[PATCH] powerpc/64: Implement arch_within_stack_frames

[Christophe Leroy]

Le 14/12/2022 à 12:48, Christophe Leroy a écrit :
> 
> 
> Le 14/12/2022 à 12:39, Nicholas Piggin a écrit :
>> On Wed Dec 14, 2022 at 6:39 PM AEST, Christophe Leroy wrote:
>>>
>>>
>>> Le 14/12/2022 à 05:42, Nicholas Miehlbradt a écrit :
>>>> Walks the stack when copy_{to,from}_user address is in the stack to
>>>> ensure that the object being copied is entirely within a single stack
>>>> frame.
>>>>
>>>> Substatially similar to the x86 implementation except using the back
>>>> chain to traverse the stack and identify stack frame boundaries.
>>>>
>>>> Signed-off-by: Nicholas Miehlbradt <nicholas at linux.ibm.com>
>>>> ---
>>>>    arch/powerpc/Kconfig                   |  1 +
>>>>    arch/powerpc/include/asm/thread_info.h | 38 
>>>> ++++++++++++++++++++++++++
>>>>    2 files changed, 39 insertions(+)
>>>>
>>>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>>>> index 2ca5418457ed..4c59d139ea83 100644
>>>> --- a/arch/powerpc/Kconfig
>>>> +++ b/arch/powerpc/Kconfig
>>>> @@ -198,6 +198,7 @@ config PPC
>>>>        select HAVE_ARCH_KASAN_VMALLOC        if HAVE_ARCH_KASAN
>>>>        select HAVE_ARCH_KFENCE            if 
>>>> ARCH_SUPPORTS_DEBUG_PAGEALLOC
>>>>        select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
>>>> +    select HAVE_ARCH_WITHIN_STACK_FRAMES    if PPC64
>>>
>>> Why don't you do something that works for both PPC32 and PPC64 ?
>>
>> +1
>>
>>>>        select HAVE_ARCH_KGDB
>>>>        select HAVE_ARCH_MMAP_RND_BITS
>>>>        select HAVE_ARCH_MMAP_RND_COMPAT_BITS    if COMPAT
>>>> diff --git a/arch/powerpc/include/asm/thread_info.h 
>>>> b/arch/powerpc/include/asm/thread_info.h
>>>> index af58f1ed3952..efdf39e07884 100644
>>>> --- a/arch/powerpc/include/asm/thread_info.h
>>>> +++ b/arch/powerpc/include/asm/thread_info.h
>>>> @@ -186,6 +186,44 @@ static inline bool 
>>>> test_thread_local_flags(unsigned int flags)
>>>>    #define is_elf2_task() (0)
>>>>    #endif
>>>> +#ifdef CONFIG_PPC64
>>>> +
>>>> +#ifdef CONFIG_PPC64_ELF_ABI_V1
>>>> +#define PARAMETER_SAVE_OFFSET 48
>>>> +#else
>>>> +#define PARAMETER_SAVE_OFFSET 32
>>>> +#endif
>>>
>>> Why not use STACK_INT_FRAME_REGS, defined in asm/ptrace.h ?
>>
>> I think use a STACK_FRAME prefixed define in asm/ptrace.h, but maybe
>> avoid overloading the STACK_INT_ stuff for this.
>>
> 
> Maybe I should have written _already_ defined :
> 
> $ git grep -n STACK_INT_FRAME_REGS arch/powerpc/include/asm/
> arch/powerpc/include/asm/ptrace.h:126:#define STACK_INT_FRAME_REGS 
> (STACK_FRAME_MIN_SIZE + 16)
> arch/powerpc/include/asm/ptrace.h:138:#define STACK_INT_FRAME_REGS 
> STACK_FRAME_MIN_SIZE
> arch/powerpc/include/asm/ptrace.h:155:#define STACK_INT_FRAME_REGS 
> STACK_FRAME_MIN_SIZE
> 

Looks like I misread STACK_FRAME_MIN_SIZE.

So yes, we need a new macro for it.

What about STACK_FRAME_PARAMS ?