[PATCH v2 08/12] powerpc/pseries: limit machine check stack to 4GB
Nicholas Piggin
npiggin at gmail.com
Wed Mar 25 21:34:06 AEDT 2020
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 <npiggin at gmail.com>
---
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
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