Merge cherrypicks of ['googleplex-android-review.googlesource.com/33294988', 'googleplex-android-review.googlesource.com/33313547'] into 25Q2-release.
Change-Id: I4cbf70423928c5722ce5a2d8738bff3eb27d3c67
diff --git a/libc/arch-arm64/bionic/setjmp.S b/libc/arch-arm64/bionic/setjmp.S
index c408998..e94e5f4 100644
--- a/libc/arch-arm64/bionic/setjmp.S
+++ b/libc/arch-arm64/bionic/setjmp.S
@@ -114,6 +114,9 @@
.cfi_rel_offset x0, 0
.cfi_rel_offset x30, 8
+ // Commit SME's ZA lazy save. Note that the call preserves x1.
+ bl __arm_za_disable
+
// Get the cookie and store it along with the signal flag.
mov x0, x1
bl __bionic_setjmp_cookie_get
@@ -183,6 +186,17 @@
// void siglongjmp(sigjmp_buf env, int value);
ENTRY_WEAK_FOR_NATIVE_BRIDGE(siglongjmp)
+ // First of all, disable SME's ZA, so that it does not interfere
+ // with anything else. Note that __arm_za_disable is guaranteed to
+ // preserve x0 and x1.
+ str x30, [sp, #-16]!
+ .cfi_adjust_cfa_offset 16
+ .cfi_rel_offset x30, 0
+ bl __arm_za_disable
+ ldr x30, [sp], #16
+ .cfi_adjust_cfa_offset -16
+ .cfi_restore x30
+
// Check the checksum before doing anything.
m_calculate_checksum x12, x0, x2
ldr x2, [x0, #(_JB_CHECKSUM * 8)]
diff --git a/tests/setjmp_test.cpp b/tests/setjmp_test.cpp
index 9469285..836aadc 100644
--- a/tests/setjmp_test.cpp
+++ b/tests/setjmp_test.cpp
@@ -18,6 +18,7 @@
#include <setjmp.h>
#include <stdlib.h>
+#include <sys/auxv.h>
#include <sys/syscall.h>
#include <unistd.h>
@@ -364,3 +365,42 @@
GTEST_SKIP() << "tests uses functions not in glibc";
#endif
}
+
+#if defined(__aarch64__)
+TEST(setjmp, sigsetjmp_sme) {
+ if (!(getauxval(AT_HWCAP2) & HWCAP2_SME)) {
+ GTEST_SKIP() << "SME is not enabled on device.";
+ }
+
+ uint64_t svcr, za_state;
+ sigjmp_buf jb;
+ __asm__ __volatile__(".arch_extension sme; smstart za");
+ sigsetjmp(jb, 0);
+ __asm__ __volatile__(".arch_extension sme; mrs %0, SVCR" : "=r"(svcr));
+ __asm__ __volatile__(".arch_extension sme; smstop za"); // Turn ZA off anyway.
+ za_state = svcr & 0x2UL;
+ ASSERT_EQ(0UL, za_state);
+}
+
+TEST(setjmp, siglongjmp_sme) {
+ if (!(getauxval(AT_HWCAP2) & HWCAP2_SME)) {
+ GTEST_SKIP() << "SME is not enabled on device.";
+ }
+
+ uint64_t svcr, za_state;
+ int value;
+ sigjmp_buf jb;
+ if ((value = sigsetjmp(jb, 0)) == 0) {
+ __asm__ __volatile__(".arch_extension sme; smstart za");
+ siglongjmp(jb, 789);
+ __asm__ __volatile__(".arch_extension sme; smstop za");
+ FAIL(); // Unreachable.
+ } else {
+ __asm__ __volatile__(".arch_extension sme; mrs %0, SVCR" : "=r"(svcr));
+ __asm__ __volatile__(".arch_extension sme; smstop za"); // Turn ZA off anyway.
+ za_state = svcr & 0x2UL;
+ ASSERT_EQ(789, value);
+ ASSERT_EQ(0UL, za_state);
+ }
+}
+#endif
diff --git a/tests/signal_test.cpp b/tests/signal_test.cpp
index f8bfcef..27f5c6c 100644
--- a/tests/signal_test.cpp
+++ b/tests/signal_test.cpp
@@ -16,6 +16,7 @@
#include <errno.h>
#include <signal.h>
+#include <sys/auxv.h>
#include <sys/cdefs.h>
#include <sys/syscall.h>
#include <sys/types.h>
@@ -1070,3 +1071,35 @@
GTEST_SKIP() << "our old glibc doesn't have str2sig";
#endif
}
+
+#if defined(__aarch64__)
+__attribute__((target("arch=armv9+sme"))) __arm_new("za") static void FunctionUsingZA() {
+ raise(SIGUSR1);
+}
+
+TEST(signal, sme_tpidr2_clear) {
+ // When using SME, on entering a signal handler the kernel should clear TPIDR2_EL0, but this was
+ // not always correctly done. This tests checks if the kernel correctly clears it or not.
+ if (!(getauxval(AT_HWCAP2) & HWCAP2_SME)) {
+ GTEST_SKIP() << "SME is not enabled on device.";
+ }
+
+ static uint64_t tpidr2 = 0;
+ struct sigaction handler = {};
+ handler.sa_sigaction = [](int, siginfo_t*, void*) {
+ uint64_t zero = 0;
+ __asm__ __volatile__(".arch_extension sme; mrs %0, TPIDR2_EL0" : "=r"(tpidr2));
+ __asm__ __volatile__(".arch_extension sme; msr TPIDR2_EL0, %0" : : "r"(zero)); // Clear TPIDR2.
+ };
+ handler.sa_flags = SA_SIGINFO;
+
+ ASSERT_EQ(0, sigaction(SIGUSR1, &handler, nullptr));
+
+ FunctionUsingZA();
+
+ ASSERT_EQ(0x0UL, tpidr2)
+ << "Broken kernel! TPIDR2_EL0 was not null in the signal handler! "
+ << "Please make sure the following patch has been applied to the kernel: "
+ << "https://lore.kernel.org/linux-arm-kernel/20250417190113.3778111-1-mark.rutland@arm.com/";
+}
+#endif