6.11-stable review patch. If anyone has any objections, please let me know.
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From: Michael Ellerman mpe@ellerman.id.au
commit 39190ac7cff1fd15135fa8e658030d9646fdb5f2 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/include/asm/asm-compat.h | 6 ++++++ arch/powerpc/include/asm/atomic.h | 5 +++-- arch/powerpc/include/asm/uaccess.h | 7 +------ 3 files changed, 10 insertions(+), 8 deletions(-)
--- a/arch/powerpc/include/asm/asm-compat.h +++ b/arch/powerpc/include/asm/asm-compat.h @@ -39,6 +39,12 @@ #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 */ --- 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 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 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) \ --- 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) \