Re: [PATCH] compat: Fix endian issue in union sigval

From: Chris Metcalf
Date: Sat Feb 21 2015 - 02:05:14 EST

On 2/14/2015 6:22 AM, Catalin Marinas wrote:
1. user populates sival_int compat_sigevent and invokes
2. kernel get_compat_sigevent() copies compat_sigevent into the native
sigevent. compat and native sival_int are the same, no problem so
far. The other half of 64-bit sival_ptr is zeroed by a memset in this
function (this other half can be top or bottom, depending on
3. signal is about to be delivered to user via arch code. The
compat_ptr(from->si_ptr) conversion always takes the least
significant part of the native si_ptr. On big endian 64-bit, this is
zero because get_compat_sigevent() populated the top part of si_ptr
with si_int.

Thanks, that makes sense. I was missing the fact that the conversion
issue was actually around the in-kernel 64-bit version of the structure.
Using si_int consistently does seem like it should do the right thing;
I'll post a patch for tilegx32 big-endian to do the right thing here.

Chris Metcalf, EZChip Semiconductor

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