diff options
Diffstat (limited to 'tools/testing/selftests/x86/fsgsbase.c')
| -rw-r--r-- | tools/testing/selftests/x86/fsgsbase.c | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/tools/testing/selftests/x86/fsgsbase.c b/tools/testing/selftests/x86/fsgsbase.c index 15a329da59fa..757bdb218a66 100644 --- a/tools/testing/selftests/x86/fsgsbase.c +++ b/tools/testing/selftests/x86/fsgsbase.c @@ -442,6 +442,68 @@ static void test_unexpected_base(void) #define USER_REGS_OFFSET(r) offsetof(struct user_regs_struct, r) +static void test_ptrace_write_gs_read_base(void) +{ + int status; + pid_t child = fork(); + + if (child < 0) + err(1, "fork"); + + if (child == 0) { + printf("[RUN]\tPTRACE_POKE GS, read GSBASE back\n"); + + printf("[RUN]\tARCH_SET_GS to 1\n"); + if (syscall(SYS_arch_prctl, ARCH_SET_GS, 1) != 0) + err(1, "ARCH_SET_GS"); + + if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) + err(1, "PTRACE_TRACEME"); + + raise(SIGTRAP); + _exit(0); + } + + wait(&status); + + if (WSTOPSIG(status) == SIGTRAP) { + unsigned long base; + unsigned long gs_offset = USER_REGS_OFFSET(gs); + unsigned long base_offset = USER_REGS_OFFSET(gs_base); + + /* Read the initial base. It should be 1. */ + base = ptrace(PTRACE_PEEKUSER, child, base_offset, NULL); + if (base == 1) { + printf("[OK]\tGSBASE started at 1\n"); + } else { + nerrs++; + printf("[FAIL]\tGSBASE started at 0x%lx\n", base); + } + + printf("[RUN]\tSet GS = 0x7, read GSBASE\n"); + + /* Poke an LDT selector into GS. */ + if (ptrace(PTRACE_POKEUSER, child, gs_offset, 0x7) != 0) + err(1, "PTRACE_POKEUSER"); + + /* And read the base. */ + base = ptrace(PTRACE_PEEKUSER, child, base_offset, NULL); + + if (base == 0 || base == 1) { + printf("[OK]\tGSBASE reads as 0x%lx with invalid GS\n", base); + } else { + nerrs++; + printf("[FAIL]\tGSBASE=0x%lx (should be 0 or 1)\n", base); + } + } + + ptrace(PTRACE_CONT, child, NULL, NULL); + + wait(&status); + if (!WIFEXITED(status)) + printf("[WARN]\tChild didn't exit cleanly.\n"); +} + static void test_ptrace_write_gsbase(void) { int status; @@ -499,6 +561,9 @@ static void test_ptrace_write_gsbase(void) END: ptrace(PTRACE_CONT, child, NULL, NULL); + wait(&status); + if (!WIFEXITED(status)) + printf("[WARN]\tChild didn't exit cleanly.\n"); } int main() @@ -508,6 +573,9 @@ int main() shared_scratch = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED, -1, 0); + /* Do these tests before we have an LDT. */ + test_ptrace_write_gs_read_base(); + /* Probe FSGSBASE */ sethandler(SIGILL, sigill, 0); if (sigsetjmp(jmpbuf, 1) == 0) { |