2016-10-17 10:05:27

by Matt Redfearn

[permalink] [raw]
Subject: [PATCH] MIPS: generic: Fix KASLR for generic kernel.

The KASLR code requires that the plat_get_fdt() function return the
address of the device tree, and it must be available early in the boot,
before prom_init() is called. Move the code determining the address of
the device tree into plat_get_fdt, and call that from prom_init().

The fdt pointer will be set up by plat_get_fdt() called from
relocate_kernel initially and once the relocated kernel has started,
prom_init() will use it again to determine the address in the relocated
image.

Fixes: eed0eabd12ef
Signed-off-by: Matt Redfearn <[email protected]>
---

arch/mips/generic/init.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/mips/generic/init.c b/arch/mips/generic/init.c
index 0ea73e845440..d493ccbf274a 100644
--- a/arch/mips/generic/init.c
+++ b/arch/mips/generic/init.c
@@ -30,9 +30,19 @@ static __initdata const void *mach_match_data;

void __init prom_init(void)
{
+ plat_get_fdt();
+ BUG_ON(!fdt);
+}
+
+void __init *plat_get_fdt(void)
+{
const struct mips_machine *check_mach;
const struct of_device_id *match;

+ if (fdt)
+ /* Already set up */
+ return (void *)fdt;
+
if ((fw_arg0 == -2) && !fdt_check_header((void *)fw_arg1)) {
/*
* We booted using the UHI boot protocol, so we have been
@@ -75,12 +85,6 @@ void __init prom_init(void)
/* Retrieve the machine's FDT */
fdt = mach->fdt;
}
-
- BUG_ON(!fdt);
-}
-
-void __init *plat_get_fdt(void)
-{
return (void *)fdt;
}

--
2.7.4


2016-10-17 10:22:42

by James Hogan

[permalink] [raw]
Subject: Re: [PATCH] MIPS: generic: Fix KASLR for generic kernel.

Hi Matt,

On Mon, Oct 17, 2016 at 11:05:09AM +0100, Matt Redfearn wrote:
> The KASLR code requires that the plat_get_fdt() function return the
> address of the device tree, and it must be available early in the boot,
> before prom_init() is called. Move the code determining the address of
> the device tree into plat_get_fdt, and call that from prom_init().
>
> The fdt pointer will be set up by plat_get_fdt() called from
> relocate_kernel initially and once the relocated kernel has started,
> prom_init() will use it again to determine the address in the relocated
> image.
>
> Fixes: eed0eabd12ef

I believe this is the preferred form:

Fixes: eed0eabd12ef ("MIPS: generic: Introduce generic DT-based board support")

Otherwise looks good to me

Reviewed-by: James Hogan <[email protected]>

Cheers
James

> Signed-off-by: Matt Redfearn <[email protected]>
> ---
>
> arch/mips/generic/init.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/arch/mips/generic/init.c b/arch/mips/generic/init.c
> index 0ea73e845440..d493ccbf274a 100644
> --- a/arch/mips/generic/init.c
> +++ b/arch/mips/generic/init.c
> @@ -30,9 +30,19 @@ static __initdata const void *mach_match_data;
>
> void __init prom_init(void)
> {
> + plat_get_fdt();
> + BUG_ON(!fdt);
> +}
> +
> +void __init *plat_get_fdt(void)
> +{
> const struct mips_machine *check_mach;
> const struct of_device_id *match;
>
> + if (fdt)
> + /* Already set up */
> + return (void *)fdt;
> +
> if ((fw_arg0 == -2) && !fdt_check_header((void *)fw_arg1)) {
> /*
> * We booted using the UHI boot protocol, so we have been
> @@ -75,12 +85,6 @@ void __init prom_init(void)
> /* Retrieve the machine's FDT */
> fdt = mach->fdt;
> }
> -
> - BUG_ON(!fdt);
> -}
> -
> -void __init *plat_get_fdt(void)
> -{
> return (void *)fdt;
> }
>
> --
> 2.7.4
>
>


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2016-10-17 15:24:16

by Paul Burton

[permalink] [raw]
Subject: Re: [PATCH] MIPS: generic: Fix KASLR for generic kernel.

On Monday, 17 October 2016 11:05:09 BST Matt Redfearn wrote:
> The KASLR code requires that the plat_get_fdt() function return the
> address of the device tree, and it must be available early in the boot,
> before prom_init() is called. Move the code determining the address of
> the device tree into plat_get_fdt, and call that from prom_init().
>
> The fdt pointer will be set up by plat_get_fdt() called from
> relocate_kernel initially and once the relocated kernel has started,
> prom_init() will use it again to determine the address in the relocated
> image.
>
> Fixes: eed0eabd12ef
> Signed-off-by: Matt Redfearn <[email protected]>
> ---
>
> arch/mips/generic/init.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/arch/mips/generic/init.c b/arch/mips/generic/init.c
> index 0ea73e845440..d493ccbf274a 100644
> --- a/arch/mips/generic/init.c
> +++ b/arch/mips/generic/init.c
> @@ -30,9 +30,19 @@ static __initdata const void *mach_match_data;
>
> void __init prom_init(void)
> {
> + plat_get_fdt();
> + BUG_ON(!fdt);
> +}
> +
> +void __init *plat_get_fdt(void)
> +{
> const struct mips_machine *check_mach;
> const struct of_device_id *match;
>
> + if (fdt)
> + /* Already set up */
> + return (void *)fdt;
> +
> if ((fw_arg0 == -2) && !fdt_check_header((void *)fw_arg1)) {
> /*
> * We booted using the UHI boot protocol, so we have been
> @@ -75,12 +85,6 @@ void __init prom_init(void)
> /* Retrieve the machine's FDT */
> fdt = mach->fdt;
> }
> -
> - BUG_ON(!fdt);
> -}
> -
> -void __init *plat_get_fdt(void)
> -{
> return (void *)fdt;
> }

Hi Matt,

Apart from the Fixes tag niggle James mentioned (which checkpatch ought to
pick up on):

Reviewed-by: Paul Burton <[email protected]>

Thanks,
Paul


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