On 2025-01-15 17:14, Andrew Jones wrote:
> 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 <zhouq...@iscas.ac.cn>
>> Signed-off-by: Quan Zhou <zhouq...@iscas.ac.cn>
>> Co-developed-by: Charlie Jenkins <char...@rivosinc.com>
>> Signed-off-by: Charlie Jenkins <char...@rivosinc.com>
>> Reviewed-by: Björn Töpel <bj...@rivosinc.com>
>> Signed-off-by: Celeste Liu <u...@coelacanthus.name>
>> ---
>> 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 <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 <linux/ptrace.h>
>> +#include <asm/ptrace.h>
>> +
>> +#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.
Agreed. But it may be better to be a separate patchset
so we can change those definition in different selftests
one pass.
>
>> +
>> +
>> +#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?
The purpose of the test is to ensure that the ORIG_A0_MODIFY operation
will not affect the a0 register (So it will not be our A0_NEW). But there
is a problem with the comment. It is written for some old wrong code.
I will correct the comment.
>
>> +
>> + /* 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
