* [PATCH v8 4/6] selftest/sigaltstack: Use the AT_MINSIGSTKSZ aux vector if available
[not found] <20210422044856.27250-1-chang.seok.bae@intel.com>
@ 2021-04-22 4:48 ` Chang S. Bae
2021-04-22 4:48 ` [PATCH v8 6/6] selftest/x86/signal: Include test cases for validating sigaltstack Chang S. Bae
1 sibling, 0 replies; 2+ messages in thread
From: Chang S. Bae @ 2021-04-22 4:48 UTC (permalink / raw)
To: bp, tglx, mingo, luto, x86
Cc: len.brown, dave.hansen, hjl.tools, Dave.Martin, jannh, mpe,
carlos, tony.luck, ravi.v.shankar, libc-alpha, linux-arch,
linux-api, linux-kernel, chang.seok.bae, linux-kselftest
The SIGSTKSZ constant may not represent enough stack size in some
architectures as the hardware state size grows.
Use getauxval(AT_MINSIGSTKSZ) to increase the stack size.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Cc: linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
Changes from v5:
* Added as a new patch.
---
tools/testing/selftests/sigaltstack/sas.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/tools/testing/selftests/sigaltstack/sas.c b/tools/testing/selftests/sigaltstack/sas.c
index 8934a3766d20..c53b070755b6 100644
--- a/tools/testing/selftests/sigaltstack/sas.c
+++ b/tools/testing/selftests/sigaltstack/sas.c
@@ -17,6 +17,7 @@
#include <string.h>
#include <assert.h>
#include <errno.h>
+#include <sys/auxv.h>
#include "../kselftest.h"
@@ -24,6 +25,11 @@
#define SS_AUTODISARM (1U << 31)
#endif
+#ifndef AT_MINSIGSTKSZ
+#define AT_MINSIGSTKSZ 51
+#endif
+
+static unsigned int stack_size;
static void *sstack, *ustack;
static ucontext_t uc, sc;
static const char *msg = "[OK]\tStack preserved";
@@ -47,7 +53,7 @@ void my_usr1(int sig, siginfo_t *si, void *u)
#endif
if (sp < (unsigned long)sstack ||
- sp >= (unsigned long)sstack + SIGSTKSZ) {
+ sp >= (unsigned long)sstack + stack_size) {
ksft_exit_fail_msg("SP is not on sigaltstack\n");
}
/* put some data on stack. other sighandler will try to overwrite it */
@@ -108,6 +114,10 @@ int main(void)
stack_t stk;
int err;
+ /* Make sure more than the required minimum. */
+ stack_size = getauxval(AT_MINSIGSTKSZ) + SIGSTKSZ;
+ ksft_print_msg("[NOTE]\tthe stack size is %lu\n", stack_size);
+
ksft_print_header();
ksft_set_plan(3);
@@ -117,7 +127,7 @@ int main(void)
sigaction(SIGUSR1, &act, NULL);
act.sa_sigaction = my_usr2;
sigaction(SIGUSR2, &act, NULL);
- sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
+ sstack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
if (sstack == MAP_FAILED) {
ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
@@ -139,7 +149,7 @@ int main(void)
}
stk.ss_sp = sstack;
- stk.ss_size = SIGSTKSZ;
+ stk.ss_size = stack_size;
stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;
err = sigaltstack(&stk, NULL);
if (err) {
@@ -161,7 +171,7 @@ int main(void)
}
}
- ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
+ ustack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
if (ustack == MAP_FAILED) {
ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
@@ -170,7 +180,7 @@ int main(void)
getcontext(&uc);
uc.uc_link = NULL;
uc.uc_stack.ss_sp = ustack;
- uc.uc_stack.ss_size = SIGSTKSZ;
+ uc.uc_stack.ss_size = stack_size;
makecontext(&uc, switch_fn, 0);
raise(SIGUSR1);
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH v8 6/6] selftest/x86/signal: Include test cases for validating sigaltstack
[not found] <20210422044856.27250-1-chang.seok.bae@intel.com>
2021-04-22 4:48 ` [PATCH v8 4/6] selftest/sigaltstack: Use the AT_MINSIGSTKSZ aux vector if available Chang S. Bae
@ 2021-04-22 4:48 ` Chang S. Bae
1 sibling, 0 replies; 2+ messages in thread
From: Chang S. Bae @ 2021-04-22 4:48 UTC (permalink / raw)
To: bp, tglx, mingo, luto, x86
Cc: len.brown, dave.hansen, hjl.tools, Dave.Martin, jannh, mpe,
carlos, tony.luck, ravi.v.shankar, libc-alpha, linux-arch,
linux-api, linux-kernel, chang.seok.bae, linux-kselftest
The test measures the kernel's signal delivery with different (enough vs.
insufficient) stack sizes.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
Changes from v3:
* Revised test messages again (Borislav Petkov)
Changes from v2:
* Revised test messages (Borislav Petkov)
---
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/sigaltstack.c | 128 ++++++++++++++++++++++
2 files changed, 129 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/x86/sigaltstack.c
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 333980375bc7..65bba2ae86ee 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -13,7 +13,7 @@ CAN_BUILD_WITH_NOPIE := $(shell ./check_cc.sh $(CC) trivial_program.c -no-pie)
TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt test_mremap_vdso \
check_initial_reg_state sigreturn iopl ioperm \
test_vsyscall mov_ss_trap \
- syscall_arg_fault fsgsbase_restore
+ syscall_arg_fault fsgsbase_restore sigaltstack
TARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
vdso_restorer
diff --git a/tools/testing/selftests/x86/sigaltstack.c b/tools/testing/selftests/x86/sigaltstack.c
new file mode 100644
index 000000000000..f689af75e979
--- /dev/null
+++ b/tools/testing/selftests/x86/sigaltstack.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define _GNU_SOURCE
+#include <signal.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#include <err.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/mman.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+#include <sys/resource.h>
+#include <setjmp.h>
+
+/* sigaltstack()-enforced minimum stack */
+#define ENFORCED_MINSIGSTKSZ 2048
+
+#ifndef AT_MINSIGSTKSZ
+# define AT_MINSIGSTKSZ 51
+#endif
+
+static int nerrs;
+
+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;
+
+ memset(&ss, 0, sizeof(ss));
+ ss.ss_size = size;
+ ss.ss_sp = start;
+
+ return sigaltstack(&ss, NULL);
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
+{
+ if (sigalrm_expected) {
+ printf("[FAIL]\tWrong signal delivered: SIGSEGV (expected SIGALRM).");
+ nerrs++;
+ } else {
+ printf("[OK]\tSIGSEGV signal delivered.\n");
+ }
+
+ siglongjmp(jmpbuf, 1);
+}
+
+static void sigalrm(int sig, siginfo_t *info, void *ctx_void)
+{
+ if (!sigalrm_expected) {
+ printf("[FAIL]\tWrong signal delivered: SIGALRM (expected SIGSEGV).");
+ nerrs++;
+ } else {
+ printf("[OK]\tSIGALRM signal delivered.\n");
+ }
+}
+
+static void test_sigaltstack(void *altstack, unsigned long size)
+{
+ if (setup_altstack(altstack, size))
+ err(1, "sigaltstack()");
+
+ sigalrm_expected = (size > at_minstack_size) ? true : false;
+
+ sethandler(SIGSEGV, sigsegv, 0);
+ sethandler(SIGALRM, sigalrm, SA_ONSTACK);
+
+ if (!sigsetjmp(jmpbuf, 1)) {
+ printf("[RUN]\tTest an alternate signal stack of %ssufficient size.\n",
+ sigalrm_expected ? "" : "in");
+ printf("\tRaise SIGALRM. %s is expected to be delivered.\n",
+ sigalrm_expected ? "It" : "SIGSEGV");
+ raise(SIGALRM);
+ }
+
+ clearhandler(SIGALRM);
+ clearhandler(SIGSEGV);
+}
+
+int main(void)
+{
+ void *altstack;
+
+ at_minstack_size = getauxval(AT_MINSIGSTKSZ);
+
+ altstack = mmap(NULL, at_minstack_size + SIGSTKSZ, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+ if (altstack == MAP_FAILED)
+ err(1, "mmap()");
+
+ if ((ENFORCED_MINSIGSTKSZ + 1) < at_minstack_size)
+ test_sigaltstack(altstack, ENFORCED_MINSIGSTKSZ + 1);
+
+ test_sigaltstack(altstack, at_minstack_size + SIGSTKSZ);
+
+ return nerrs == 0 ? 0 : 1;
+}
--
2.17.1
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2021-04-22 4:48 ` [PATCH v8 4/6] selftest/sigaltstack: Use the AT_MINSIGSTKSZ aux vector if available Chang S. Bae
2021-04-22 4:48 ` [PATCH v8 6/6] selftest/x86/signal: Include test cases for validating sigaltstack Chang S. Bae
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