From: Mark Rutland <mark.rutland@arm.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Giancarlo Ferrari <giancarlo.ferrari89@gmail.com>,
linux-kernel@vger.kernel.org, penberg@kernel.org,
geert@linux-m68k.org, linux-arm-kernel@lists.infradead.org,
akpm@linux-foundation.org, rppt@kernel.org,
giancarlo.ferrari@nokia.com
Subject: Re: [PATCH] ARM: kexec: Fix panic after TLB are invalidated
Date: Mon, 1 Feb 2021 13:57:14 +0000 [thread overview]
Message-ID: <20210201135714.GB66060@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20210201130344.GF1463@shell.armlinux.org.uk>
On Mon, Feb 01, 2021 at 01:03:45PM +0000, Russell King - ARM Linux admin wrote:
> On Mon, Feb 01, 2021 at 12:47:20PM +0000, Mark Rutland wrote:
> > 1. copy reloc code into buffer
> > 2. alter variables in copy of reloc code
> > 3. branch to buffer
> >
> > ... which would avoid this class of problem too.
>
> Yep, slightly messy to do though:
>
> diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
> index 5d84ad333f05..6058e0d3a40d 100644
> --- a/arch/arm/kernel/machine_kexec.c
> +++ b/arch/arm/kernel/machine_kexec.c
> @@ -174,18 +174,27 @@ void machine_kexec(struct kimage *image)
>
> reboot_code_buffer = page_address(image->control_code_page);
>
> - /* Prepare parameters for reboot_code_buffer*/
> - set_kernel_text_rw();
> - kexec_start_address = image->start;
> - kexec_indirection_page = page_list;
> - kexec_mach_type = machine_arch_type;
> - kexec_boot_atags = image->arch.kernel_r2;
> -
> /* copy our kernel relocation code to the control code page */
> reboot_entry = fncpy(reboot_code_buffer,
> &relocate_new_kernel,
> relocate_new_kernel_size);
>
> +#define set(what, val) \
> + do { \
> + uintptr_t __funcp_address; \
> + int __offset; \
> + void *__ptr; \
> + asm("" : "=r" (__funcp_address) : "0" (&relocate_new_kernel)); \
> + __offset = (uintptr_t)&(what) - (__funcp_address & ~1); \
> + __ptr = reboot_code_buffer + __offset; \
> + *(__typeof__(&(what)))__ptr = val; \
> + } while (0)
> +
> + set(kexec_start_address, image->start);
> + set(kexec_indirection_page, page_list);
> + set(kexec_mach_type, machine_arch_type);
> + set(kexec_boot_atags, image->arch.kernel_r2);
We could simplify this slightly if we moved the kexec_& variables into a
struct (using asm-offset KEXEC_VAR_* offsets and a KEXEC_VAR_SIZE region
reserved in the asm), then here we could do something like:
static struct kexec_vars *kexec_buffer_vars(void *buffer)
{
unsigned long code = ((unisigned long)relocate_new_kernel) & ~1;
unsigned long vars - (unsigned long)relocate_vars;
unsigned long offset = vars - code;
return buffer + offset;
}
... and in machine_kexec() do:
struct kexec_vars *kv = kexec_buffer_vars(reboot_code_buffer);
kv->start_address = image->start;
kv->indirection_page = page_list;
kv->mach_type = machine-arch_type;
kv->boot_atags = arch.kernel_r2;
... if that looks any better to you?
Mark.
next prev parent reply other threads:[~2021-02-01 13:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-01 0:44 [PATCH] ARM: kexec: Fix panic after TLB are invalidated Giancarlo Ferrari
2021-02-01 11:34 ` Russell King - ARM Linux admin
2021-02-01 12:47 ` Mark Rutland
2021-02-01 13:03 ` Russell King - ARM Linux admin
2021-02-01 13:57 ` Mark Rutland [this message]
2021-02-01 16:08 ` Russell King - ARM Linux admin
2021-02-01 16:32 ` Mark Rutland
2021-02-01 16:37 ` Russell King - ARM Linux admin
2021-02-01 20:07 ` Giancarlo Ferrari
2021-02-01 20:16 ` Russell King - ARM Linux admin
2021-02-01 22:18 ` Giancarlo Ferrari
2021-02-04 23:48 ` Giancarlo Ferrari
2021-02-05 0:18 ` Russell King - ARM Linux admin
2021-02-05 0:40 ` Giancarlo Ferrari
2021-02-05 0:45 ` Giancarlo Ferrari
2021-02-05 9:44 ` Russell King - ARM Linux admin
2021-02-05 14:36 ` Giancarlo Ferrari
2021-02-01 14:39 ` Giancarlo Ferrari
2021-02-01 15:30 ` Mark Rutland
2021-02-01 19:09 ` Giancarlo Ferrari
-- strict thread matches above, loose matches on Subject: below --
2021-01-12 16:49 Giancarlo Ferrari
2021-02-01 10:10 ` Giancarlo Ferrari
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