tests/tcg/aarch64: Add gcspushm

Validate successful and trapped executions of GCSPUSHM, GCSPOPM.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20251008215613.300150-73-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

tests/tcg/aarch64/Makefile.target

@@ -76,7 +76,7 @@ $(SME_TESTS): CFLAGS += $(CROSS_AS_HAS_ARMV9_SME)
 endif
 
 # GCS Tests
-GCS_TESTS += gcsstr
+GCS_TESTS += gcsstr gcspushm
 AARCH64_TESTS += $(GCS_TESTS)
 $(GCS_TESTS): gcs.h
 

tests/tcg/aarch64/gcspushm.c

@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "gcs.h"
+
+
+#define GCSPUSHM  "sys #3, c7, c7, #0, %[push]"
+#define GCSPOPM   "sysl %[pop], #3, c7, c7, #1"
+
+static void test_sigsegv(int sig, siginfo_t *info, void *vuc)
+{
+    ucontext_t *uc = vuc;
+    uint64_t inst_sigsegv;
+
+    __asm__("adr %0, inst_sigsegv" : "=r"(inst_sigsegv));
+    assert(uc->uc_mcontext.pc == inst_sigsegv);
+    assert(info->si_code == SEGV_CPERR);
+    /* TODO: Dig for ESR and verify syndrome. */
+    uc->uc_mcontext.pc += 4;
+}
+
+static void test_sigill(int sig, siginfo_t *info, void *vuc)
+{
+    ucontext_t *uc = vuc;
+    uint64_t inst_sigill;
+
+    __asm__("adr %0, inst_sigill" : "=r"(inst_sigill));
+    assert(uc->uc_mcontext.pc == inst_sigill);
+    assert(info->si_code == ILL_ILLOPC);
+    uc->uc_mcontext.pc += 4;
+}
+
+int main()
+{
+    struct sigaction sa = { .sa_flags = SA_SIGINFO };
+    uint64_t old, new;
+
+    sa.sa_sigaction = test_sigsegv;
+    if (sigaction(SIGSEGV, &sa, NULL) < 0) {
+        perror("sigaction");
+        exit(1);
+    }
+
+    sa.sa_sigaction = test_sigill;
+    if (sigaction(SIGILL, &sa, NULL) < 0) {
+        perror("sigaction");
+        exit(1);
+    }
+
+    /* Pushm is disabled -- SIGILL via EC_SYSTEMREGISTERTRAP */
+    asm volatile("inst_sigill:\t" GCSPUSHM
+                 : : [push] "r" (1));
+
+    enable_gcs(PR_SHADOW_STACK_PUSH);
+
+    /* Valid value -- low 2 bits clear */
+    old = 0xdeadbeeffeedcaec;
+    asm volatile(GCSPUSHM "\n\t" GCSPOPM
+                 : [pop] "=r" (new)
+                 : [push] "r" (old)
+                 : "memory");
+    assert(old == new);
+
+    /* Invalid value -- SIGSEGV via EC_GCS */
+    asm volatile(GCSPUSHM "\n"
+                 "inst_sigsegv:\t" GCSPOPM
+                 : [pop] "=r" (new)
+                 : [push] "r" (1)
+                 : "memory");
+
+    exit(0);
+}