From: Roman Gushchin <guro@fb.com>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: <linux-mips@vger.kernel.org>, <rppt@kernel.org>,
<fancer.lancer@gmail.com>, <akpm@linux-foundation.org>,
<paul@crapouillou.net>,
Serge Semin <Sergey.Semin@baikalelectronics.ru>,
Kamal Dasu <kdasu.kdev@gmail.com>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Yanteng Si <siyanteng@loongson.cn>,
Huacai Chen <chenhuacai@kernel.org>,
"open list:BROADCOM BMIPS MIPS ARCHITECTURE"
<bcm-kernel-feedback-list@broadcom.com>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] MIPS: BMIPS: Reserve exception base to prevent corruption
Date: Tue, 2 Mar 2021 11:04:01 -0800 [thread overview]
Message-ID: <YD6MIcfsS3o53Kto@carbon.dhcp.thefacebook.com> (raw)
In-Reply-To: <20210302041940.3663823-1-f.fainelli@gmail.com>
On Mon, Mar 01, 2021 at 08:19:38PM -0800, Florian Fainelli wrote:
> BMIPS is one of the few platforms that do change the exception base.
> After commit 2dcb39645441 ("memblock: do not start bottom-up allocations
> with kernel_end") we started seeing BMIPS boards fail to boot with the
> built-in FDT being corrupted.
>
> Before the cited commit, early allocations would be in the [kernel_end,
> RAM_END] range, but after commit they would be within [RAM_START +
> PAGE_SIZE, RAM_END].
>
> The custom exception base handler that is installed by
> bmips_ebase_setup() done for BMIPS5000 CPUs ends-up trampling on the
> memory region allocated by unflatten_and_copy_device_tree() thus
> corrupting the FDT used by the kernel.
>
> To fix this, we need to perform an early reservation of the custom
> exception that is going to be installed and this needs to happen at
> plat_mem_setup() time to ensure that unflatten_and_copy_device_tree()
> finds a space that is suitable, away from reserved memory.
>
> Huge thanks to Serget for analysing and proposing a solution to this
> issue.
>
> Fixes: Fixes: 2dcb39645441 ("memblock: do not start bottom-up allocations with kernel_end")
> Debugged-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> Reported-by: Kamal Dasu <kdasu.kdev@gmail.com>
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Thank you!
> ---
> Thomas,
>
> This is intended as a stop-gap solution for 5.12-rc1 and to be picked up
> by the stable team for 5.11. We should find a safer way to avoid these
> problems for 5.13 maybe.
>
> arch/mips/bmips/setup.c | 22 ++++++++++++++++++++++
> arch/mips/include/asm/traps.h | 2 ++
> 2 files changed, 24 insertions(+)
>
> diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
> index 31bcfa4e08b9..0088bd45b892 100644
> --- a/arch/mips/bmips/setup.c
> +++ b/arch/mips/bmips/setup.c
> @@ -149,6 +149,26 @@ void __init plat_time_init(void)
> mips_hpt_frequency = freq;
> }
>
> +static void __init bmips_ebase_reserve(void)
> +{
> + phys_addr_t base, size = VECTORSPACING * 64;
> +
> + switch (current_cpu_type()) {
> + default:
> + case CPU_BMIPS4350:
> + return;
> + case CPU_BMIPS3300:
> + case CPU_BMIPS4380:
> + base = 0x0400;
> + break;
> + case CPU_BMIPS5000:
> + base = 0x1000;
> + break;
> + }
> +
> + memblock_reserve(base, size);
> +}
> +
> void __init plat_mem_setup(void)
> {
> void *dtb;
> @@ -169,6 +189,8 @@ void __init plat_mem_setup(void)
>
> __dt_setup_arch(dtb);
>
> + bmips_ebase_reserve();
> +
> for (q = bmips_quirk_list; q->quirk_fn; q++) {
> if (of_flat_dt_is_compatible(of_get_flat_dt_root(),
> q->compatible)) {
> diff --git a/arch/mips/include/asm/traps.h b/arch/mips/include/asm/traps.h
> index 6aa8f126a43d..0ba6bb7f9618 100644
> --- a/arch/mips/include/asm/traps.h
> +++ b/arch/mips/include/asm/traps.h
> @@ -14,6 +14,8 @@
> #define MIPS_BE_FIXUP 1 /* return to the fixup code */
> #define MIPS_BE_FATAL 2 /* treat as an unrecoverable error */
>
> +#define VECTORSPACING 0x100 /* for EI/VI mode */
> +
> extern void (*board_be_init)(void);
> extern int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
>
> --
> 2.25.1
>
next prev parent reply other threads:[~2021-03-02 22:10 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-17 20:12 [PATCH v2 1/2] mm: cma: allocate cma areas bottom-up Roman Gushchin
2020-12-17 20:12 ` [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end Roman Gushchin
2020-12-19 14:52 ` Wonhyuk Yang
2020-12-19 17:05 ` Roman Gushchin
2020-12-20 6:49 ` Mike Rapoport
2021-01-22 4:37 ` Thiago Jung Bauermann
2021-01-24 2:09 ` Andrew Morton
2021-01-24 7:34 ` Mike Rapoport
2021-01-26 0:30 ` Thiago Jung Bauermann
2021-02-08 23:58 ` Thiago Jung Bauermann
2021-02-28 4:18 ` Florian Fainelli
2021-02-28 9:00 ` Mike Rapoport
2021-02-28 18:19 ` Florian Fainelli
2021-02-28 23:08 ` Serge Semin
2021-03-01 3:50 ` Florian Fainelli
2021-03-01 9:22 ` Serge Semin
2021-03-02 4:09 ` Florian Fainelli
2021-03-02 13:26 ` Serge Semin
2021-03-02 4:19 ` [PATCH] MIPS: BMIPS: Reserve exception base to prevent corruption Florian Fainelli
2021-03-02 8:09 ` Mike Rapoport
2021-03-02 13:54 ` Serge Semin
2021-03-02 19:04 ` Roman Gushchin [this message]
2021-03-02 23:54 ` Thomas Bogendoerfer
2021-03-03 1:30 ` Florian Fainelli
2021-03-03 9:41 ` Thomas Bogendoerfer
2021-03-03 17:45 ` Maciej W. Rozycki
2021-03-03 18:15 ` Thomas Bogendoerfer
2021-03-03 21:50 ` Maciej W. Rozycki
2021-03-01 9:45 ` [PATCH v2 2/2] memblock: do not start bottom-up allocations with kernel_end Mike Rapoport
2021-03-02 3:55 ` Roman Gushchin
2021-03-02 13:08 ` Serge Semin
2021-03-23 18:19 ` [tip: x86/boot] x86/setup: Consolidate early memory reservations tip-bot2 for Mike Rapoport
2020-12-20 6:48 ` [PATCH v2 1/2] mm: cma: allocate cma areas bottom-up Mike Rapoport
2020-12-21 17:05 ` Roman Gushchin
2020-12-23 4:06 ` Andrew Morton
2020-12-23 16:35 ` Roman Gushchin
2020-12-23 22:10 ` Mike Rapoport
2020-12-28 19:36 ` Roman Gushchin
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