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SubjectRe: [PATCH v2] powerpc: fix boot on BOOK3S_32 with CONFIG_STRICT_KERNEL_RWX
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Le 22/11/2017 à 00:07, Balbir Singh a écrit :
> On Wed, Nov 22, 2017 at 1:28 AM, Christophe Leroy
> <christophe.leroy@c-s.fr> wrote:
>> On powerpc32, patch_instruction() is called by apply_feature_fixups()
>> which is called from early_init()
>>
>> There is the following note in front of early_init():
>> * Note that the kernel may be running at an address which is different
>> * from the address that it was linked at, so we must use RELOC/PTRRELOC
>> * to access static data (including strings). -- paulus
>>
>> Therefore, slab_is_available() cannot be called yet, and
>> text_poke_area must be addressed with PTRRELOC()
>>
>> Fixes: 37bc3e5fd764f ("powerpc/lib/code-patching: Use alternate map
>> for patch_instruction()")
>> Reported-by: Meelis Roos <mroos@linux.ee>
>> Cc: Balbir Singh <bsingharora@gmail.com>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>> v2: Added missing asm/setup.h
>>
>> arch/powerpc/lib/code-patching.c | 6 ++----
>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
>> index c9de03e0c1f1..d469224c4ada 100644
>> --- a/arch/powerpc/lib/code-patching.c
>> +++ b/arch/powerpc/lib/code-patching.c
>> @@ -21,6 +21,7 @@
>> #include <asm/tlbflush.h>
>> #include <asm/page.h>
>> #include <asm/code-patching.h>
>> +#include <asm/setup.h>
>>
>> static int __patch_instruction(unsigned int *addr, unsigned int instr)
>> {
>> @@ -146,11 +147,8 @@ int patch_instruction(unsigned int *addr, unsigned int instr)
>> * During early early boot patch_instruction is called
>> * when text_poke_area is not ready, but we still need
>> * to allow patching. We just do the plain old patching
>> - * We use slab_is_available and per cpu read * via this_cpu_read
>> - * of text_poke_area. Per-CPU areas might not be up early
>> - * this can create problems with just using this_cpu_read()
>> */
>> - if (!slab_is_available() || !this_cpu_read(text_poke_area))
>> + if (!this_cpu_read(*PTRRELOC(&text_poke_area)))
>> return __patch_instruction(addr, instr);
>
> On ppc64, we call apply_feature_fixups() in early_setup() after we've
> relocated ourselves. Sorry for missing the ppc32 case. I would like to
> avoid PTRRELOC when unnecessary.

What do you suggest then ?

Some #ifdef PPC32 around that ?

Christophe


>
> Balbir Singh.
>

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