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Sat, 18 Nov 2023 05:14:30 +0000 (UTC) From: Nathan Lynch via B4 Relay Date: Fri, 17 Nov 2023 23:14:25 -0600 Subject: [PATCH v4 07/13] powerpc/rtas: Warn if per-function lock isn't held MIME-Version: 1.0 Message-Id: <20231117-papr-sys_rtas-vs-lockdown-v4-7-b794d8cb8502@linux.ibm.com> References: <20231117-papr-sys_rtas-vs-lockdown-v4-0-b794d8cb8502@linux.ibm.com> In-Reply-To: <20231117-papr-sys_rtas-vs-lockdown-v4-0-b794d8cb8502@linux.ibm.com> To: Michael Ellerman , Nicholas Piggin X-Mailer: b4 0.12.4 X-Developer-Signature: v=1; a=ed25519-sha256; t=1700284468; l=1868; i=nathanl@linux.ibm.com; s=20230817; h=from:subject:message-id; bh=1NvPkcThP74+hpb/mqIyTlBIckWGXrqZhMZPxMBQGJ4=; b=42j3AAUduDUa+lq1rIUrfCsRGcfg25iIr3Ii6etXZYk+rPRU6QkUDQo9TL6UlHmq54WHIEcO3 82vAtuZ+srnBQh2ssEWagtVAzJ/KtF0+6OE9TTh/PpMUyHY2mKTsfdF X-Developer-Key: i=nathanl@linux.ibm.com; a=ed25519; pk=jPDF44RvT+9DGFOH3NGoIu1xN9dF+82pjdpnKjXfoJ0= X-Endpoint-Received: by B4 Relay for nathanl@linux.ibm.com/20230817 with auth_id=78 X-Original-From: Nathan Lynch X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: nathanl@linux.ibm.com Cc: Nathan Lynch , tyreld@linux.ibm.com, =?utf-8?q?Mi?= =?utf-8?q?chal_Such=C3=A1nek?= , linuxppc-dev@lists.ozlabs.org, gcwilson@linux.ibm.com Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Nathan Lynch If the function descriptor has a populated lock member, then callers are required to hold it across calls. Now that the firmware activation sequence is appropriately guarded, we can warn when the requirement isn't satisfied. __do_enter_rtas_trace() gets reorganized a bit as a result of performing the function descriptor lookup unconditionally now. Signed-off-by: Nathan Lynch Reviewed-by: Aneesh Kumar K.V (IBM) --- arch/powerpc/kernel/rtas.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index e38ba05ad613..deb6289fcf9c 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -685,28 +685,25 @@ static void __do_enter_rtas(struct rtas_args *args) static void __do_enter_rtas_trace(struct rtas_args *args) { - const char *name = NULL; + struct rtas_function *func = rtas_token_to_function(be32_to_cpu(args->token)); - if (args == &rtas_args) - lockdep_assert_held(&rtas_lock); /* - * If the tracepoints that consume the function name aren't - * active, avoid the lookup. + * If there is a per-function lock, it must be held by the + * caller. */ - if ((trace_rtas_input_enabled() || trace_rtas_output_enabled())) { - const s32 token = be32_to_cpu(args->token); - const struct rtas_function *func = rtas_token_to_function(token); + if (func->lock) + WARN_ON(!mutex_is_locked(func->lock)); - name = func->name; - } + if (args == &rtas_args) + lockdep_assert_held(&rtas_lock); - trace_rtas_input(args, name); + trace_rtas_input(args, func->name); trace_rtas_ll_entry(args); __do_enter_rtas(args); trace_rtas_ll_exit(args); - trace_rtas_output(args, name); + trace_rtas_output(args, func->name); } static void do_enter_rtas(struct rtas_args *args)