2020-02-14 06:53:24

by Christophe Leroy

Subject: [PATCH] powerpc/6xx: Fix power_save_ppc32_restore() with CONFIG_VMAP_STACK

power_save_ppc32_restore() is called during exception entry, before
re-enabling the MMU. It substracts KERNELBASE from the address
of nap_save_msscr0 to access it.

With CONFIG_VMAP_STACK enabled, data MMU translation has already been
re-enabled, so power_save_ppc32_restore() has to access
nap_save_msscr0 by its virtual address.

Reported-by: Larry Finger <[email protected]>
Signed-off-by: Christophe Leroy <[email protected]>
Fixes: cd08f109e262 ("powerpc/32s: Enable CONFIG_VMAP_STACK")
Tested-by: Larry Finger <[email protected]>
---
arch/powerpc/kernel/idle_6xx.S | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/arch/powerpc/kernel/idle_6xx.S b/arch/powerpc/kernel/idle_6xx.S
index 0ffdd18b9f26..433d97bea1f3 100644
--- a/arch/powerpc/kernel/idle_6xx.S
+++ b/arch/powerpc/kernel/idle_6xx.S
@@ -166,7 +166,11 @@ BEGIN_FTR_SECTION
mfspr r9,SPRN_HID0
andis. r9,r9,HID0_NAP@h
beq 1f
+#ifdef CONFIG_VMAP_STACK
+ addis r9, r11, nap_save_msscr0@ha
+#else
addis r9,r11,(nap_save_msscr0-KERNELBASE)@ha
+#endif
lwz r9,nap_save_msscr0@l(r9)
mtspr SPRN_MSSCR0, r9
sync
@@ -174,7 +178,11 @@ BEGIN_FTR_SECTION
1:
END_FTR_SECTION_IFSET(CPU_FTR_NAP_DISABLE_L2_PR)
BEGIN_FTR_SECTION
+#ifdef CONFIG_VMAP_STACK
+ addis r9, r11, nap_save_hid1@ha
+#else
addis r9,r11,(nap_save_hid1-KERNELBASE)@ha
+#endif
lwz r9,nap_save_hid1@l(r9)
mtspr SPRN_HID1, r9
END_FTR_SECTION_IFSET(CPU_FTR_DUAL_PLL_750FX)
--
2.25.0

2020-02-19 12:40:41

by Michael Ellerman

Subject: Re: [PATCH] powerpc/6xx: Fix power_save_ppc32_restore() with CONFIG_VMAP_STACK

On Fri, 2020-02-14 at 06:53:00 UTC, Christophe Leroy wrote:
> power_save_ppc32_restore() is called during exception entry, before
> re-enabling the MMU. It substracts KERNELBASE from the address
> of nap_save_msscr0 to access it.
>
> With CONFIG_VMAP_STACK enabled, data MMU translation has already been
> re-enabled, so power_save_ppc32_restore() has to access
> nap_save_msscr0 by its virtual address.
>
> Reported-by: Larry Finger <[email protected]>
> Signed-off-by: Christophe Leroy <[email protected]>
> Fixes: cd08f109e262 ("powerpc/32s: Enable CONFIG_VMAP_STACK")
> Tested-by: Larry Finger <[email protected]>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/477f3488a94e35380c82a7498d46f10fa5f3edd2

cheers