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Commit d1b6ba82 authored by Max Filippov's avatar Max Filippov
Browse files

xtensa: fix a6 and a7 handling in fast_syscall_xtensa 



Remove restoring a6 on some return paths and instead modify and restore
it in a single place, using symbolic name.
Correctly restore a7 from PT_AREG7 in case of illegal a6 value.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
parent a83b02e9

arch/xtensa/kernel/entry.S

+5 −7
Original line number Diff line number Diff line
@@ -1001,9 +1001,8 @@ ENTRY(fast_syscall_xtensa) 
	movi	a7, 4			# sizeof(unsigned int)

	access_ok a3, a7, a0, a2, .Leac	# a0: scratch reg, a2: sp



	addi	a6, a6, -1		# assuming SYS_XTENSA_ATOMIC_SET = 1

	_bgeui	a6, SYS_XTENSA_COUNT - 1, .Lill

	_bnei	a6, SYS_XTENSA_ATOMIC_CMP_SWP - 1, .Lnswp

	_bgeui	a6, SYS_XTENSA_COUNT, .Lill

	_bnei	a6, SYS_XTENSA_ATOMIC_CMP_SWP, .Lnswp



	/* Fall through for ATOMIC_CMP_SWP. */
@@ -1015,27 +1014,26 @@ TRY s32i a5, a3, 0 # different, modify value 
	l32i	a7, a2, PT_AREG7	# restore a7

	l32i	a0, a2, PT_AREG0	# restore a0

	movi	a2, 1			# and return 1

	addi	a6, a6, 1		# restore a6 (really necessary?)

	rfe



1:	l32i	a7, a2, PT_AREG7	# restore a7

	l32i	a0, a2, PT_AREG0	# restore a0

	movi	a2, 0			# return 0 (note that we cannot set

	addi	a6, a6, 1		# restore a6 (really necessary?)

	rfe



.Lnswp:	/* Atomic set, add, and exg_add. */



TRY	l32i	a7, a3, 0		# orig

	addi	a6, a6, -SYS_XTENSA_ATOMIC_SET

	add	a0, a4, a7		# + arg

	moveqz	a0, a4, a6		# set

	addi	a6, a6, SYS_XTENSA_ATOMIC_SET

TRY	s32i	a0, a3, 0		# write new value



	mov	a0, a2

	mov	a2, a7

	l32i	a7, a0, PT_AREG7	# restore a7

	l32i	a0, a0, PT_AREG0	# restore a0

	addi	a6, a6, 1		# restore a6 (really necessary?)

	rfe



CATCH
@@ -1044,7 +1042,7 @@ CATCH 
	movi	a2, -EFAULT

	rfe



.Lill:	l32i	a7, a2, PT_AREG0	# restore a7

.Lill:	l32i	a7, a2, PT_AREG7	# restore a7

	l32i	a0, a2, PT_AREG0	# restore a0

	movi	a2, -EINVAL

	rfe