[PATCH v2] powerpc/pseries: Avoid using addr_to_pfn in realmode
From: Ganesh Goudar <hidden>
Date: 2020-07-09 16:41:35
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
When an UE or memory error exception is encountered the MCE handler tries to find the pfn using addr_to_pfn() which takes effective address as an argument, later pfn is used to poison the page where memory error occurred, recent rework in this area made addr_to_pfn to run in realmode, which can be fatal as it may try to access memory outside RMO region. To fix this use addr_to_pfn after switching to virtual mode. Signed-off-by: Ganesh Goudar <redacted> --- V2: Leave bare metal code and save_mce_event as is. --- arch/powerpc/platforms/pseries/ras.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c
index f3736fcd98fc..def875815e92 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c@@ -610,16 +610,8 @@ static int mce_handle_error(struct pt_regs *regs, struct rtas_error_log *errp) if (mce_log->sub_err_type & UE_EFFECTIVE_ADDR_PROVIDED) eaddr = be64_to_cpu(mce_log->effective_address); - if (mce_log->sub_err_type & UE_LOGICAL_ADDR_PROVIDED) { + if (mce_log->sub_err_type & UE_LOGICAL_ADDR_PROVIDED) paddr = be64_to_cpu(mce_log->logical_address); - } else if (mce_log->sub_err_type & UE_EFFECTIVE_ADDR_PROVIDED) { - unsigned long pfn; - - pfn = addr_to_pfn(regs, eaddr); - if (pfn != ULONG_MAX) - paddr = pfn << PAGE_SHIFT; - } - break; case MC_ERROR_TYPE_SLB: mce_err.error_type = MCE_ERROR_TYPE_SLB;
@@ -725,6 +717,16 @@ static int mce_handle_error(struct pt_regs *regs, struct rtas_error_log *errp) * SLB multihit is done by now. */ mtmsr(mfmsr() | MSR_IR | MSR_DR); + + /* Use addr_to_pfn after switching to virtual mode */ + if (!paddr && error_type == MC_ERROR_TYPE_UE && + mce_log->sub_err_type & UE_EFFECTIVE_ADDR_PROVIDED) { + unsigned long pfn; + + pfn = addr_to_pfn(regs, eaddr); + if (pfn != ULONG_MAX) + paddr = pfn << PAGE_SHIFT; + } save_mce_event(regs, disposition == RTAS_DISP_FULLY_RECOVERED, &mce_err, regs->nip, eaddr, paddr);
--
2.17.2