[PATCH 1/9] powerpc/lib: Add helper to check if offset is within conditional branch range

[Naveen N. Rao]

Hi Song,
Thanks for the reviews.


Song Liu wrote:
> On Fri, Oct 1, 2021 at 2:16 PM Naveen N. Rao
> <naveen.n.rao at linux.vnet.ibm.com> wrote:
>>
>> Add a helper to check if a given offset is within the branch range for a
>> powerpc conditional branch instruction, and update some sites to use the
>> new helper.
>>
>> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
> 
> Acked-by: Song Liu <songliubraving at fb.com>
> 
> With one nitpick:
> 
>> ---
>>  arch/powerpc/include/asm/code-patching.h | 1 +
>>  arch/powerpc/lib/code-patching.c         | 7 ++++++-
>>  arch/powerpc/net/bpf_jit.h               | 7 +------
>>  3 files changed, 8 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
>> index a95f63788c6b14..4ba834599c4d4c 100644
>> --- a/arch/powerpc/include/asm/code-patching.h
>> +++ b/arch/powerpc/include/asm/code-patching.h
>> @@ -23,6 +23,7 @@
>>  #define BRANCH_ABSOLUTE        0x2
>>
>>  bool is_offset_in_branch_range(long offset);
>> +bool is_offset_in_cond_branch_range(long offset);
>>  int create_branch(struct ppc_inst *instr, const u32 *addr,
>>                   unsigned long target, int flags);
>>  int create_cond_branch(struct ppc_inst *instr, const u32 *addr,
>> diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
>> index f9a3019e37b43c..e2342b9a1ab9c9 100644
>> --- a/arch/powerpc/lib/code-patching.c
>> +++ b/arch/powerpc/lib/code-patching.c
>> @@ -228,6 +228,11 @@ bool is_offset_in_branch_range(long offset)
>>         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
>>  }
>>
>> +bool is_offset_in_cond_branch_range(long offset)
>> +{
>> +       return offset >= -0x8000 && offset <= 0x7FFF && !(offset & 0x3);
>> +}
> 
> Why not inline this one?

Good point. This was modeled after the existing 
is_offset_in_branch_range(), and I guess both of those helpers can be 
inlined. I'll do a separate patch for that.


- Naveen