From: Quan Zhou <[email protected]> This test creates two processes: a tracer and a tracee. The tracer actively sends a SIGUSR1 signal in user mode to interrupt the read syscall being executed by the tracee. We will reset a0/orig_a0 and then observe the value of a0 held by the restarted read syscall.
Compared to the test program, a more common scenario is the use of the exece syscall, which sends a signal in the kernel path to restart the syscall. Signed-off-by: Quan Zhou <[email protected]> --- tools/testing/selftests/riscv/Makefile | 2 +- tools/testing/selftests/riscv/abi/.gitignore | 1 + tools/testing/selftests/riscv/abi/Makefile | 12 ++ .../riscv/abi/ptrace_restart_syscall.c | 148 ++++++++++++++++++ 4 files changed, 162 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/riscv/abi/.gitignore create mode 100644 tools/testing/selftests/riscv/abi/Makefile create mode 100644 tools/testing/selftests/riscv/abi/ptrace_restart_syscall.c diff --git a/tools/testing/selftests/riscv/Makefile b/tools/testing/selftests/riscv/Makefile index 7ce03d832b64..98541dc2f164 100644 --- a/tools/testing/selftests/riscv/Makefile +++ b/tools/testing/selftests/riscv/Makefile @@ -5,7 +5,7 @@ ARCH ?= $(shell uname -m 2>/dev/null || echo not) ifneq (,$(filter $(ARCH),riscv)) -RISCV_SUBTARGETS ?= hwprobe vector mm sigreturn +RISCV_SUBTARGETS ?= hwprobe vector mm sigreturn abi else RISCV_SUBTARGETS := endif diff --git a/tools/testing/selftests/riscv/abi/.gitignore b/tools/testing/selftests/riscv/abi/.gitignore new file mode 100644 index 000000000000..e1e00ffb9db9 --- /dev/null +++ b/tools/testing/selftests/riscv/abi/.gitignore @@ -0,0 +1 @@ +abi diff --git a/tools/testing/selftests/riscv/abi/Makefile b/tools/testing/selftests/riscv/abi/Makefile new file mode 100644 index 000000000000..634fa7de74e6 --- /dev/null +++ b/tools/testing/selftests/riscv/abi/Makefile @@ -0,0 +1,12 @@ +# SPDX-License-Identifier: GPL-2.0 +# Copyright (C) 2021 ARM Limited +# Originally tools/testing/arm64/abi/Makefile + +CFLAGS += -I$(top_srcdir)/tools/include + +TEST_GEN_PROGS := ptrace_restart_syscall + +include ../../lib.mk + +$(OUTPUT)/ptrace_restart_syscall: ptrace_restart_syscall.c + $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^ diff --git a/tools/testing/selftests/riscv/abi/ptrace_restart_syscall.c b/tools/testing/selftests/riscv/abi/ptrace_restart_syscall.c new file mode 100644 index 000000000000..3e25548cb95e --- /dev/null +++ b/tools/testing/selftests/riscv/abi/ptrace_restart_syscall.c @@ -0,0 +1,148 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <fcntl.h> +#include <signal.h> +#include <errno.h> +#include <sys/types.h> +#include <sys/ptrace.h> +#include <sys/stat.h> +#include <sys/user.h> +#include <sys/wait.h> +#include <sys/uio.h> +#include <linux/elf.h> +#include <linux/unistd.h> +#include <asm/ptrace.h> + +#include "../../kselftest_harness.h" + +#define ORIG_A0_AFTER_MODIFIED 0x5 +#define MODIFY_A0 0x01 +#define MODIFY_ORIG_A0 0x02 + +#define perr_and_exit(fmt, ...) do { \ + char buf[256]; \ + snprintf(buf, sizeof(buf), "%s:%d: " fmt ": %m\n", \ + __func__, __LINE__, ##__VA_ARGS__); \ + perror(buf); \ + exit(-1); \ +} while (0) + +static inline void resume_and_wait_tracee(pid_t pid, int flag) +{ + int status; + + if (ptrace(flag, pid, 0, 0)) + perr_and_exit("failed to resume the tracee %d", pid); + + if (waitpid(pid, &status, 0) != pid) + perr_and_exit("failed to wait for the tracee %d", pid); +} + +static void ptrace_restart_syscall(int opt, int *result) +{ + int status; + int p[2], fd_zero; + pid_t pid; + + struct user_regs_struct regs; + struct iovec iov = { + .iov_base = ®s, + .iov_len = sizeof(regs), + }; + + if (pipe(p)) + perr_and_exit("failed to create a pipe"); + + fd_zero = open("/dev/zero", O_RDONLY); + if (fd_zero < 0) + perr_and_exit("failed to open /dev/zero"); + + pid = fork(); + if (pid == 0) { + char c; + + /* Mark oneself being traced */ + if (ptrace(PTRACE_TRACEME, 0, 0, 0)) + perr_and_exit("failed to request for tracer to trace me"); + + kill(getpid(), SIGSTOP); + + if (read(p[0], &c, 1) != 1) + exit(1); + + exit(0); + } else if (pid < 0) + exit(1); + + if (waitpid(pid, &status, 0) != pid) + perr_and_exit("failed to wait for the tracee %d\n", pid); + + /* Resume the tracee until the next syscall */ + resume_and_wait_tracee(pid, PTRACE_SYSCALL); + + /* Deliver a signal to interrupt the syscall */ + kill(pid, SIGUSR1); + + /* The tracee stops at syscall exit */ + resume_and_wait_tracee(pid, PTRACE_SYSCALL); + + /* Check tracee orig_a0 before syscall restart */ + if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov)) + perr_and_exit("failed to get tracee registers"); + if (regs.orig_a0 != p[0]) + perr_and_exit("unexpected a0"); + + /* Modify a0/orig_a0 for the restarted syscall */ + switch (opt) { + case MODIFY_A0: + regs.a0 = fd_zero; + break; + case MODIFY_ORIG_A0: + regs.orig_a0 = fd_zero; + break; + } + + if (ptrace(PTRACE_SETREGSET, pid, NT_PRSTATUS, &iov)) + perr_and_exit("failed to set tracee registers"); + + /* Ignore SIGUSR1 signal */ + resume_and_wait_tracee(pid, PTRACE_SYSCALL); + + /* Stop at the entry point of the restarted syscall */ + resume_and_wait_tracee(pid, PTRACE_SYSCALL); + + /* Now, check regs.a0 of the restarted syscall */ + if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov)) + perr_and_exit("failed to get tracee registers"); + *result = regs.a0; + + /* Resume the tracee */ + ptrace(PTRACE_CONT, pid, 0, 0); + if (waitpid(pid, &status, 0) != pid) + perr_and_exit("failed to wait for the tracee"); +} + +TEST(ptrace_modify_a0) +{ + int result; + + ptrace_restart_syscall(MODIFY_A0, &result); + + /* The tracer's modification of a0 cannot affect the restarted tracee */ + EXPECT_NE(ORIG_A0_AFTER_MODIFIED, result); +} + +TEST(ptrace_modify_orig_a0) +{ + int result; + + ptrace_restart_syscall(MODIFY_ORIG_A0, &result); + + /* The tracer must modify orig_a0 to actually change the tracee's a0 */ + EXPECT_EQ(ORIG_A0_AFTER_MODIFIED, result); +} + +TEST_HARNESS_MAIN -- 2.34.1
