Messages in this thread | | | From | Andy Lutomirski <> | Date | Tue, 9 Jun 2015 11:59:06 -0700 | Subject | Re: [PATCH 5/5] x86/asm/entry/32: Simplify ptrace register shuffling |
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On Tue, Jun 9, 2015 at 11:54 AM, Denys Vlasenko <dvlasenk@redhat.com> wrote: > Before this patch, we were clearing pt_regs->r8..r11 on stack. > We can as well just store actual r8..r11 registers there: > they came from userspace, we leak no information by showing them to ptrace. > This allows to get rid of one insn ("xor %eax,%eax"). > Not a big deal, but still... > > After call to syscall_trace_enter(), before this patch we were restoring > clobbered registers and jump to code which converts 32-bit syscall > ABI to 64-bit C ABI. This is unnecessary work, we can combine both > steps into one (similar to what audit code does already).
I think like zeroing it better. There's nothing wrong with zeroing it, and it makes testing (if we ever started testing this stuff) easier, I think.
--Andy
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