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[2001:1ae9:1c2:4c00:20f:c6b4:1e57:7965]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-437c74e3b97sm15973265e9.32.2025.01.15.01.14.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jan 2025 01:14:03 -0800 (PST) Date: Wed, 15 Jan 2025 10:14:02 +0100 From: Andrew Jones To: Celeste Liu Cc: Oleg Nesterov , Paul Walmsley , Palmer Dabbelt , Eric Biederman , Kees Cook , Shuah Khan , Albert Ou , Alexandre Ghiti , "Dmitry V. Levin" , Andrea Bolognani , =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= , Thomas Gleixner , Ron Economos , Charlie Jenkins , Quan Zhou , Felix Yan , Ruizhe Pan , Guo Ren , Yao Zi , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= Subject: Re: [PATCH v5 2/2] riscv: selftests: Add a ptrace test to verify a0 and orig_a0 access Message-ID: <20250115-28c95808502d43f84b3fe0a6@orel> References: <20250115-riscv-new-regset-v5-0-d0e6ec031a23@coelacanthus.name> <20250115-riscv-new-regset-v5-2-d0e6ec031a23@coelacanthus.name> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250115-riscv-new-regset-v5-2-d0e6ec031a23@coelacanthus.name> On Wed, Jan 15, 2025 at 04:24:59AM +0800, Celeste Liu wrote: > This test checks that orig_a0 and a0 can be modified and accessed > independently. > > Co-developed-by: Quan Zhou > Signed-off-by: Quan Zhou > Co-developed-by: Charlie Jenkins > Signed-off-by: Charlie Jenkins > Reviewed-by: Björn Töpel > Signed-off-by: Celeste Liu > --- > tools/testing/selftests/riscv/abi/.gitignore | 1 + > tools/testing/selftests/riscv/abi/Makefile | 6 +- > tools/testing/selftests/riscv/abi/ptrace.c | 201 +++++++++++++++++++++++++++ > 3 files changed, 207 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/riscv/abi/.gitignore b/tools/testing/selftests/riscv/abi/.gitignore > index b38358f91c4d2240ae64892871d9ca98bda1ae58..378c605919a3b3d58eec2701eb7af430cfe315d6 100644 > --- a/tools/testing/selftests/riscv/abi/.gitignore > +++ b/tools/testing/selftests/riscv/abi/.gitignore > @@ -1 +1,2 @@ > pointer_masking > +ptrace > diff --git a/tools/testing/selftests/riscv/abi/Makefile b/tools/testing/selftests/riscv/abi/Makefile > index ed82ff9c664e7eb3f760cbab81fb957ff72579c5..359a082c88a401883fb3776b35e4dacf69beaaaa 100644 > --- a/tools/testing/selftests/riscv/abi/Makefile > +++ b/tools/testing/selftests/riscv/abi/Makefile > @@ -1,10 +1,14 @@ > # SPDX-License-Identifier: GPL-2.0 > > CFLAGS += -I$(top_srcdir)/tools/include > +CFLAGS += $(KHDR_INCLUDES) > > -TEST_GEN_PROGS := pointer_masking > +TEST_GEN_PROGS := pointer_masking ptrace > > include ../../lib.mk > > $(OUTPUT)/pointer_masking: pointer_masking.c > $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^ > + > +$(OUTPUT)/ptrace: ptrace.c > + $(CC) -static -o$@ $(CFLAGS) $(LDFLAGS) $^ > diff --git a/tools/testing/selftests/riscv/abi/ptrace.c b/tools/testing/selftests/riscv/abi/ptrace.c > new file mode 100644 > index 0000000000000000000000000000000000000000..f1a0458adccdd040bfaa350e2e8d98b1ef34c0ad > --- /dev/null > +++ b/tools/testing/selftests/riscv/abi/ptrace.c > @@ -0,0 +1,201 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include "../../kselftest_harness.h" > + > +#ifndef sizeof_field > +#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER)) > +#endif > +#ifndef offsetofend > +#define offsetofend(TYPE, MEMBER) \ > + (offsetof(TYPE, MEMBER) + sizeof_field(TYPE, MEMBER)) > +#endif I think this is the sixth test to define these. We should copy include/linux/stddef.h into tools/include. We already have tools/include/uapi/linux/stddef.h with __struct_group and __DECLARE_FLEX_ARRAY, so I think it should just work. > + > + > +#define ORIG_A0_MODIFY 0x01 > +#define A0_MODIFY 0x02 > +#define A0_OLD 0xbadbeefbeeff > +#define A0_NEW 0xffeebfeebdab > + > + > +struct a0_regs { > + __s64 orig_a0; > + __u64 a0; > +}; > + > +#define perr_and_exit(fmt, ...) \ > + ({ \ > + char buf[256]; \ > + snprintf(buf, sizeof(buf), "%s:%d:" fmt ": %m\n", \ > + __func__, __LINE__, ##__VA_ARGS__); \ > + ksft_exit_fail_perror(buf); \ > + }) > + > +static void ptrace_test(int opt, struct a0_regs result[]) > +{ > + int status; > + long rc; > + pid_t pid; > + struct user_regs_struct regs; > + struct iovec iov = { > + .iov_base = ®s, > + .iov_len = sizeof(regs), > + }; > + > + unsigned long orig_a0; > + struct iovec a0_iov = { > + .iov_base = &orig_a0, > + .iov_len = sizeof(orig_a0), > + }; > + struct ptrace_syscall_info syscall_info = { > + .op = 0xff, > + }; > + const unsigned int expected_sci_entry_size = > + offsetofend(struct ptrace_syscall_info, entry.args); > + const unsigned int expected_sci_exit_size = > + offsetofend(struct ptrace_syscall_info, exit.is_error); > + > + pid = fork(); > + if (pid == 0) { > + /* Mark oneself being traced */ > + long val = ptrace(PTRACE_TRACEME, 0, 0, 0); > + > + if (val < 0) > + perr_and_exit("failed to request for tracer to trace me: %ld", val); > + > + kill(getpid(), SIGSTOP); > + > + /* Perform chdir syscall that will be intercepted */ > + syscall(__NR_chdir, A0_OLD); > + > + exit(0); > + } > + > + if (pid < 0) > + ksft_exit_fail_perror("failed to fork"); > + > + for (int i = 0; i < 3; i++) { > + if (waitpid(pid, &status, 0) != pid) > + perr_and_exit("failed to wait for the tracee %d", pid); > + if (WIFSTOPPED(status)) { > + switch (WSTOPSIG(status)) { > + case SIGSTOP: > + if (ptrace(PTRACE_SETOPTIONS, pid, 0, PTRACE_O_TRACESYSGOOD) < 0) > + perr_and_exit("failed to set PTRACE_O_TRACESYSGOOD"); > + break; > + case SIGTRAP|0x80: > + /* Modify twice so GET_SYSCALL_INFO get modified a0 and orig_a0 */ > + if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov)) > + perr_and_exit("failed to get tracee registers"); > + if (ptrace(PTRACE_GETREGSET, pid, NT_RISCV_ORIG_A0, &a0_iov)) > + perr_and_exit("failed to get tracee registers"); > + > + /* Modify a0/orig_a0 for the syscall */ > + switch (opt) { > + case A0_MODIFY: > + regs.a0 = A0_NEW; > + break; > + case ORIG_A0_MODIFY: > + orig_a0 = A0_NEW; > + break; > + } > + > + if (ptrace(PTRACE_SETREGSET, pid, NT_PRSTATUS, &iov)) > + perr_and_exit("failed to set tracee registers"); > + if (ptrace(PTRACE_SETREGSET, pid, NT_RISCV_ORIG_A0, &a0_iov)) > + perr_and_exit("failed to set tracee registers"); > + switch (i) { > + case 1: > + /* Stop at the beginning of syscall */ > + rc = ptrace(PTRACE_GET_SYSCALL_INFO, pid, > + sizeof(syscall_info), &syscall_info); > + if (rc < 0) > + perr_and_exit("failed to get syscall info of entry"); > + if (rc < expected_sci_entry_size > + || syscall_info.op != PTRACE_SYSCALL_INFO_ENTRY) > + perr_and_exit("stop position of entry mismatched"); > + result[0].orig_a0 = syscall_info.entry.args[0]; > + break; > + > + case 2: > + /* Stop at the end of syscall */ > + rc = ptrace(PTRACE_GET_SYSCALL_INFO, pid, > + sizeof(syscall_info), &syscall_info); > + if (rc < 0) > + perr_and_exit("failed to get syscall info of entry"); > + if (rc < expected_sci_exit_size > + || syscall_info.op != PTRACE_SYSCALL_INFO_EXIT) > + perr_and_exit("stop position of exit mismatched"); > + result[0].a0 = syscall_info.exit.rval; > + > + if (ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &iov)) > + perr_and_exit("failed to get tracee registers"); > + result[1].a0 = regs.a0; > + if (ptrace(PTRACE_GETREGSET, pid, NT_RISCV_ORIG_A0, > + &a0_iov)) > + perr_and_exit("failed to get tracee registers"); > + result[1].orig_a0 = orig_a0; > + } > + } > + if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0) > + perr_and_exit("failed to resume tracee"); > + } > + } > + > + /* 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_access_a0) > +{ > + struct a0_regs result[2]; > + > + ptrace_test(A0_MODIFY, result); > + > + /* Verify PTRACE_SETREGSET */ > + /* The modification of a0 cannot affect the first argument of the syscall */ > + EXPECT_EQ(A0_OLD, result[0].orig_a0); > + EXPECT_EQ(A0_NEW, result[0].a0); > + > + /* Verify PTRACE_GETREGSET */ > + EXPECT_EQ(result[1].orig_a0, result[0].orig_a0); > + EXPECT_EQ(result[1].a0, result[0].a0); > +} > + > +TEST(ptrace_access_orig_a0) > +{ > + struct a0_regs result[2]; > + > + ptrace_test(ORIG_A0_MODIFY, result); > + > + /* Verify PTRACE_SETREGSET */ > + /* Only modify orig_a0 to change the first argument of the syscall */ > + EXPECT_EQ(A0_NEW, result[0].orig_a0); > + /* a0 will keep default value, orig_a0 or -ENOSYS, depends on internal. */ > + EXPECT_NE(A0_NEW, result[0].a0); I don't understand this test. Why don't we know what to expect? Also, the comment says orig_a0 is an option for the value, but then we don't expect it to be A0_NEW, even though we expect orig_a0 to be A0_NEW? > + > + /* Verify PTRACE_GETREGSET */ > + EXPECT_EQ(result[1].orig_a0, result[0].orig_a0); > + EXPECT_EQ(result[1].a0, result[0].a0); > +} > + > +TEST_HARNESS_MAIN > > -- > 2.48.0 > Other than the two comments/questions, this test looks great. Thanks, drew