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authorThomas Gleixner <tglx@linutronix.de>2021-06-11 15:03:16 +0200
committerIngo Molnar <mingo@kernel.org>2021-06-24 08:49:03 +0200
commit7f049fbdd57f6ea71dc741d903c19c73b2f70950 (patch)
tree5b11e726fd368def34a736cfa73511ac95ded45e /arch/x86
parent13311e74253fe64329390df80bed3f07314ddd61 (diff)
perf/x86/intel/lbr: Zero the xstate buffer on allocation
XRSTORS requires a valid xstate buffer to work correctly. XSAVES does not guarantee to write a fully valid buffer according to the SDM: "XSAVES does not write to any parts of the XSAVE header other than the XSTATE_BV and XCOMP_BV fields." XRSTORS triggers a #GP: "If bytes 63:16 of the XSAVE header are not all zero." It's dubious at best how this can work at all when the buffer is not zeroed before use. Allocate the buffers with __GFP_ZERO to prevent XRSTORS failure. Fixes: ce711ea3cab9 ("perf/x86/intel/lbr: Support XSAVES/XRSTORS for LBR context switch") Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/87wnr0wo2z.ffs@nanos.tec.linutronix.de
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/events/intel/lbr.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 4409d2cccfda..e8453de7a964 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -731,7 +731,8 @@ void reserve_lbr_buffers(void)
if (!kmem_cache || cpuc->lbr_xsave)
continue;
- cpuc->lbr_xsave = kmem_cache_alloc_node(kmem_cache, GFP_KERNEL,
+ cpuc->lbr_xsave = kmem_cache_alloc_node(kmem_cache,
+ GFP_KERNEL | __GFP_ZERO,
cpu_to_node(cpu));
}
}