Messages in this thread | | | From | Mathieu Malaterre <> | Date | Wed, 5 Jun 2019 13:32:39 +0200 | Subject | Re: [PATCH] powerpc/32s: fix booting with CONFIG_PPC_EARLY_DEBUG_BOOTX |
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On Mon, Jun 3, 2019 at 3:00 PM Christophe Leroy <christophe.leroy@c-s.fr> wrote: > > When booting through OF, setup_disp_bat() does nothing because > disp_BAT are not set. By change, it used to work because BOOTX > buffer is mapped 1:1 at address 0x81000000 by the bootloader, and > btext_setup_display() sets virt addr same as phys addr. > > But since commit 215b823707ce ("powerpc/32s: set up an early static > hash table for KASAN."), a temporary page table overrides the > bootloader mapping. > > This 0x81000000 is also problematic with the newly implemented > Kernel Userspace Access Protection (KUAP) because it is within user > address space. > > This patch fixes those issues by properly setting disp_BAT through > a call to btext_prepare_BAT(), allowing setup_disp_bat() to > properly setup BAT3 for early bootx screen buffer access. > > Reported-by: Mathieu Malaterre <malat@debian.org> > Fixes: 215b823707ce ("powerpc/32s: set up an early static hash table for KASAN.") > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
The patch below does fix the symptoms I reported. Tested with CONFIG_KASAN=n :
Tested-by: Mathieu Malaterre <malat@debian.org>
Thanks !
> --- > arch/powerpc/include/asm/btext.h | 4 ++++ > arch/powerpc/kernel/prom_init.c | 1 + > arch/powerpc/kernel/prom_init_check.sh | 2 +- > 3 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/btext.h b/arch/powerpc/include/asm/btext.h > index 3ffad030393c..461b0f193864 100644 > --- a/arch/powerpc/include/asm/btext.h > +++ b/arch/powerpc/include/asm/btext.h > @@ -13,7 +13,11 @@ extern void btext_update_display(unsigned long phys, int width, int height, > int depth, int pitch); > extern void btext_setup_display(int width, int height, int depth, int pitch, > unsigned long address); > +#ifdef CONFIG_PPC32 > extern void btext_prepare_BAT(void); > +#else > +static inline void btext_prepare_BAT(void) { } > +#endif > extern void btext_map(void); > extern void btext_unmap(void); > > diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c > index 3555cad7bdde..ed446b7ea164 100644 > --- a/arch/powerpc/kernel/prom_init.c > +++ b/arch/powerpc/kernel/prom_init.c > @@ -2336,6 +2336,7 @@ static void __init prom_check_displays(void) > prom_printf("W=%d H=%d LB=%d addr=0x%x\n", > width, height, pitch, addr); > btext_setup_display(width, height, 8, pitch, addr); > + btext_prepare_BAT(); > } > #endif /* CONFIG_PPC_EARLY_DEBUG_BOOTX */ > } > diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh > index 518d416971c1..160bef0d553d 100644 > --- a/arch/powerpc/kernel/prom_init_check.sh > +++ b/arch/powerpc/kernel/prom_init_check.sh > @@ -24,7 +24,7 @@ fi > WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush > _end enter_prom $MEM_FUNCS reloc_offset __secondary_hold > __secondary_hold_acknowledge __secondary_hold_spinloop __start > -logo_linux_clut224 > +logo_linux_clut224 btext_prepare_BAT > reloc_got2 kernstart_addr memstart_addr linux_banner _stext > __prom_init_toc_start __prom_init_toc_end btext_setup_display TOC." > > -- > 2.13.3 >
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