The patch below does not apply to the 4.4-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.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 32c3fa7cdf0c4a3eb8405fc3e13398de019e828b 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 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

diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h index 9ef0797380cb..f9b0b09153e0 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); \ \ @@ -435,7 +435,7 @@ static inline long atomic64_dec_if_positive(atomic64_t *v) " sub x30, x30, %[ret]\n" " cbnz x30, 1b\n" "2:") - : [ret] "+r" (x0), [v] "+Q" (v->counter) + : [ret] "+&r" (x0), [v] "+Q" (v->counter) : : __LL_SC_CLOBBERS, "cc", "memory");

@@ -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) \