Re: FAILED: patch "[PATCH] arm64: lse: Add early clobbers to some input/output asm" failed to apply to 4.9-stable tree

[Will Deacon <will.deacon@arm.com>]

On Sat, May 26, 2018 at 03:11:32PM +0200, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.9-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Here's a backport of 32c3fa7cdf0c ("arm64: lse: Add early clobbers to some
input/output asm operands") for 4.9-stable.

Will

--->8

>From 551176f19a3ef5c170ced0e395e6c0c5e80d90eb Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Mon, 21 May 2018 17:44:57 +0100
Subject: [PATCH] arm64: lse: Add early clobbers to some input/output asm
 operands

For LSE atomics that read and write a register operand, we need to
ensure that these operands are annotated as "early clobber" if the
register is written before all of the input operands have been consumed.
Failure to do so can result in the compiler allocating the same register
to both operands, leading to splats such as:

 Unable to handle kernel paging request at virtual address 11111122222221
 [...]
 x1 : 1111111122222222 x0 : 1111111122222221
 Process swapper/0 (pid: 1, stack limit = 0x000000008209f908)
 Call trace:
  test_atomic64+0x1360/0x155c

where x0 has been allocated as both the value to be stored and also the
atomic_t pointer.

This patch adds the missing clobbers.

Cc: <stable@vger.kernel.org> # 4.9 backport
Cc: Dave Martin <dave.martin@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Reported-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/include/asm/atomic_lse.h | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h
index 7457ce082b5f..d32a0160c89f 100644
--- a/arch/arm64/include/asm/atomic_lse.h
+++ b/arch/arm64/include/asm/atomic_lse.h
@@ -117,7 +117,7 @@ static inline void atomic_and(int i, atomic_t *v)
 	/* LSE atomics */
 	"	mvn	%w[i], %w[i]\n"
 	"	stclr	%w[i], %[v]")
-	: [i] "+r" (w0), [v] "+Q" (v->counter)
+	: [i] "+&r" (w0), [v] "+Q" (v->counter)
 	: "r" (x1)
 	: __LL_SC_CLOBBERS);
 }
@@ -135,7 +135,7 @@ static inline int atomic_fetch_and##name(int i, atomic_t *v)		\
 	/* LSE atomics */						\
 	"	mvn	%w[i], %w[i]\n"					\
 	"	ldclr" #mb "	%w[i], %w[i], %[v]")			\
-	: [i] "+r" (w0), [v] "+Q" (v->counter)				\
+	: [i] "+&r" (w0), [v] "+Q" (v->counter)				\
 	: "r" (x1)							\
 	: __LL_SC_CLOBBERS, ##cl);					\
 									\
@@ -161,7 +161,7 @@ static inline void atomic_sub(int i, atomic_t *v)
 	/* LSE atomics */
 	"	neg	%w[i], %w[i]\n"
 	"	stadd	%w[i], %[v]")
-	: [i] "+r" (w0), [v] "+Q" (v->counter)
+	: [i] "+&r" (w0), [v] "+Q" (v->counter)
 	: "r" (x1)
 	: __LL_SC_CLOBBERS);
 }
@@ -180,7 +180,7 @@ static inline int atomic_sub_return##name(int i, atomic_t *v)		\
 	"	neg	%w[i], %w[i]\n"					\
 	"	ldadd" #mb "	%w[i], w30, %[v]\n"			\
 	"	add	%w[i], %w[i], w30")				\
-	: [i] "+r" (w0), [v] "+Q" (v->counter)				\
+	: [i] "+&r" (w0), [v] "+Q" (v->counter)				\
 	: "r" (x1)							\
 	: __LL_SC_CLOBBERS , ##cl);					\
 									\
@@ -207,7 +207,7 @@ static inline int atomic_fetch_sub##name(int i, atomic_t *v)		\
 	/* LSE atomics */						\
 	"	neg	%w[i], %w[i]\n"					\
 	"	ldadd" #mb "	%w[i], %w[i], %[v]")			\
-	: [i] "+r" (w0), [v] "+Q" (v->counter)				\
+	: [i] "+&r" (w0), [v] "+Q" (v->counter)				\
 	: "r" (x1)							\
 	: __LL_SC_CLOBBERS, ##cl);					\
 									\
@@ -314,7 +314,7 @@ static inline void atomic64_and(long i, atomic64_t *v)
 	/* LSE atomics */
 	"	mvn	%[i], %[i]\n"
 	"	stclr	%[i], %[v]")
-	: [i] "+r" (x0), [v] "+Q" (v->counter)
+	: [i] "+&r" (x0), [v] "+Q" (v->counter)
 	: "r" (x1)
 	: __LL_SC_CLOBBERS);
 }
@@ -332,7 +332,7 @@ static inline long atomic64_fetch_and##name(long i, atomic64_t *v)	\
 	/* LSE atomics */						\
 	"	mvn	%[i], %[i]\n"					\
 	"	ldclr" #mb "	%[i], %[i], %[v]")			\
-	: [i] "+r" (x0), [v] "+Q" (v->counter)				\
+	: [i] "+&r" (x0), [v] "+Q" (v->counter)				\
 	: "r" (x1)							\
 	: __LL_SC_CLOBBERS, ##cl);					\
 									\
@@ -358,7 +358,7 @@ static inline void atomic64_sub(long i, atomic64_t *v)
 	/* LSE atomics */
 	"	neg	%[i], %[i]\n"
 	"	stadd	%[i], %[v]")
-	: [i] "+r" (x0), [v] "+Q" (v->counter)
+	: [i] "+&r" (x0), [v] "+Q" (v->counter)
 	: "r" (x1)
 	: __LL_SC_CLOBBERS);
 }
@@ -377,7 +377,7 @@ static inline long atomic64_sub_return##name(long i, atomic64_t *v)	\
 	"	neg	%[i], %[i]\n"					\
 	"	ldadd" #mb "	%[i], x30, %[v]\n"			\
 	"	add	%[i], %[i], x30")				\
-	: [i] "+r" (x0), [v] "+Q" (v->counter)				\
+	: [i] "+&r" (x0), [v] "+Q" (v->counter)				\
 	: "r" (x1)							\
 	: __LL_SC_CLOBBERS, ##cl);					\
 									\
@@ -404,7 +404,7 @@ static inline long atomic64_fetch_sub##name(long i, atomic64_t *v)	\
 	/* LSE atomics */						\
 	"	neg	%[i], %[i]\n"					\
 	"	ldadd" #mb "	%[i], %[i], %[v]")			\
-	: [i] "+r" (x0), [v] "+Q" (v->counter)				\
+	: [i] "+&r" (x0), [v] "+Q" (v->counter)				\
 	: "r" (x1)							\
 	: __LL_SC_CLOBBERS, ##cl);					\
 									\
@@ -516,7 +516,7 @@ static inline long __cmpxchg_double##name(unsigned long old1,		\
 	"	eor	%[old1], %[old1], %[oldval1]\n"			\
 	"	eor	%[old2], %[old2], %[oldval2]\n"			\
 	"	orr	%[old1], %[old1], %[old2]")			\
-	: [old1] "+r" (x0), [old2] "+r" (x1),				\
+	: [old1] "+&r" (x0), [old2] "+&r" (x1),				\
 	  [v] "+Q" (*(unsigned long *)ptr)				\
 	: [new1] "r" (x2), [new2] "r" (x3), [ptr] "r" (x4),		\
 	  [oldval1] "r" (oldval1), [oldval2] "r" (oldval2)		\
-- 
2.1.4