On 2024-12-26 21:35, Dmitry V. Levin wrote:
On Thu, Dec 26, 2024 at 06:52:52PM +0800, Celeste Liu wrote:
This test checks that orig_a0 allows a syscall argument to be modified, and that changing a0 does not change the syscall argument.
Co-developed-by: Quan Zhou zhouquan@iscas.ac.cn Signed-off-by: Quan Zhou zhouquan@iscas.ac.cn Co-developed-by: Charlie Jenkins charlie@rivosinc.com Signed-off-by: Charlie Jenkins charlie@rivosinc.com Reviewed-by: Björn Töpel bjorn@rivosinc.com Signed-off-by: Celeste Liu uwu@coelacanthus.name
[...]
diff --git a/tools/testing/selftests/riscv/abi/ptrace.c b/tools/testing/selftests/riscv/abi/ptrace.c new file mode 100644 index 0000000000000000000000000000000000000000..023695352215bb5de3f91c1a6f5ea3b4f9373ff9 --- /dev/null +++ b/tools/testing/selftests/riscv/abi/ptrace.c
[...]
- if (ptrace(PTRACE_GET_SYSCALL_INFO, pid, PTRACE_SYSCALL_INFO_ENTRY, &syscall_info_entry))
perr_and_exit("failed to get syscall info of entry\n");- result->orig_a0 = syscall_info_entry->entry.args[0];
- if (ptrace(PTRACE_GET_SYSCALL_INFO, pid, PTRACE_SYSCALL_INFO_EXIT, &syscall_info_exit))
perr_and_exit("failed to get syscall info of exit\n");- result->a0 = syscall_info_exit->exit.rval;
I'm sorry but this is not how PTRACE_GET_SYSCALL_INFO should be used.
PTRACE_GET_SYSCALL_INFO operation takes a pointer and a size, and in this example instead of size you pass constants 1 and 2, which essentially means that both syscall_info_entry->entry.args[0] and syscall_info_exit->exit.rval are not going to be assigned and would just contain some garbage from the stack.
Also, PTRACE_GET_SYSCALL_INFO operation returns the number of bytes available to be written by the kernel, which is always nonzero on any PTRACE_GET_SYSCALL_INFO-capable kernel. In other words, this example will always end up with perr_and_exit() call.
I wonder how this test was tested before the submission.
Oops... It seems I forget sync the code to test board so it runs with the old code... The code is completely not tested... I'm so sorry for my mistake.
I will correct it and test it carefully later...