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[166.137.160.39]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2c7e57ce2e9sm446262a91.33.2024.06.19.19.55.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jun 2024 19:55:05 -0700 (PDT) Date: Wed, 19 Jun 2024 19:55:01 -0700 From: Charlie Jenkins To: zhouquan@iscas.ac.cn Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, oleg@redhat.com, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, andy.chiu@sifive.com, shuah@kernel.org Subject: Re: [RFC PATCH 2/2] riscv: selftests: Add a ptrace test to check a0 of restarted syscall Message-ID: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jun 19, 2024 at 10:01:47AM +0800, zhouquan@iscas.ac.cn wrote: > From: Quan Zhou > > 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. I don't quite follow what the goal of this test is. With orig_a0 being added to the previous patch for ptrace, a more constrained test could ensure that this value is respected. > > 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 > --- > 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 $(ARCH),riscv)) > -RISCV_SUBTARGETS ?= hwprobe vector mm sigreturn > +RISCV_SUBTARGETS ?= hwprobe vector mm sigreturn abi > else > RISCV_SUBTARGETS := > endif > diff --git a/tools/testing/selftests/riscv/abi/.gitignore b/tools/testing/selftests/riscv/abi/.gitignore > new file mode 100644 > index 000000000000..e1e00ffb9db9 > --- /dev/null > +++ b/tools/testing/selftests/riscv/abi/.gitignore > @@ -0,0 +1 @@ > +abi The gitignore should contain a list of all of the generated binaries that should be ignored. Can you put ptrace_restart_syscall in here instead of abi? > diff --git a/tools/testing/selftests/riscv/abi/Makefile b/tools/testing/selftests/riscv/abi/Makefile > new file mode 100644 > index 000000000000..634fa7de74e6 > --- /dev/null > +++ b/tools/testing/selftests/riscv/abi/Makefile > @@ -0,0 +1,12 @@ > +# SPDX-License-Identifier: GPL-2.0 > +# Copyright (C) 2021 ARM Limited > +# Originally tools/testing/arm64/abi/Makefile > + > +CFLAGS += -I$(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 > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#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); How does the value end up being 5? - Charlie > +} > + > +TEST_HARNESS_MAIN > -- > 2.34.1 >