Messages in this thread | | | From | Rob Herring <> | Date | Thu, 1 Sep 2022 08:21:02 -0500 | Subject | Re: [PATCH] ARM: mmu: fix access to illegal address when using earlycon & memblock=debug |
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On Thu, Sep 1, 2022 at 7:54 AM Victor Hassan <victor@allwinnertech.com> wrote: > > > > On 2022/8/31 20:37, Victor Hassan wrote: > > On 8/31/2022 7:52 PM, Marek Szyprowski wrote: > >> Hi Victor, > >> > >> On 16.03.2022 03:33, Victor Hassan wrote: > >>> earlycon uses fixmap to create a memory map, > >>> So we need to close earlycon before closing fixmap, > >>> otherwise printk will access illegal addresses.
How? Due to recent changes in how printk and the consoles work or just because create_mapping() can print? In the latter case, the only variable input is the phys address. I think most if not all prints cannot occur.
> >>> After creating a new memory map, we open earlycon again. > >>> > >>> Signed-off-by: Victor Hassan <victor@allwinnertech.com> > >> > >> This patch landed in linux next-20220831 as commit a76886d117cb ("ARM: > >> 9223/1: mmu: fix access to illegal address when using earlycon & > >> memblock=debug"). Unfortunately it breaks booting of all my test boards > >> which *do not* use earlycon. It can be easily reproduced even with QEMU. > >> > >> With kernel compiled from multi_v7_defconfig the following setup boots: > >> > >> $ qemu-system-arm -nographic -kernel arch/arm/boot/zImage -append > >> "console=ttyAMA0 earlycon" -M virt -smp 2 -m 512 > >> > >> while this one doesn't: > >> > >> $ qemu-system-arm -nographic -kernel arch/arm/boot/zImage -append > >> "console=ttyAMA0" -M virt -smp 2 -m 512 > >> > >> > >>> --- > >>> arch/arm/mm/mmu.c | 7 +++++++ > >>> 1 file changed, 7 insertions(+) > >>> > >>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c > >>> index 274e4f73fd33..f3511f07a7d0 100644 > >>> --- a/arch/arm/mm/mmu.c > >>> +++ b/arch/arm/mm/mmu.c > >>> @@ -14,6 +14,7 @@ > >>> #include <linux/fs.h> > >>> #include <linux/vmalloc.h> > >>> #include <linux/sizes.h> > >>> +#include <linux/console.h> > >>> #include <asm/cp15.h> > >>> #include <asm/cputype.h> > >>> @@ -1695,6 +1696,9 @@ static void __init early_fixmap_shutdown(void) > >>> pmd_clear(fixmap_pmd(va)); > >>> local_flush_tlb_kernel_page(va); > >>> +#ifdef CONFIG_FIX_EARLYCON_MEM > >>> + console_stop(console_drivers); > >>> +#endif > >>> for (i = 0; i < __end_of_permanent_fixed_addresses; i++) { > >>> pte_t *pte; > >>> struct map_desc map; > >>> @@ -1713,6 +1717,9 @@ static void __init early_fixmap_shutdown(void) > >>> create_mapping(&map); > >>> } > >>> +#ifdef CONFIG_FIX_EARLYCON_MEM > >>> + console_start(console_drivers); > >>> +#endif > >>> } > >>> /* > >> > >> Best regards > > > > Dear Marek, > > Thank you for the notice. I'll figure it out and feed back to you as > > soon as possible. > > > > Regards, > > Victor > > Hi Marek, > > Sorry, didn't take into account that console_drivers is NULL when > earlycon is not used. > > Here is the patch-v2. Please review: > > diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c > index a49f0b9..a240f38 100644 > --- a/arch/arm/mm/mmu.c > +++ b/arch/arm/mm/mmu.c > @@ -14,6 +14,7 @@ > #include <linux/fs.h> > #include <linux/vmalloc.h> > #include <linux/sizes.h> > +#include <linux/console.h> > > #include <asm/cp15.h> > #include <asm/cputype.h> > @@ -1730,6 +1731,10 @@ > pmd_clear(fixmap_pmd(va)); > local_flush_tlb_kernel_page(va); > > +#ifdef CONFIG_FIX_EARLYCON_MEM
This is always true for CONFIG_MMU and this file is only built for CONFIG_MMU. So you don't need it.
> + if (console_drivers) > + console_stop(console_drivers);
console_drivers is a list, so you are only stopping the 1st one. Couldn't console_lock() be used here?
Also, this should be before pmd_clear().
> +#endif > for (i = 0; i < __end_of_permanent_fixed_addresses; i++) { > pte_t *pte; > struct map_desc map; > @@ -1748,6 +1753,10 @@ > > create_mapping(&map); > } > +#ifdef CONFIG_FIX_EARLYCON_MEM > + if (console_drivers) > + console_start(console_drivers); > +#endif > } > > BTW, should I resend the patch-v2 through the site > (https://www.armlinux.org.uk/developer/patches/add.php), or should I > send the patch-v2 through E-mail to Linux-Mainline? > > Thanks you. > > Regards, > Victor > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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