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Diffstat (limited to 'gdb/testsuite/gdb.arch/aarch64-gcs.c')
| -rw-r--r-- | gdb/testsuite/gdb.arch/aarch64-gcs.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/gdb/testsuite/gdb.arch/aarch64-gcs.c b/gdb/testsuite/gdb.arch/aarch64-gcs.c new file mode 100644 index 0000000..9eb2e9e --- /dev/null +++ b/gdb/testsuite/gdb.arch/aarch64-gcs.c @@ -0,0 +1,180 @@ +/* This test program is part of GDB, the GNU debugger. + + Copyright 2025 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +#include <stdio.h> +#include <stdlib.h> +#include <signal.h> +#include <sys/auxv.h> +#include <sys/syscall.h> +#include <linux/prctl.h> + +/* Feature check for Guarded Control Stack. */ +#ifndef HWCAP_GCS +#define HWCAP_GCS (1ULL << 32) +#endif + +#ifndef PR_GET_SHADOW_STACK_STATUS +#define PR_GET_SHADOW_STACK_STATUS 74 +#define PR_SET_SHADOW_STACK_STATUS 75 +#define PR_SHADOW_STACK_ENABLE (1UL << 0) +#endif + +/* We need to use a macro to call prctl because after GCS is enabled, it's not + possible to return from the function which enabled it. This is because the + return address of the calling function isn't on the GCS. */ +#define my_syscall2(num, arg1, arg2) \ + ({ \ + register long _num __asm__("x8") = (num); \ + register long _arg1 __asm__("x0") = (long)(arg1); \ + register long _arg2 __asm__("x1") = (long)(arg2); \ + register long _arg3 __asm__("x2") = 0; \ + register long _arg4 __asm__("x3") = 0; \ + register long _arg5 __asm__("x4") = 0; \ + \ + __asm__ volatile ("svc #0\n" \ + : "=r"(_arg1) \ + : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \ + "r"(_arg5), "r"(_num) \ + : "memory", "cc"); \ + _arg1; \ + }) + +#define get_gcspr(void) \ + ({ \ + unsigned long *gcspr; \ + \ + /* Get GCSPR_EL0. */ \ + asm volatile ("mrs %0, S3_3_C2_C5_1" : "=r"(gcspr) : : "cc"); \ + \ + gcspr; \ + }) + +static unsigned long *handler_gcspr = 0; + +static void +handler (int sig) +{ + handler_gcspr = get_gcspr (); +} + +static int __attribute__ ((unused)) +called_from_gdb (int val) +{ + return val + 1; +} + +/* Corrupt the return address to see if GDB will report a SIGSEGV with the + expected $_siginfo.si_code. */ +static void __attribute__ ((noinline)) +normal_function2 (void) +{ + /* x30 holds the return address. */ + register unsigned long x30 __asm__("x30") __attribute__ ((unused)); + + /* Cause a GCS exception. */ + x30 = 0xbadc0ffee; + /* Use explicit ret so that we can verify that a SIGSEGV was generated + exactly on the return instruction. */ + __asm__ volatile ("ret\n"); +} + +static inline void __attribute__ ((__always_inline__)) +inline_function2 (void) +{ + normal_function2 (); +} + +static void __attribute__ ((noinline)) +normal_function1 (void) +{ + inline_function2 (); +} + +/* First in a sequence of inline and normal functions, to test GDB + backtrace. */ +static inline void __attribute__ ((__always_inline__)) +inline_function1 (void) +{ + normal_function1 (); +} + +/* Trivial function, just so that GDB can test return with wrong GCSPR. */ +static void __attribute__ ((noinline)) +normal_function0 (void) +{ + /* Use explicit ret so that we can verify that a SIGSEGV was generated + exactly on the return instruction. */ + __asm__ volatile ("ret\n"); +} + +int +main (void) +{ + if (!(getauxval (AT_HWCAP) & HWCAP_GCS)) + { + fprintf (stderr, "GCS support not found in AT_HWCAP\n"); + return EXIT_FAILURE; + } + + /* Force shadow stacks on, our tests *should* be fine with or + without libc support and with or without this having ended + up tagged for GCS and enabled by the dynamic linker. We + can't use the libc prctl() function since we can't return + from enabling the stack. Also lock GCS if not already + locked so we can test behaviour when it's locked. */ + unsigned long gcs_mode; + int ret = my_syscall2 (__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &gcs_mode); + if (ret) + { + fprintf (stderr, "Failed to read GCS state: %d\n", ret); + return EXIT_FAILURE; + } + + if (!(gcs_mode & PR_SHADOW_STACK_ENABLE)) + { + gcs_mode = PR_SHADOW_STACK_ENABLE; + ret = my_syscall2 (__NR_prctl, PR_SET_SHADOW_STACK_STATUS, gcs_mode); + if (ret) + { + fprintf (stderr, "Failed to configure GCS: %d\n", ret); + return EXIT_FAILURE; + } + } + + /* Regular function call. */ + normal_function0 (); + + /* This is used by GDB. */ + __attribute__((unused)) unsigned long *gcspr = get_gcspr (); + + struct sigaction act = { 0 }; + + act.sa_handler = &handler; /* Break here. */ + if (sigaction (SIGUSR1, &act, NULL) == -1) + { + perror ("sigaction"); + exit (EXIT_FAILURE); + } + + raise (SIGUSR1); + +/* Call sequence of inline and normal functions, to test GDB backtrace. */ + inline_function1 (); + + /* Avoid returning, in case libc doesn't understand GCS. */ + exit (EXIT_SUCCESS); +} |