#ifdef __powerpc64__
#ifdef CONFIG_PPC_BOOK3S
-#define TRAP_FLAGS_MASK 0
-#define TRAP(regs) ((regs)->trap)
+#define TRAP_FLAGS_MASK 0x10
+#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK)
#define FULL_REGS(regs) true
#define SET_FULL_REGS(regs) do { } while (0)
#else
-#define TRAP_FLAGS_MASK 0x1
-#define TRAP(regs) ((regs)->trap & ~0x1)
+#define TRAP_FLAGS_MASK 0x11
+#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK)
#define FULL_REGS(regs) (((regs)->trap & 1) == 0)
#define SET_FULL_REGS(regs) ((regs)->trap |= 1)
#endif
* On 4xx we use the next bit to indicate whether the exception
* is a critical exception (1 means it is).
*/
-#define TRAP_FLAGS_MASK 0xF
-#define TRAP(regs) ((regs)->trap & ~0xF)
+#define TRAP_FLAGS_MASK 0x1F
+#define TRAP(regs) ((regs)->trap & ~TRAP_FLAGS_MASK)
#define FULL_REGS(regs) (((regs)->trap & 1) == 0)
#define SET_FULL_REGS(regs) ((regs)->trap |= 1)
#define IS_CRITICAL_EXC(regs) (((regs)->trap & 2) != 0)
return TRAP(regs) == 0xc00;
}
+static inline bool trap_norestart(struct pt_regs *regs)
+{
+ return regs->trap & 0x10;
+}
+
+static inline void set_trap_norestart(struct pt_regs *regs)
+{
+ regs->trap |= 0x10;
+}
+
#define arch_has_single_step() (1)
#ifndef CONFIG_BOOK3S_601
#define arch_has_block_step() (true)
err |= __get_user(regs->link, &sc->gp_regs[PT_LNK]);
err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]);
err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]);
- /* skip SOFTE */
- regs->trap = 0;
+ /* Don't allow userspace to set SOFTE */
+ set_trap_norestart(regs);
err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);
&sc->gp_regs[PT_XER]);
err |= __get_user(tsk->thread.ckpt_regs.ccr,
&sc->gp_regs[PT_CCR]);
-
- /* Don't allow userspace to set the trap value */
- regs->trap = 0;
-
+ /* Don't allow userspace to set SOFTE */
+ set_trap_norestart(regs);
/* These regs are not checkpointed; they can go in 'regs'. */
err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Test that a syscall does not get restarted twice, handled by trap_norestart()
+ *
+ * Based on Al's description, and a test for the bug fixed in this commit:
+ *
+ * commit 9a81c16b527528ad307843be5571111aa8d35a80
+ * Author: Al Viro <viro@zeniv.linux.org.uk>
+ * Date: Mon Sep 20 21:48:57 2010 +0100
+ *
+ * powerpc: fix double syscall restarts
+ *
+ * Make sigreturn zero regs->trap, make do_signal() do the same on all
+ * paths. As it is, signal interrupting e.g. read() from fd 512 (==
+ * ERESTARTSYS) with another signal getting unblocked when the first
+ * handler finishes will lead to restart one insn earlier than it ought
+ * to. Same for multiple signals with in-kernel handlers interrupting
+ * that sucker at the same time. Same for multiple signals of any kind
+ * interrupting that sucker on 64bit...
+ */
+#define _GNU_SOURCE
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <signal.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "utils.h"
+
+static void SIGUSR1_handler(int sig)
+{
+ kill(getpid(), SIGUSR2);
+ /*
+ * SIGUSR2 is blocked until the handler exits, at which point it will
+ * be raised again and think there is a restart to be done because the
+ * pending restarted syscall has 512 (ERESTARTSYS) in r3. The second
+ * restart will retreat NIP another 4 bytes to fail case branch.
+ */
+}
+
+static void SIGUSR2_handler(int sig)
+{
+}
+
+static ssize_t raw_read(int fd, void *buf, size_t count)
+{
+ register long nr asm("r0") = __NR_read;
+ register long _fd asm("r3") = fd;
+ register void *_buf asm("r4") = buf;
+ register size_t _count asm("r5") = count;
+
+ asm volatile(
+" b 0f \n"
+" b 1f \n"
+" 0: sc 0 \n"
+" bns 2f \n"
+" neg %0,%0 \n"
+" b 2f \n"
+" 1: \n"
+" li %0,%4 \n"
+" 2: \n"
+ : "+r"(_fd), "+r"(nr), "+r"(_buf), "+r"(_count)
+ : "i"(-ENOANO)
+ : "memory", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "ctr", "cr0");
+
+ if (_fd < 0) {
+ errno = -_fd;
+ _fd = -1;
+ }
+
+ return _fd;
+}
+
+#define DATA "test 123"
+#define DLEN (strlen(DATA)+1)
+
+int test_restart(void)
+{
+ int pipefd[2];
+ pid_t pid;
+ char buf[512];
+
+ if (pipe(pipefd) == -1) {
+ perror("pipe");
+ exit(EXIT_FAILURE);
+ }
+
+ pid = fork();
+ if (pid == -1) {
+ perror("fork");
+ exit(EXIT_FAILURE);
+ }
+
+ if (pid == 0) { /* Child reads from pipe */
+ struct sigaction act;
+ int fd;
+
+ memset(&act, 0, sizeof(act));
+ sigaddset(&act.sa_mask, SIGUSR2);
+ act.sa_handler = SIGUSR1_handler;
+ act.sa_flags = SA_RESTART;
+ if (sigaction(SIGUSR1, &act, NULL) == -1) {
+ perror("sigaction");
+ exit(EXIT_FAILURE);
+ }
+
+ memset(&act, 0, sizeof(act));
+ act.sa_handler = SIGUSR2_handler;
+ act.sa_flags = SA_RESTART;
+ if (sigaction(SIGUSR2, &act, NULL) == -1) {
+ perror("sigaction");
+ exit(EXIT_FAILURE);
+ }
+
+ /* Let's get ERESTARTSYS into r3 */
+ while ((fd = dup(pipefd[0])) != 512) {
+ if (fd == -1) {
+ perror("dup");
+ exit(EXIT_FAILURE);
+ }
+ }
+
+ if (raw_read(fd, buf, 512) == -1) {
+ if (errno == ENOANO) {
+ fprintf(stderr, "Double restart moved restart before sc instruction.\n");
+ _exit(EXIT_FAILURE);
+ }
+ perror("read");
+ exit(EXIT_FAILURE);
+ }
+
+ if (strncmp(buf, DATA, DLEN)) {
+ fprintf(stderr, "bad test string %s\n", buf);
+ exit(EXIT_FAILURE);
+ }
+
+ return 0;
+
+ } else {
+ int wstatus;
+
+ usleep(100000); /* Hack to get reader waiting */
+ kill(pid, SIGUSR1);
+ usleep(100000);
+ if (write(pipefd[1], DATA, DLEN) != DLEN) {
+ perror("write");
+ exit(EXIT_FAILURE);
+ }
+ close(pipefd[0]);
+ close(pipefd[1]);
+ if (wait(&wstatus) == -1) {
+ perror("wait");
+ exit(EXIT_FAILURE);
+ }
+ if (!WIFEXITED(wstatus)) {
+ fprintf(stderr, "child exited abnormally\n");
+ exit(EXIT_FAILURE);
+ }
+
+ FAIL_IF(WEXITSTATUS(wstatus) != EXIT_SUCCESS);
+
+ return 0;
+ }
+}
+
+int main(void)
+{
+ test_harness_set_timeout(10);
+ return test_harness(test_restart, "sig sys restart");
+}
projects / mirror_ubuntu-jammy-kernel.git / commitdiff