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Levin" Cc: Christophe Leroy , Oleg Nesterov , Eugene Syromyatnikov , Mike Frysinger , Renzo Davoli , Davide Berardi , strace-devel@lists.strace.io, Madhavan Srinivasan , Nicholas Piggin , Naveen N Rao , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/7] powerpc: properly negate error in syscall_set_return_value() In-Reply-To: References: <20250113171054.GA589@strace.io> <6558110c-c2cb-4aa3-9472-b3496f71ebb8@csgroup.eu> <20250114170400.GB11820@strace.io> <20250123182815.GA20994@strace.io> <20250123234321.GA23582@strace.io> Date: Sat, 25 Jan 2025 23:18:06 +1100 Message-ID: <87ikq3jddt.fsf@mpe.ellerman.id.au> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Alexey Gladkov writes: > ... > I'm not a powerpc expert but shouldn't be used regs->gpr[3] via a > regs_return_value() in system_call_exception() ? Yes I agree. > notrace long system_call_exception(struct pt_regs *regs, unsigned long r0) > { > ... > r0 = do_syscall_trace_enter(regs); > if (unlikely(r0 >= NR_syscalls)) > return regs->gpr[3]; This is the case where we're expecting the r3 value to be a negative error code, to match the in-kernel semantics. But after this change it would be a positive error value. It is probably harmless with the current code structure, but that's just luck. cheers