Re: [PATCH] powerpc/chrp: Fix enter_rtas() with CONFIG_VMAP_STACK
From: Michael Neuling <hidden>
Date: 2020-02-16 22:40:11
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lkml
On Fri, 2020-02-14 at 08:33 +0000, Christophe Leroy wrote:
With CONFIG_VMAP_STACK, data MMU has to be enabled to read data on the stack.
Can you describe what goes wrong without this? Some oops message? rtas blows up? Get corrupt data? Also can you say what you're actually doing (ie turning on MSR[DR])
quoted hunk ↗ jump to hunk
Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/kernel/entry_32.S | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 0713daa651d9..bc056d906b51 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S@@ -1354,12 +1354,17 @@ _GLOBAL(enter_rtas) mtspr SPRN_SRR0,r8 mtspr SPRN_SRR1,r9 RFI -1: tophys(r9,r1) +1: tophys_novmstack r9, r1 +#ifdef CONFIG_VMAP_STACK + li r0, MSR_KERNEL & ~MSR_IR /* can take DTLB miss */
You're potentially turning on more than MSR DR here. This should be clear in the commit message.
+ mtmsr r0 + isync +#endif lwz r8,INT_FRAME_SIZE+4(r9) /* get return address */ lwz r9,8(r9) /* original msr value */ addi r1,r1,INT_FRAME_SIZE li r0,0 - tophys(r7, r2) + tophys_novmstack r7, r2 stw r0, THREAD + RTAS_SP(r7) mtspr SPRN_SRR0,r8 mtspr SPRN_SRR1,r9