[PATCH] riscv: entry: always initialize regs->a0 to -ENOSYS

[Celeste Liu]

On 2024-06-27 22:08, Björn Töpel wrote:

> Celeste Liu <coelacanthushex at gmail.com> writes:
> 
>> Otherwise when the tracer changes syscall number to -1, the kernel fails
>> to initialize a0 with -ENOSYS and subsequently fails to return the error
>> code of the failed syscall to userspace. For example, it will break
>> strace syscall tampering.
>>
>> Fixes: 52449c17bdd1 ("riscv: entry: set a0 = -ENOSYS only when syscall != -1")
>> Cc: stable at vger.kernel.org
>> Signed-off-by: Celeste Liu <CoelacanthusHex at gmail.com>
> 
> Reported-by: "Dmitry V. Levin" <ldv at strace.io>
> Reviewed-by: Björn Töpel <bjorn at rivosinc.com>

Patch v2 has been sent.