On 2025-01-10 11:34, Charlie Jenkins wrote:
On Thu, Dec 26, 2024 at 11:21:59PM +0800, Celeste Liu wrote:
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...
It would be great to get this into 6.14. Let me know if you would like any help!
v5 has been sent.
Sorry for delay. My test environment was broken yesterday so I have to spend time to repair it first...
https://lore.kernel.org/lkml/20250115-riscv-new-regset-v5-0-d0e6ec031a23@coe...
- Charlie