arm64/sve: Disentangle <uapi/asm/ptrace.h> from <uapi/asm/sigcontext.h>

Currently, <uapi/asm/sigcontext.h> provides common definitions for
describing SVE context structures that are also used by the ptrace
definitions in <uapi/asm/ptrace.h>.

For this reason, a #include of <asm/sigcontext.h> was added in
ptrace.h, but it this turns out that this can interact badly with
userspace code that tries to include ptrace.h on top of the libc
headers (which may provide their own shadow definitions for
sigcontext.h).

To make the headers easier for userspace to consume, this patch
bounces the common definitions into an __SVE_* namespace and moves
them to a backend header <uapi/asm/sve_context.h> that can be
included by the other headers as appropriate.  This should allow
ptrace.h to be used alongside libc's sigcontext.h (if any) without
ill effects.

This should make the situation unambiguous: <asm/sigcontext.h> is
the header to include for the sigframe-specific definitions, while
<asm/ptrace.h> is the header to include for ptrace-specific
definitions.

To avoid conflicting with existing usage, <asm/sigcontext.h>
remains the canonical way to get the common definitions for
SVE_VQ_MIN, sve_vq_from_vl() etc., both in userspace and in the
kernel: relying on these being defined as a side effect of
including just <asm/ptrace.h> was never intended to be safe.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 18 insertions, 21 deletions

diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 6c40b3db3285..28d77c9ed531 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -23,7 +23,7 @@
 #include <linux/types.h>
 
 #include <asm/hwcap.h>
-#include <asm/sigcontext.h>
+#include <asm/sve_context.h>
 
 
 /*
@@ -130,9 +130,9 @@ struct user_sve_header {
  */
 
 /* Offset from the start of struct user_sve_header to the register data */
-#define SVE_PT_REGS_OFFSET					\
-	((sizeof(struct user_sve_header) + (SVE_VQ_BYTES - 1))	\
-		/ SVE_VQ_BYTES * SVE_VQ_BYTES)
+#define SVE_PT_REGS_OFFSET						\
+	((sizeof(struct user_sve_header) + (__SVE_VQ_BYTES - 1))	\
+		/ __SVE_VQ_BYTES * __SVE_VQ_BYTES)
 
 /*
  * The register data content and layout depends on the value of the
@@ -178,39 +178,36 @@ struct user_sve_header {
  * Additional data might be appended in the future.
  */
 
-#define SVE_PT_SVE_ZREG_SIZE(vq)	SVE_SIG_ZREG_SIZE(vq)
-#define SVE_PT_SVE_PREG_SIZE(vq)	SVE_SIG_PREG_SIZE(vq)
-#define SVE_PT_SVE_FFR_SIZE(vq)		SVE_SIG_FFR_SIZE(vq)
+#define SVE_PT_SVE_ZREG_SIZE(vq)	__SVE_ZREG_SIZE(vq)
+#define SVE_PT_SVE_PREG_SIZE(vq)	__SVE_PREG_SIZE(vq)
+#define SVE_PT_SVE_FFR_SIZE(vq)		__SVE_FFR_SIZE(vq)
 #define SVE_PT_SVE_FPSR_SIZE		sizeof(__u32)
 #define SVE_PT_SVE_FPCR_SIZE		sizeof(__u32)
 
-#define __SVE_SIG_TO_PT(offset) \
-	((offset) - SVE_SIG_REGS_OFFSET + SVE_PT_REGS_OFFSET)
-
 #define SVE_PT_SVE_OFFSET		SVE_PT_REGS_OFFSET
 
 #define SVE_PT_SVE_ZREGS_OFFSET \
-	__SVE_SIG_TO_PT(SVE_SIG_ZREGS_OFFSET)
+	(SVE_PT_REGS_OFFSET + __SVE_ZREGS_OFFSET)
 #define SVE_PT_SVE_ZREG_OFFSET(vq, n) \
-	__SVE_SIG_TO_PT(SVE_SIG_ZREG_OFFSET(vq, n))
+	(SVE_PT_REGS_OFFSET + __SVE_ZREG_OFFSET(vq, n))
 #define SVE_PT_SVE_ZREGS_SIZE(vq) \
-	(SVE_PT_SVE_ZREG_OFFSET(vq, SVE_NUM_ZREGS) - SVE_PT_SVE_ZREGS_OFFSET)
+	(SVE_PT_SVE_ZREG_OFFSET(vq, __SVE_NUM_ZREGS) - SVE_PT_SVE_ZREGS_OFFSET)
 
 #define SVE_PT_SVE_PREGS_OFFSET(vq) \
-	__SVE_SIG_TO_PT(SVE_SIG_PREGS_OFFSET(vq))
+	(SVE_PT_REGS_OFFSET + __SVE_PREGS_OFFSET(vq))
 #define SVE_PT_SVE_PREG_OFFSET(vq, n) \
-	__SVE_SIG_TO_PT(SVE_SIG_PREG_OFFSET(vq, n))
+	(SVE_PT_REGS_OFFSET + __SVE_PREG_OFFSET(vq, n))
 #define SVE_PT_SVE_PREGS_SIZE(vq) \
-	(SVE_PT_SVE_PREG_OFFSET(vq, SVE_NUM_PREGS) - \
+	(SVE_PT_SVE_PREG_OFFSET(vq, __SVE_NUM_PREGS) - \
 		SVE_PT_SVE_PREGS_OFFSET(vq))
 
 #define SVE_PT_SVE_FFR_OFFSET(vq) \
-	__SVE_SIG_TO_PT(SVE_SIG_FFR_OFFSET(vq))
+	(SVE_PT_REGS_OFFSET + __SVE_FFR_OFFSET(vq))
 
 #define SVE_PT_SVE_FPSR_OFFSET(vq)				\
 	((SVE_PT_SVE_FFR_OFFSET(vq) + SVE_PT_SVE_FFR_SIZE(vq) +	\
-			(SVE_VQ_BYTES - 1))			\
-		/ SVE_VQ_BYTES * SVE_VQ_BYTES)
+			(__SVE_VQ_BYTES - 1))			\
+		/ __SVE_VQ_BYTES * __SVE_VQ_BYTES)
 #define SVE_PT_SVE_FPCR_OFFSET(vq) \
 	(SVE_PT_SVE_FPSR_OFFSET(vq) + SVE_PT_SVE_FPSR_SIZE)
 
@@ -221,8 +218,8 @@ struct user_sve_header {
 
 #define SVE_PT_SVE_SIZE(vq, flags)					\
 	((SVE_PT_SVE_FPCR_OFFSET(vq) + SVE_PT_SVE_FPCR_SIZE		\
-			- SVE_PT_SVE_OFFSET + (SVE_VQ_BYTES - 1))	\
-		/ SVE_VQ_BYTES * SVE_VQ_BYTES)
+			- SVE_PT_SVE_OFFSET + (__SVE_VQ_BYTES - 1))	\
+		/ __SVE_VQ_BYTES * __SVE_VQ_BYTES)
 
 #define SVE_PT_SIZE(vq, flags)						\
 	 (((flags) & SVE_PT_REGS_MASK) == SVE_PT_REGS_SVE ?		\