Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :
This allows rtas_args to be put on the machine check stack, which avoids a lot of complications with re-entrancy deadlocks. Reviewed-by: Mahesh Salgaonkar <[email protected]> Signed-off-by: Nicholas Piggin <[email protected]>
Reviewed-by: Christophe Leroy <[email protected]>
--- arch/powerpc/kernel/setup_64.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 438a9befce41..defe05b6b7a9 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -709,7 +709,7 @@ void __init exc_lvl_early_init(void) */ void __init emergency_stack_init(void) { - u64 limit; + u64 limit, mce_limit; unsigned int i;/*@@ -726,7 +726,16 @@ void __init emergency_stack_init(void) * initialized in kernel/irq.c. These are initialized here in order * to have emergency stacks available as early as possible. */ - limit = min(ppc64_bolted_size(), ppc64_rma_size); + limit = mce_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. + */ + if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > SZ_4G) + mce_limit = SZ_4G;for_each_possible_cpu(i) {paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE; @@ -736,7 +745,7 @@ 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 } }
