From bfe3b1945d5e0531103b3d4ab3a367a1a156d99a Mon Sep 17 00:00:00 2001 From: Athira Rajeev Date: Fri, 17 Jul 2020 10:38:21 -0400 Subject: [PATCH] powerpc/perf: Ignore the BHRB kernel address filtering for P10 Commit bb19af816025 ("powerpc/perf: Prevent kernel address leak to userspace via BHRB buffer") added a check in bhrb_read() to filter the kernel address from BHRB buffer. This patch modified it to avoid that check for PowerISA v3.1 based processors, since PowerISA v3.1 allows only MSR[PR]=1 address to be written to BHRB buffer. Signed-off-by: Athira Rajeev Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1594996707-3727-10-git-send-email-atrajeev@linux.vnet.ibm.com --- arch/powerpc/perf/core-book3s.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 6bffffa..e31629f 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -470,8 +470,11 @@ static void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events * * addresses at this point. Check the privileges before * exporting it to userspace (avoid exposure of regions * where we could have speculative execution) + * Incase of ISA v3.1, BHRB will capture only user-space + * addresses, hence include a check before filtering code */ - if (is_kernel_addr(addr) && perf_allow_kernel(&event->attr) != 0) + if (!(ppmu->flags & PPMU_ARCH_31) && + is_kernel_addr(addr) && perf_allow_kernel(&event->attr) != 0) continue; /* Branches are read most recent first (ie. mfbhrb 0 is -- 2.7.4