selftests/x86: Consolidate redundant signal helper functions

The x86 selftests frequently register and clean up signal handlers, but
the sethandler() and clearhandler() functions have been redundantly
copied across multiple .c files.

Move these functions to helpers.h to enable reuse across tests,
eliminating around 250 lines of duplicate code.

Converge the error handling by using ksft_exit_fail_msg(), which is
functionally equivalent with err() within the selftest framework.

This change is a prerequisite for the upcoming xstate selftest, which
requires signal handling for registering and cleaning up handlers.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226010731.2456-2-chang.seok.bae@intel.com

tools/testing/selftests/x86/amx.c

@@ -20,6 +20,7 @@
 #include <sys/uio.h>
 
 #include "../kselftest.h" /* For __cpuid_count() */
+#include "helpers.h"
 
 #ifndef __x86_64__
 # error This test is 64-bit only
@@ -61,30 +62,6 @@ static inline void xrstor(struct xsave_buffer *xbuf, uint64_t rfbm)
 /* err() exits and will not return */
 #define fatal_error(msg, ...)	err(1, "[FAIL]\t" msg, ##__VA_ARGS__)
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		fatal_error("sigaction");
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		fatal_error("sigaction");
-}
-
 #define XFEATURE_XTILECFG	17
 #define XFEATURE_XTILEDATA	18
 #define XFEATURE_MASK_XTILECFG	(1 << XFEATURE_XTILECFG)

tools/testing/selftests/x86/corrupt_xstate_header.c

@@ -18,6 +18,7 @@
 #include <sys/wait.h>
 
 #include "../kselftest.h" /* For __cpuid_count() */
+#include "helpers.h"
 
 static inline int xsave_enabled(void)
 {
@@ -29,19 +30,6 @@ static inline int xsave_enabled(void)
 	return ecx & (1U << 27);
 }
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static void sigusr1(int sig, siginfo_t *info, void *uc_void)
 {
 	ucontext_t *uc = uc_void;

tools/testing/selftests/x86/entry_from_vm86.c

@@ -24,31 +24,11 @@
 #include <errno.h>
 #include <sys/vm86.h>
 
+#include "helpers.h"
+
 static unsigned long load_addr = 0x10000;
 static int nerrs = 0;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static sig_atomic_t got_signal;
 
 static void sighandler(int sig, siginfo_t *info, void *ctx_void)

tools/testing/selftests/x86/fsgsbase.c

@@ -28,6 +28,8 @@
 #include <sys/wait.h>
 #include <setjmp.h>
 
+#include "helpers.h"
+
 #ifndef __x86_64__
 # error This test is 64-bit only
 #endif
@@ -39,28 +41,6 @@ static unsigned short *shared_scratch;
 
 static int nerrs;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
 {
 	ucontext_t *ctx = (ucontext_t*)ctx_void;

tools/testing/selftests/x86/helpers.h

@@ -2,8 +2,13 @@
 #ifndef __SELFTESTS_X86_HELPERS_H
 #define __SELFTESTS_X86_HELPERS_H
 
+#include <signal.h>
+#include <string.h>
+
 #include <asm/processor-flags.h>
 
+#include "../kselftest.h"
+
 static inline unsigned long get_eflags(void)
 {
 #ifdef __x86_64__
@@ -22,4 +27,27 @@ static inline void set_eflags(unsigned long eflags)
 #endif
 }
 
+static inline void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), int flags)
+{
+	struct sigaction sa;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		ksft_exit_fail_msg("sigaction failed");
+}
+
+static inline void clearhandler(int sig)
+{
+	struct sigaction sa;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		ksft_exit_fail_msg("sigaction failed");
+}
+
 #endif /* __SELFTESTS_X86_HELPERS_H */

tools/testing/selftests/x86/ioperm.c

@@ -20,31 +20,10 @@
 #include <sched.h>
 #include <sys/io.h>
 
+#include "helpers.h"
+
 static int nerrs = 0;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static jmp_buf jmpbuf;
 
 static void sigsegv(int sig, siginfo_t *si, void *ctx_void)

tools/testing/selftests/x86/iopl.c

@@ -20,31 +20,10 @@
 #include <sched.h>
 #include <sys/io.h>
 
+#include "helpers.h"
+
 static int nerrs = 0;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static jmp_buf jmpbuf;
 
 static void sigsegv(int sig, siginfo_t *si, void *ctx_void)

tools/testing/selftests/x86/ldt_gdt.c

@@ -26,6 +26,8 @@
 #include <asm/prctl.h>
 #include <sys/prctl.h>
 
+#include "helpers.h"
+
 #define AR_ACCESSED		(1<<8)
 
 #define AR_TYPE_RODATA		(0 * (1<<9))
@@ -506,20 +508,6 @@ static void fix_sa_restorer(int sig)
 }
 #endif
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-
-	fix_sa_restorer(sig);
-}
-
 static jmp_buf jmpbuf;
 
 static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
@@ -549,9 +537,11 @@ static void do_multicpu_tests(void)
 	}
 
 	sethandler(SIGSEGV, sigsegv, 0);
+	fix_sa_restorer(SIGSEGV);
 #ifdef __i386__
 	/* True 32-bit kernels send SIGILL instead of SIGSEGV on IRET faults. */
 	sethandler(SIGILL, sigsegv, 0);
+	fix_sa_restorer(SIGILL);
 #endif
 
 	printf("[RUN]\tCross-CPU LDT invalidation\n");

tools/testing/selftests/x86/mov_ss_trap.c

@@ -36,7 +36,7 @@
 #include <setjmp.h>
 #include <sys/prctl.h>
 
-#define X86_EFLAGS_RF (1UL << 16)
+#include "helpers.h"
 
 #if __x86_64__
 # define REG_IP REG_RIP
@@ -94,18 +94,6 @@ static void enable_watchpoint(void)
 	}
 }
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static char const * const signames[] = {
 	[SIGSEGV] = "SIGSEGV",
 	[SIGBUS] = "SIBGUS",

tools/testing/selftests/x86/ptrace_syscall.c

@@ -15,6 +15,8 @@
 #include <asm/ptrace-abi.h>
 #include <sys/auxv.h>
 
+#include "helpers.h"
+
 /* Bitness-agnostic defines for user_regs_struct fields. */
 #ifdef __x86_64__
 # define user_syscall_nr	orig_rax
@@ -93,18 +95,6 @@ static siginfo_t wait_trap(pid_t chld)
 	return si;
 }
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static void setsigign(int sig, int flags)
 {
 	struct sigaction sa;
@@ -116,16 +106,6 @@ static void setsigign(int sig, int flags)
 		err(1, "sigaction");
 }
 
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 #ifdef __x86_64__
 # define REG_BP REG_RBP
 #else

tools/testing/selftests/x86/sigaltstack.c

@@ -14,6 +14,8 @@
 #include <sys/resource.h>
 #include <setjmp.h>
 
+#include "helpers.h"
+
 /* sigaltstack()-enforced minimum stack */
 #define ENFORCED_MINSIGSTKSZ	2048
 
@@ -27,30 +29,6 @@ static bool sigalrm_expected;
 
 static unsigned long at_minstack_size;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static int setup_altstack(void *start, unsigned long size)
 {
 	stack_t ss;

tools/testing/selftests/x86/sigreturn.c

@@ -46,6 +46,8 @@
 #include <sys/ptrace.h>
 #include <sys/user.h>
 
+#include "helpers.h"
+
 /* Pull in AR_xyz defines. */
 typedef unsigned int u32;
 typedef unsigned short u16;
@@ -138,28 +140,6 @@ static unsigned short LDT3(int idx)
 	return (idx << 3) | 7;
 }
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static void add_ldt(const struct user_desc *desc, unsigned short *var,
 		    const char *name)
 {

tools/testing/selftests/x86/single_step_syscall.c

@@ -33,28 +33,6 @@
 
 #include "helpers.h"
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static volatile sig_atomic_t sig_traps, sig_eflags;
 sigjmp_buf jmpbuf;
 

tools/testing/selftests/x86/syscall_arg_fault.c

@@ -17,18 +17,6 @@
 
 #include "helpers.h"
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static sigjmp_buf jmpbuf;
 
 static volatile sig_atomic_t n_errs;

tools/testing/selftests/x86/syscall_nt.c

@@ -18,18 +18,6 @@
 
 static unsigned int nerrs;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static void sigtrap(int sig, siginfo_t *si, void *ctx_void)
 {
 }

tools/testing/selftests/x86/sysret_rip.c

@@ -22,6 +22,8 @@
 #include <sys/mman.h>
 #include <assert.h>
 
+#include "helpers.h"
+
 /*
  * These items are in clang_helpers_64.S, in order to avoid clang inline asm
  * limitations:
@@ -31,28 +33,6 @@ extern const char test_page[];
 
 static void const *current_test_page_addr = test_page;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
-static void clearhandler(int sig)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_handler = SIG_DFL;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 /* State used by our signal handlers. */
 static gregset_t initial_regs;
 

tools/testing/selftests/x86/test_vsyscall.c

@@ -310,19 +310,6 @@ static void test_getcpu(int cpu)
 static jmp_buf jmpbuf;
 static volatile unsigned long segv_err;
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		ksft_exit_fail_msg("sigaction failed\n");
-}
-
 static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
 {
 	ucontext_t *ctx = (ucontext_t *)ctx_void;

tools/testing/selftests/x86/unwind_vdso.c

@@ -43,18 +43,6 @@ int main()
 #include <dlfcn.h>
 #include <unwind.h>
 
-static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
-		       int flags)
-{
-	struct sigaction sa;
-	memset(&sa, 0, sizeof(sa));
-	sa.sa_sigaction = handler;
-	sa.sa_flags = SA_SIGINFO | flags;
-	sigemptyset(&sa.sa_mask);
-	if (sigaction(sig, &sa, 0))
-		err(1, "sigaction");
-}
-
 static volatile sig_atomic_t nerrs;
 static unsigned long sysinfo;
 static bool got_sysinfo = false;