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Fri, 23 Oct 2026 07:37:15 +0000 (GMT) Received: from Narayanas-MacBook-Pro.ibm.com (unknown [9.39.18.128]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 23 Oct 2026 07:37:15 +0000 (GMT) From: Narayana Murty N To: Mahesh J Salgaonkar , Madhavan Srinivasan , "Oliver O'Halloran" , Timothy Pearson , Alex Williamson Cc: sourabhjain@linux.ibm.com, Michael Ellerman , Nicholas Piggin , Christophe Leroy , Ritesh Harjani , Shrikanth Hegde , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, sbhat@linux.ibm.com, harshpb@linux.ibm.com Subject: [PATCH v6 1/5] powerpc/rtas: Handle ibm,open-errinjct return format Date: Fri, 23 Oct 2026 13:06:38 +0530 Message-ID: <20261023073642.59657-2-nnmlinux@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261023073642.59657-1-nnmlinux@linux.ibm.com> References: <20261023073642.59657-1-nnmlinux@linux.ibm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDIzMDAyOCBTYWx0ZWRfXxtCj2DreJae1 3zzW0AIXUolQXMRHsY/fPB91Aoy44yxLkYl/h7Md3g3VkE8906SNh2mtaLic4qXKXME2iNYs/Mh VqLkL2Co4WpMRAU8+xNXoaU38pr6/Uo= X-Proofpoint-GUID: reXkLwSboGh_AYKg22Y6QOGW2lhnkAUI X-Proofpoint-ORIG-GUID: XEh_9PZYJCijpVl2kfepy1_XUwnBV1pO X-Authority-Analysis: v=2.4 cv=UOBIjyfy c=1 sm=1 tr=0 ts=6adb0eb4 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=660iZSQnnn4A:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=1mVJ_uiqAAAA:8 a=VnNF1IyMAAAA:8 a=UsokGn5mh7P9jOUuuDIA:9 a=h67g7WpEjx8dfGT80pje:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDIzMDAyOCBTYWx0ZWRfX/U602YaRnAk8 8rfKMQpMfvgnLX+t2d5KfJg9kQGadL3ucF+yqdAX8Q57L65xtEgt1HSK7bba44J6hoi+6/rebcY IJRZ6NQPWrefV+ZzqUlOfPVNDWn9mqn+ZGhoTis6Zphf1U18tH6v71bS2Hb6D9bjUOnte9PLAlv EDS1ICunqEoHDw8M21CQvJg9BZqGj3RhB6RE/XJ0oiJHA1WBYks5ifkUVnqqWgHpaLkX/nwuIrL AUZ6Maco7S0amSjGi3K41sXBJssUeiMxwjoXhx38QjaBg16HbOIM/W/egQ7icbPyndjhrLU9Er4 G3O//90Ig5F/jd10FT/0awHYGfliYi7luHr58wn8wnWCTbs+eNQGRas9rLJoNvc9/WeREdNaOOt aAIgONktOkrPiBUZufXGIguSO7zwt0ATsjq08DdyYrg/jZJmbLtIg0Yc32yV98ipeNxAa2nR5Ds SLtJ+syA1DHv5QvCWrg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-10-23_02,2026-10-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 clxscore=1015 suspectscore=0 spamscore=0 priorityscore=1501 lowpriorityscore=0 adultscore=0 impostorscore=0 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610190000 definitions=main-2610230028 ibm,open-errinjct uses a non-standard RTAS return layout: rets[0] = session token (output parameter) rets[1] = status code Unlike all other RTAS functions which use: rets[0] = status code rets[1..] = output parameters Add rtas_token_is_open_errinjct() to identify this call, and rtas_status_from_args() to extract status from the correct position. Add an early guard in rtas_call() that rejects ibm,open-errinjct invocations where nret < 2, since reading rets[1] would be out of bounds. This is a kernel-side call-convention error, so -EINVAL is returned rather than an RTAS firmware status code: if (rtas_token_is_open_errinjct(token) && nret < 2) { WARN_ON_ONCE(1); return -EINVAL; } Adjust the output-copy loop so that for ibm,open-errinjct: return value = rets[1] (status) outputs[0] = rets[0] (session token) For all other functions the existing convention is preserved: return value = rets[0] (status) outputs[0..] = rets[1..] (non-status outputs) Move the "/* A -1 return code... */" comment immediately before the ret == -1 check so it documents the check it guards. Also fix sys_rtas() last-error status detection: add the same early nret < 2 validation at the syscall boundary (returning -EINVAL) to avoid entering RTAS with an invalid ibm,open-errinjct return layout. After that guard, use rtas_status_from_args() to obtain the RTAS status for last-error handling. The prominent user librtas already passes nret = 2 for this function as required by PAPR, so well-formed callers are unaffected. Reference: OpenPOWER PAPR documentation https://files.openpower.foundation/s/XFgfMaqLMD5Bcm8 Signed-off-by: Narayana Murty N --- arch/powerpc/kernel/rtas.c | 78 +++++++++++++++++++++++++++++++++----- 1 file changed, 69 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 8d81c1e7a8db..38f3d08d4228 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -1117,6 +1117,28 @@ static bool token_is_restricted_errinjct(s32 token) token == rtas_function_token(RTAS_FN_IBM_ERRINJCT); } +/* + * ibm,open-errinjct uses a non-standard return layout: + * rets[0] = session token (output parameter) + * rets[1] = status code + * + * All other RTAS functions use the standard layout: + * rets[0] = status code + * rets[1..] = output parameters + */ +static inline bool rtas_token_is_open_errinjct(int token) +{ + return token == rtas_function_token(RTAS_FN_IBM_OPEN_ERRINJCT); +} + +static int rtas_status_from_args(int token, struct rtas_args *args, int nret) +{ + if (rtas_token_is_open_errinjct(token)) + return be32_to_cpu(args->rets[1]); + + return nret > 0 ? be32_to_cpu(args->rets[0]) : 0; +} + /** * rtas_call() - Invoke an RTAS firmware function. * @token: Identifies the function being invoked. @@ -1198,6 +1220,16 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) return -1; } + /* + * ibm,open-errinjct returns rets[0]=session_token, rets[1]=status. + * We need nret >= 2 to read status from rets[1]. Reject early if + * the caller forgot to account for the extra return cell. + */ + if (rtas_token_is_open_errinjct(token) && nret < 2) { + WARN_ON_ONCE(1); + return -EINVAL; + } + if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) { WARN_ON_ONCE(1); return -1; @@ -1213,15 +1245,33 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) va_rtas_call_unlocked(args, token, nargs, nret, list); va_end(list); + ret = rtas_status_from_args(token, args, nret); + /* A -1 return code indicates that the last command couldn't - be completed due to a hardware error. */ - if (be32_to_cpu(args->rets[0]) == -1) + * be completed due to a hardware error. + */ + if (ret == -1) buff_copy = __fetch_rtas_last_error(NULL); - if (nret > 1 && outputs != NULL) - for (i = 0; i < nret-1; ++i) - outputs[i] = be32_to_cpu(args->rets[i + 1]); - ret = (nret > 0) ? be32_to_cpu(args->rets[0]) : 0; + /* + * Copy non-status outputs to the caller's buffer. + * + * For ibm,open-errinjct the layout is: + * rets[0] = session token -> outputs[0] + * rets[1] = status (returned, not copied) + * + * For all other RTAS functions: + * rets[0] = status (returned, not copied) + * rets[1..nret-1] -> outputs[0..nret-2] + */ + if (outputs) { + if (rtas_token_is_open_errinjct(token)) { + outputs[0] = be32_to_cpu(args->rets[0]); + } else if (nret > 1) { + for (i = 0; i < nret - 1; ++i) + outputs[i] = be32_to_cpu(args->rets[i + 1]); + } + } lockdep_unpin_lock(&rtas_lock, cookie); raw_spin_unlock_irqrestore(&rtas_lock, flags); @@ -1896,6 +1946,14 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) if (block_rtas_call(func, nargs, &args)) return -EINVAL; + /* + * ibm,open-errinjct places status at rets[1]; reject calls with + * fewer than 2 return cells before entering RTAS, since reading + * rets[1] for the -1 sentinel would be out of bounds. + */ + if (rtas_token_is_open_errinjct(token) && nret < 2) + return -EINVAL; + if (token_is_restricted_errinjct(token)) { int err; @@ -1942,9 +2000,11 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) do_enter_rtas(&rtas_args); args = rtas_args; - /* A -1 return code indicates that the last command couldn't - be completed due to a hardware error. */ - if (be32_to_cpu(args.rets[0]) == -1) + /* + * A -1 return code indicates that the last command couldn't + * be completed due to a hardware error. + */ + if (rtas_status_from_args(token, &args, nret) == -1) errbuf = __fetch_rtas_last_error(buff_copy); lockdep_unpin_lock(&rtas_lock, cookie); -- 2.54.0