From 22e9e69cfc13112ddd3157b3b6bd2eb8c5728dab Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sat, 5 Sep 2026 10:43:57 +0200 Subject: [PATCH] entry: Guard syscall_enter_audit() invocation with CONFIG_AUDITSYSCALL A bunch of older cross compilers notably RISCV64 and S390 fail to eliminate the dead code when CONFIG_AUDITSYSCALL=n. The code in question is: if (unlikely(audit_context()) syscall_enter_audit(regs); and in case of CONFIG_AUDITSYSCALL=n: static inline struct audit_context *audit_context(void) { return NULL; } which should make the compiler eliminate the syscall_enter_audit() call. But a RISV64 GCC12 cross compiler translates that into: if (unlikely(audit_context())) 1c34: 00000097 auipc ra,0x0 1c38: 000080e7 jalr ra # 1c34 <.L785> 1c3c: c511 beqz a0,1c48 <.L787> syscall_enter_audit(regs); 1c3e: 8526 mv a0,s1 1c40: 00000097 auipc ra,0x0 1c44: 000080e7 jalr ra # 1c40 <.L785+0xc> and then claims in the failing link: include/asm-generic/preempt.h:54:(.noinstr.text+0x1a20): undefined reference to 'syscall_enter_audit' which is obviously hallucination. Add an explicit IS_ENABLED(CONFIG_AUDITSYSCALL) check into the condition to cure this compiler madness. Fixes: 6f25517010dd ("entry: Rework syscall_audit_enter()") Reported-by: kernel test robot Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Closes: https://lore.kernel.org/oe-kbuild-all/202609031938.ZvZZaRQy-lkp@intel.com/ Signed-off-by: Linux RISC-V bot --- include/linux/entry-common.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 6574b7183c0172..fa2854fed1f289 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -102,7 +102,14 @@ static __always_inline long syscall_trace_enter(struct pt_regs *regs, unsigned l if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT)) trace_syscall_enter(regs); - if (unlikely(audit_context())) + /* + * The config check works around broken compilers which fail to + * eliminate the dead code in case of CONFIG_AUDITSYSCALL=n as they + * insist on creating a always false runtime condition based on + * audit_context() which returns NULL in that case. The explicit + * IS_ENABLED() check makes that madness go away. + */ + if (IS_ENABLED(CONFIG_AUDITSYSCALL) && unlikely(audit_context())) syscall_enter_audit(regs); return true;