Hi Ard, On Thu, Jan 6, 2022 at 8:27 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > The resume from suspend code switches to the ID map so it can enable the > MMU. On !LPAE configurations, the ID map carries its own copy of the > kernel VA range, but this is not kept in sync with swapper_pg_dir, and > so it may lack the mapping of the kernel mode stack if CONFIG_VMAP_STACK > is enabled. > > So let's switch to swapper_pg_dir right after re-enabling the MMU on > such configurations. This avoids a crash on resume observed on various > platforms [0]. > > [0] https://lore.kernel.org/linux-arm-kernel/20211122092816.2865873-8-ardb@xxxxxxxxxx/ > > Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> > Cc: Jon Hunter <jonathanh@xxxxxxxxxx> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> Thanks for your patch! This fixes s2ram on r8a7791/koelsch (dual Cortex-A15) with shmobile_defconfig. S2ram on sh73a0/kzm9g (dual Cortex-A9) works as before. Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> > --- > Please test with the Kconfig patch [9177/1] reverted. > > arch/arm/kernel/sleep.S | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S > index b062b3738bc6..6217ef90feb0 100644 > --- a/arch/arm/kernel/sleep.S > +++ b/arch/arm/kernel/sleep.S > @@ -119,6 +119,13 @@ ENTRY(cpu_resume_mmu) > ENDPROC(cpu_resume_mmu) > .popsection > cpu_resume_after_mmu: > +#if defined(CONFIG_VMAP_STACK) && !defined(CONFIG_ARM_LPAE) > + @ Before using the vmap'ed stack, we have to switch to swapper_pg_dir > + @ as the ID map does not cover the vmalloc region. > + mrc p15, 0, ip, c2, c0, 1 @ read TTBR1 > + mcr p15, 0, ip, c2, c0, 0 @ set TTBR0 > + isb > +#endif > bl cpu_init @ restore the und/abt/irq banked regs > mov r0, #0 @ return zero on success > ldmfd sp!, {r4 - r11, pc} Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
