6.6-stable review patch. If anyone has any objections, please let me know.
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From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit a8df7d0ef92eca28c610206c6748daf537ac0586 ]
The !CONFIG_IA32_EMULATION version of xen_entry_SYSCALL_compat() ends with a SYSCALL instruction which is classified by objtool as INSN_CONTEXT_SWITCH.
Unlike validate_branch(), validate_unret() doesn't consider INSN_CONTEXT_SWITCH in a non-function to be a dead end, so it keeps going past the end of xen_entry_SYSCALL_compat(), resulting in the following warning:
vmlinux.o: warning: objtool: xen_reschedule_interrupt+0x2a: RET before UNTRAIN
Fix that by adding INSN_CONTEXT_SWITCH handling to validate_unret() to match what validate_branch() is already doing.
Fixes: a09a6e2399ba ("objtool: Add entry UNRET validation") Reported-by: Andrew Cooper andrew.cooper3@citrix.com Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Link: https://lore.kernel.org/r/f5eda46fd09f15b1f5cde3d9ae3b92b958342add.174409521... Signed-off-by: Sasha Levin sashal@kernel.org --- tools/objtool/check.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 9102ad5985cc0..8ba5bcfd5cd57 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3926,6 +3926,11 @@ static int validate_unret(struct objtool_file *file, struct instruction *insn) WARN_INSN(insn, "RET before UNTRAIN"); return 1;
+ case INSN_CONTEXT_SWITCH: + if (insn_func(insn)) + break; + return 0; + case INSN_NOP: if (insn->retpoline_safe) return 0;