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[14.202.190.183]) by smtp.gmail.com with ESMTPSA id b9sm16549701pgi.75.2020.03.25.03.35.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 03:35:12 -0700 (PDT) From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2 08/12] powerpc/pseries: limit machine check stack to 4GB Date: Wed, 25 Mar 2020 20:34:06 +1000 Message-Id: <20200325103410.157573-9-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20200325103410.157573-1-npiggin@gmail.com> References: <20200325103410.157573-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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: , Cc: Mahesh Salgaonkar , Ganesh Goudar , Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" This allows rtas_args to be put on the machine check stack, which avoids a lot of complications with re-entrancy deadlocks. Signed-off-by: Nicholas Piggin --- arch/powerpc/kernel/setup_64.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 3bf03666ee09..ca1041f8a578 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -695,6 +695,9 @@ void __init exc_lvl_early_init(void) void __init emergency_stack_init(void) { u64 limit; +#ifdef CONFIG_PPC_BOOK3S_64 + u64 mce_limit; +#endif unsigned int i; /* @@ -713,6 +716,16 @@ void __init emergency_stack_init(void) */ limit = min(ppc64_bolted_size(), ppc64_rma_size); + /* + * Machine check on pseries calls rtas, but can't use the static + * rtas_args due to a machine check hitting while the lock is held. + * rtas args have to be under 4GB, so the machine check stack is + * limited to 4GB so args can be put on stack. + */ + mce_limit = limit; + if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > 4UL*1024*1024*1024) + mce_limit = 4UL*1024*1024*1024; + for_each_possible_cpu(i) { paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE; @@ -721,7 +734,7 @@ void __init emergency_stack_init(void) paca_ptrs[i]->nmi_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE; /* emergency stack for machine check exception handling. */ - paca_ptrs[i]->mc_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE; + paca_ptrs[i]->mc_emergency_sp = alloc_stack(mce_limit, i) + THREAD_SIZE; #endif } } -- 2.23.0