks from jump_label to enable this. Primarily we overload key->next to store a sites pointer when there are no modules, this avoids having to use kmalloc() to initialize the sites and allows us to run much earlier. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Link: https://lore.kernel.org/r/20200818135805.220737930@infradead.org
99 lines
2.1 KiB
C
99 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/static_call.h>
|
|
#include <linux/memory.h>
|
|
#include <linux/bug.h>
|
|
#include <asm/text-patching.h>
|
|
|
|
enum insn_type {
|
|
CALL = 0, /* site call */
|
|
NOP = 1, /* site cond-call */
|
|
JMP = 2, /* tramp / site tail-call */
|
|
RET = 3, /* tramp / site cond-tail-call */
|
|
};
|
|
|
|
static void __ref __static_call_transform(void *insn, enum insn_type type, void *func)
|
|
{
|
|
int size = CALL_INSN_SIZE;
|
|
const void *code;
|
|
|
|
switch (type) {
|
|
case CALL:
|
|
code = text_gen_insn(CALL_INSN_OPCODE, insn, func);
|
|
break;
|
|
|
|
case NOP:
|
|
code = ideal_nops[NOP_ATOMIC5];
|
|
break;
|
|
|
|
case JMP:
|
|
code = text_gen_insn(JMP32_INSN_OPCODE, insn, func);
|
|
break;
|
|
|
|
case RET:
|
|
code = text_gen_insn(RET_INSN_OPCODE, insn, func);
|
|
size = RET_INSN_SIZE;
|
|
break;
|
|
}
|
|
|
|
if (memcmp(insn, code, size) == 0)
|
|
return;
|
|
|
|
if (unlikely(system_state == SYSTEM_BOOTING))
|
|
return text_poke_early(insn, code, size);
|
|
|
|
text_poke_bp(insn, code, size, NULL);
|
|
}
|
|
|
|
static void __static_call_validate(void *insn, bool tail)
|
|
{
|
|
u8 opcode = *(u8 *)insn;
|
|
|
|
if (tail) {
|
|
if (opcode == JMP32_INSN_OPCODE ||
|
|
opcode == RET_INSN_OPCODE)
|
|
return;
|
|
} else {
|
|
if (opcode == CALL_INSN_OPCODE ||
|
|
!memcmp(insn, ideal_nops[NOP_ATOMIC5], 5))
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* If we ever trigger this, our text is corrupt, we'll probably not live long.
|
|
*/
|
|
WARN_ONCE(1, "unexpected static_call insn opcode 0x%x at %pS\n", opcode, insn);
|
|
}
|
|
|
|
static inline enum insn_type __sc_insn(bool null, bool tail)
|
|
{
|
|
/*
|
|
* Encode the following table without branches:
|
|
*
|
|
* tail null insn
|
|
* -----+-------+------
|
|
* 0 | 0 | CALL
|
|
* 0 | 1 | NOP
|
|
* 1 | 0 | JMP
|
|
* 1 | 1 | RET
|
|
*/
|
|
return 2*tail + null;
|
|
}
|
|
|
|
void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
|
|
{
|
|
mutex_lock(&text_mutex);
|
|
|
|
if (tramp) {
|
|
__static_call_validate(tramp, true);
|
|
__static_call_transform(tramp, __sc_insn(!func, true), func);
|
|
}
|
|
|
|
if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site) {
|
|
__static_call_validate(site, tail);
|
|
__static_call_transform(site, __sc_insn(!func, tail), func);
|
|
}
|
|
|
|
mutex_unlock(&text_mutex);
|
|
}
|
|
EXPORT_SYMBOL_GPL(arch_static_call_transform);
|