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Helge Deller 71a71fb537 parisc: Fix syscall restarts 
On parisc syscalls which are interrupted by signals sometimes failed to
restart and instead returned -ENOSYS which in the worst case lead to
userspace crashes.
A similiar problem existed on MIPS and was fixed by commit e967ef02
("MIPS: Fix restart of indirect syscalls").

On parisc the current syscall restart code assumes that all syscall
callers load the syscall number in the delay slot of the ble
instruction. That's how it is e.g. done in the unistd.h header file:
	ble 0x100(%sr2, %r0)
	ldi #syscall_nr, %r20
Because of that assumption the current code never restored %r20 before
returning to userspace.

This assumption is at least not true for code which uses the glibc
syscall() function, which instead uses this syntax:
	ble 0x100(%sr2, %r0)
	copy regX, %r20
where regX depend on how the compiler optimizes the code and register
usage.

This patch fixes this problem by adding code to analyze how the syscall
number is loaded in the delay branch and - if needed - copy the syscall
number to regX prior returning to userspace for the syscall restart.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 		2015-12-21 10:16:18 +01:00
..
configs rtmutex: Delete scriptable tester 2015-07-20 11:45:45 +02:00
include parisc: Disable huge pages on Mako machines 2015-12-12 16:45:23 +01:00
kernel parisc: Fix syscall restarts 2015-12-21 10:16:18 +01:00
lib parisc: percpu: update comments referring to __get_cpu_var 2014-12-13 12:42:53 -08:00
math-emu parisc: remove duplicate define 2013-11-07 22:28:15 +01:00
mm Merge branch 'parisc-4.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2015-11-22 12:50:58 -08:00
oprofile oprofile: more whitespace fixes 2008-10-15 20:55:51 +02:00
Kconfig parisc: Add Huge Page and HUGETLBFS support 2015-11-22 12:23:10 +01:00
Kconfig.debug consolidate per-arch stack overflow debugging options 2013-07-04 11:25:39 -07:00
Makefile Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2015-02-19 10:07:08 -08:00
defpalo.conf parisc: switch to gzip-compressed vmlinuz kernel 2013-07-09 22:09:20 +02:00
install.sh parisc: make "make install" not depend on vmlinux 2013-11-07 22:28:06 +01:00
nm
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