The following commit has been merged into the core/static_call branch of tip:
Commit-ID: 6c3fce794e9d2a5ce3a948962d0808a459c40a84 Gitweb: https://git.kernel.org/tip/6c3fce794e9d2a5ce3a948962d0808a459c40a84 Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Tue, 18 Aug 2020 15:57:50 +02:00 Committer: Ingo Molnar <mi...@kernel.org> CommitterDate: Tue, 01 Sep 2020 09:58:06 +02:00 static_call: Add some validation Verify the text we're about to change is as we expect it to be. Requested-by: Steven Rostedt <rost...@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Signed-off-by: Ingo Molnar <mi...@kernel.org> Link: https://lore.kernel.org/r/20200818135805.161974...@infradead.org --- arch/x86/kernel/static_call.c | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c index 60a325c..55140d8 100644 --- a/arch/x86/kernel/static_call.c +++ b/arch/x86/kernel/static_call.c @@ -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); }
