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
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@ -41,6 +41,26 @@ static void __static_call_transform(void *insn, enum insn_type type, void *func)
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text_poke_bp(insn, code, size, NULL);
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}
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static void __static_call_validate(void *insn, bool tail)
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{
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u8 opcode = *(u8 *)insn;
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if (tail) {
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if (opcode == JMP32_INSN_OPCODE ||
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opcode == RET_INSN_OPCODE)
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return;
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} else {
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if (opcode == CALL_INSN_OPCODE ||
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!memcmp(insn, ideal_nops[NOP_ATOMIC5], 5))
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return;
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}
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/*
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* If we ever trigger this, our text is corrupt, we'll probably not live long.
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*/
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WARN_ONCE(1, "unexpected static_call insn opcode 0x%x at %pS\n", opcode, insn);
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}
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static inline enum insn_type __sc_insn(bool null, bool tail)
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{
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/*
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@ -60,11 +80,15 @@ void arch_static_call_transform(void *site, void *tramp, void *func, bool tail)
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{
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mutex_lock(&text_mutex);
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if (tramp)
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if (tramp) {
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__static_call_validate(tramp, true);
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__static_call_transform(tramp, __sc_insn(!func, true), func);
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}
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if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site)
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if (IS_ENABLED(CONFIG_HAVE_STATIC_CALL_INLINE) && site) {
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__static_call_validate(site, tail);
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__static_call_transform(site, __sc_insn(!func, tail), func);
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}
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mutex_unlock(&text_mutex);
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}
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