FAILED: patch "[PATCH] powerpc/atomic: Use YZ constraints for DS-form instructions" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] powerpc/atomic: Use YZ constraints for DS-form instructions" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-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>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 39190ac7cff1fd15135fa8e658030d9646fdb5f2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024100109-reference-stillness-ee9e@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

39190ac7cff1 ("powerpc/atomic: Use YZ constraints for DS-form instructions")
dc5dac748af9 ("powerpc/64: Add support to build with prefixed instructions")
5017b4594672 ("powerpc/64: Option to build big-endian with ELFv2 ABI")
4b2a9315f20d ("powerpc/64s: POWER10 CPU Kconfig build option")
ff27d9200a98 ("powerpc/405: Fix build failure with GCC 12 (unrecognized opcode: `wrteei')")
446cda1b21d9 ("powerpc/32: Don't always pass -mcpu=powerpc to the compiler")
661aa880398a ("powerpc: Add CONFIG_PPC64_ELF_ABI_V1 and CONFIG_PPC64_ELF_ABI_V2")
dede19be5163 ("powerpc: Remove CONFIG_PPC_HAVE_KUAP and CONFIG_PPC_HAVE_KUEP")
fcf9bb6d32f8 ("powerpc/kuap: Wire-up KUAP on 40x")
25ae981fafaa ("powerpc/nohash: Move setup_kuap out of 8xx.c")
6754862249d3 ("powerpc/kuep: Remove 'nosmep' boot time parameter except for book3s/64")
70428da94c7a ("powerpc/32s: Save content of sr0 to avoid 'mfsr'")
526d4a4c77ae ("powerpc/32s: Do kuep_lock() and kuep_unlock() in assembly")
df415cd75826 ("powerpc/32s: Remove capability to disable KUEP at boottime")
dc3a0e5b83a8 ("powerpc/book3e: Activate KUEP at all time")
ee2631603fdb ("powerpc/44x: Activate KUEP at all time")
13dac4e31e75 ("powerpc/8xx: Activate KUEP at all time")
6c1fa60d368e ("Revert "powerpc: Inline setup_kup()"")
c28573744b74 ("powerpc/64s: Make hash MMU support configurable")
7ebc49031d04 ("powerpc: Rename PPC_NATIVE to PPC_HASH_MMU_NATIVE")

thanks,

greg k-h

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

From 39190ac7cff1fd15135fa8e658030d9646fdb5f2 Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Mon, 16 Sep 2024 22:05:10 +1000
Subject: [PATCH] powerpc/atomic: Use YZ constraints for DS-form instructions

The 'ld' and 'std' instructions require a 4-byte aligned displacement
because they are DS-form instructions. But the "m" asm constraint
doesn't enforce that.

That can lead to build errors if the compiler chooses a non-aligned
displacement, as seen with GCC 14:

  /tmp/ccuSzwiR.s: Assembler messages:
  /tmp/ccuSzwiR.s:2579: Error: operand out of domain (39 is not a multiple of 4)
  make[5]: *** [scripts/Makefile.build:229: net/core/page_pool.o] Error 1

Dumping the generated assembler shows:

  ld 8,39(8)       # MEM[(const struct atomic64_t *)_29].counter, t

Use the YZ constraints to tell the compiler either to generate a DS-form
displacement, or use an X-form instruction, either of which prevents the
build error.

See commit 2d43cc701b96 ("powerpc/uaccess: Fix build errors seen with
GCC 13/14") for more details on the constraint letters.

Fixes: 9f0cbea0d8cc ("[POWERPC] Implement atomic{, 64}_{read, write}() without volatile")
Cc: stable@vger.kernel.org # v2.6.24+
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/all/20240913125302.0a06b4c7@canb.auug.org.au
Tested-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240916120510.2017749-1-mpe@ellerman.id.au

diff --git a/arch/powerpc/include/asm/asm-compat.h b/arch/powerpc/include/asm/asm-compat.h
index b0b209c1df50..f48e644900a2 100644
--- a/arch/powerpc/include/asm/asm-compat.h
+++ b/arch/powerpc/include/asm/asm-compat.h
@@ -37,6 +37,12 @@
 #define STDX_BE	stringify_in_c(stdbrx)
 #endif
 
+#ifdef CONFIG_CC_IS_CLANG
+#define DS_FORM_CONSTRAINT "Z<>"
+#else
+#define DS_FORM_CONSTRAINT "YZ<>"
+#endif
+
 #else /* 32-bit */
 
 /* operations for longs and pointers */
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h
index 5bf6a4d49268..d1ea554c33ed 100644
--- a/arch/powerpc/include/asm/atomic.h
+++ b/arch/powerpc/include/asm/atomic.h
@@ -11,6 +11,7 @@
 #include <asm/cmpxchg.h>
 #include <asm/barrier.h>
 #include <asm/asm-const.h>
+#include <asm/asm-compat.h>
 
 /*
  * Since *_return_relaxed and {cmp}xchg_relaxed are implemented with
@@ -197,7 +198,7 @@ static __inline__ s64 arch_atomic64_read(const atomic64_t *v)
 	if (IS_ENABLED(CONFIG_PPC_KERNEL_PREFIXED))
 		__asm__ __volatile__("ld %0,0(%1)" : "=r"(t) : "b"(&v->counter));
 	else
-		__asm__ __volatile__("ld%U1%X1 %0,%1" : "=r"(t) : "m<>"(v->counter));
+		__asm__ __volatile__("ld%U1%X1 %0,%1" : "=r"(t) : DS_FORM_CONSTRAINT (v->counter));
 
 	return t;
 }
@@ -208,7 +209,7 @@ static __inline__ void arch_atomic64_set(atomic64_t *v, s64 i)
 	if (IS_ENABLED(CONFIG_PPC_KERNEL_PREFIXED))
 		__asm__ __volatile__("std %1,0(%2)" : "=m"(v->counter) : "r"(i), "b"(&v->counter));
 	else
-		__asm__ __volatile__("std%U0%X0 %1,%0" : "=m<>"(v->counter) : "r"(i));
+		__asm__ __volatile__("std%U0%X0 %1,%0" : "=" DS_FORM_CONSTRAINT (v->counter) : "r"(i));
 }
 
 #define ATOMIC64_OP(op, asm_op)						\
diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
index fd594bf6c6a9..4f5a46a77fa2 100644
--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -6,6 +6,7 @@
 #include <asm/page.h>
 #include <asm/extable.h>
 #include <asm/kup.h>
+#include <asm/asm-compat.h>
 
 #ifdef __powerpc64__
 /* We use TASK_SIZE_USER64 as TASK_SIZE is not constant */
@@ -92,12 +93,6 @@ __pu_failed:							\
 		: label)
 #endif
 
-#ifdef CONFIG_CC_IS_CLANG
-#define DS_FORM_CONSTRAINT "Z<>"
-#else
-#define DS_FORM_CONSTRAINT "YZ<>"
-#endif
-
 #ifdef __powerpc64__
 #ifdef CONFIG_PPC_KERNEL_PREFIXED
 #define __put_user_asm2_goto(x, ptr, label)			\