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static_call: Add some validation 

Verify the text we're about to change is as we expect it to be.

Requested-by: Steven Rostedt <rostedt@goodmis.org>

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200818135805.161974981@infradead.org
This commit is contained in:
Peter Zijlstra 2020-08-18 15:57:50 +02:00 committed by Ingo Molnar
parent 5b06fd3bb9
commit 6c3fce794e
1 changed files with 26 additions and 2 deletions
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28
arch/x86/kernel/static_call.c
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@ -41,6 +41,26 @@ static void __static_call_transform(void *insn, enum insn_type type, void *func)
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)
{
/*
@ -60,11 +80,15 @@ void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
{
mutex_lock(&text_mutex);
if (tramp)
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)
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);
}