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SubjectRe: [RFC 5/8] ARM64: Re-factor flush_ptrace_access


On Friday 02 January 2015 11:49 PM, Oleg Nesterov wrote:
> On 01/02, Oleg Nesterov wrote:
>>
>> On 12/31, Pratyush Anand wrote:
>>>
>>> Re-factor flush_ptrace_access to reuse vma independent part.
>>
>> But for what? The changelog should explain this.
>>
>>> Signed-off-by: Pratyush Anand <panand@redhat.com>
>>> ---
>>> arch/arm64/mm/flush.c | 24 +++++++++++++++---------
>>> 1 file changed, 15 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c
>>> index b6f14e8d2121..9a4dd6f39cfb 100644
>>> --- a/arch/arm64/mm/flush.c
>>> +++ b/arch/arm64/mm/flush.c
>>> @@ -34,19 +34,25 @@ void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
>>> __flush_icache_all();
>>> }
>>>
>>> +static void __flush_ptrace_access(struct page *page, unsigned long uaddr,
>>> + void *kaddr, unsigned long len)
>>> +{
>>> + unsigned long addr = (unsigned long)kaddr;
>>> +
>>> + if (icache_is_aliasing()) {
>>> + __flush_dcache_area(kaddr, len);
>>> + __flush_icache_all();
>>> + } else {
>>> + flush_icache_range(addr, addr + len);
>>> + }
>>> +}
>>> +
>>> static void flush_ptrace_access(struct vm_area_struct *vma, struct page *page,
>>> unsigned long uaddr, void *kaddr,
>>> unsigned long len)
>>> {
>>> - if (vma->vm_flags & VM_EXEC) {
>>> - unsigned long addr = (unsigned long)kaddr;
>>> - if (icache_is_aliasing()) {
>>> - __flush_dcache_area(kaddr, len);
>>> - __flush_icache_all();
>>> - } else {
>>> - flush_icache_range(addr, addr + len);
>>> - }
>>> - }
>>> + if (vma->vm_flags & VM_EXEC)
>>> + __flush_ptrace_access(page, uaddr, kaddr, len);
>>> }
>>
>> So why uprobes can't use flush_ptrace_access() ? flush_uprobe_xol_access() is
>> called by arch_uprobe_copy_ixol(), and xol vma has VM_EXEC bit set.
>
> Ah, sorry, I forgot that arch_uprobe_copy_ixol() doesn't have "vma" so it
> can't use flush_ptrace_access()... perhaps you can update the changelog.
>

OK.. Will improve commit log.

~Pratyush
> Oleg.
>


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