tree 08ec3c3c18fee22ac12d8436ad8f89a5db37226c
parent 05e33fc20ea5e493a2a1e7f1d04f43cdf89f83ed
author H. Peter Anvin <hpa@linux.intel.com> 1314044826 -0700
committer H. Peter Anvin <hpa@linux.intel.com> 1314141610 -0700

x86-32, vdso: On system call restart after SYSENTER, use int $0x80

When we enter a 32-bit system call via SYSENTER or SYSCALL, we shuffle
the arguments to match the int $0x80 calling convention.  This was
probably a design mistake, but it's what it is now.  This causes
errors if the system call as to be restarted.

For SYSENTER, we have to invoke the instruction from the vdso as the
return address is hardcoded.  Accordingly, we can simply replace the
jump in the vdso with an int $0x80 instruction and use the slower
entry point for a post-restart.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/CA%2B55aFztZ=r5wa0x26KJQxvZOaQq8s2v3u50wCyJcA-Sc4g8gQ@mail.gmail.com
Cc: <stable@kernel.org>