Merge branch 'work.regset' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull ptrace regset updates from Al Viro:
 "Internal regset API changes:

   - regularize copy_regset_{to,from}_user() callers

   - switch to saner calling conventions for ->get()

   - kill user_regset_copyout()

  The ->put() side of things will have to wait for the next cycle,
  unfortunately.

  The balance is about -1KLoC and replacements for ->get() instances are
  a lot saner"

* 'work.regset' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
  regset: kill user_regset_copyout{,_zero}()
  regset(): kill ->get_size()
  regset: kill ->get()
  csky: switch to ->regset_get()
  xtensa: switch to ->regset_get()
  parisc: switch to ->regset_get()
  nds32: switch to ->regset_get()
  nios2: switch to ->regset_get()
  hexagon: switch to ->regset_get()
  h8300: switch to ->regset_get()
  openrisc: switch to ->regset_get()
  riscv: switch to ->regset_get()
  c6x: switch to ->regset_get()
  ia64: switch to ->regset_get()
  arc: switch to ->regset_get()
  arm: switch to ->regset_get()
  sh: convert to ->regset_get()
  arm64: switch to ->regset_get()
  mips: switch to ->regset_get()
  sparc: switch to ->regset_get()
  ...

41 files changed, 1370 insertions, 2349 deletions

diff --git a/arch/arc/kernel/ptrace.c b/arch/arc/kernel/ptrace.c
index f49a054a1016..883391977fdf 100644
--- a/arch/arc/kernel/ptrace.c
+++ b/arch/arc/kernel/ptrace.c
@@ -18,88 +18,61 @@ static struct callee_regs *task_callee_regs(struct task_struct *tsk)
 
 static int genregs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
 	const struct pt_regs *ptregs = task_pt_regs(target);
 	const struct callee_regs *cregs = task_callee_regs(target);
-	int ret = 0;
 	unsigned int stop_pc_val;
 
-#define REG_O_CHUNK(START, END, PTR)	\
-	if (!ret)	\
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
-			offsetof(struct user_regs_struct, START), \
-			offsetof(struct user_regs_struct, END));
-
-#define REG_O_ONE(LOC, PTR)	\
-	if (!ret)		\
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, PTR, \
-			offsetof(struct user_regs_struct, LOC), \
-			offsetof(struct user_regs_struct, LOC) + 4);
-
-#define REG_O_ZERO(LOC)		\
-	if (!ret)		\
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, \
-			offsetof(struct user_regs_struct, LOC), \
-			offsetof(struct user_regs_struct, LOC) + 4);
-
-	REG_O_ZERO(pad);
-	REG_O_ONE(scratch.bta, &ptregs->bta);
-	REG_O_ONE(scratch.lp_start, &ptregs->lp_start);
-	REG_O_ONE(scratch.lp_end, &ptregs->lp_end);
-	REG_O_ONE(scratch.lp_count, &ptregs->lp_count);
-	REG_O_ONE(scratch.status32, &ptregs->status32);
-	REG_O_ONE(scratch.ret, &ptregs->ret);
-	REG_O_ONE(scratch.blink, &ptregs->blink);
-	REG_O_ONE(scratch.fp, &ptregs->fp);
-	REG_O_ONE(scratch.gp, &ptregs->r26);
-	REG_O_ONE(scratch.r12, &ptregs->r12);
-	REG_O_ONE(scratch.r11, &ptregs->r11);
-	REG_O_ONE(scratch.r10, &ptregs->r10);
-	REG_O_ONE(scratch.r9, &ptregs->r9);
-	REG_O_ONE(scratch.r8, &ptregs->r8);
-	REG_O_ONE(scratch.r7, &ptregs->r7);
-	REG_O_ONE(scratch.r6, &ptregs->r6);
-	REG_O_ONE(scratch.r5, &ptregs->r5);
-	REG_O_ONE(scratch.r4, &ptregs->r4);
-	REG_O_ONE(scratch.r3, &ptregs->r3);
-	REG_O_ONE(scratch.r2, &ptregs->r2);
-	REG_O_ONE(scratch.r1, &ptregs->r1);
-	REG_O_ONE(scratch.r0, &ptregs->r0);
-	REG_O_ONE(scratch.sp, &ptregs->sp);
-
-	REG_O_ZERO(pad2);
-
-	REG_O_ONE(callee.r25, &cregs->r25);
-	REG_O_ONE(callee.r24, &cregs->r24);
-	REG_O_ONE(callee.r23, &cregs->r23);
-	REG_O_ONE(callee.r22, &cregs->r22);
-	REG_O_ONE(callee.r21, &cregs->r21);
-	REG_O_ONE(callee.r20, &cregs->r20);
-	REG_O_ONE(callee.r19, &cregs->r19);
-	REG_O_ONE(callee.r18, &cregs->r18);
-	REG_O_ONE(callee.r17, &cregs->r17);
-	REG_O_ONE(callee.r16, &cregs->r16);
-	REG_O_ONE(callee.r15, &cregs->r15);
-	REG_O_ONE(callee.r14, &cregs->r14);
-	REG_O_ONE(callee.r13, &cregs->r13);
-
-	REG_O_ONE(efa, &target->thread.fault_address);
-
-	if (!ret) {
-		if (in_brkpt_trap(ptregs)) {
-			stop_pc_val = target->thread.fault_address;
-			pr_debug("\t\tstop_pc (brk-pt)\n");
-		} else {
-			stop_pc_val = ptregs->ret;
-			pr_debug("\t\tstop_pc (others)\n");
-		}
-
-		REG_O_ONE(stop_pc, &stop_pc_val);
+	membuf_zero(&to, 4);	// pad
+	membuf_store(&to, ptregs->bta);
+	membuf_store(&to, ptregs->lp_start);
+	membuf_store(&to, ptregs->lp_end);
+	membuf_store(&to, ptregs->lp_count);
+	membuf_store(&to, ptregs->status32);
+	membuf_store(&to, ptregs->ret);
+	membuf_store(&to, ptregs->blink);
+	membuf_store(&to, ptregs->fp);
+	membuf_store(&to, ptregs->r26);	// gp
+	membuf_store(&to, ptregs->r12);
+	membuf_store(&to, ptregs->r11);
+	membuf_store(&to, ptregs->r10);
+	membuf_store(&to, ptregs->r9);
+	membuf_store(&to, ptregs->r8);
+	membuf_store(&to, ptregs->r7);
+	membuf_store(&to, ptregs->r6);
+	membuf_store(&to, ptregs->r5);
+	membuf_store(&to, ptregs->r4);
+	membuf_store(&to, ptregs->r3);
+	membuf_store(&to, ptregs->r2);
+	membuf_store(&to, ptregs->r1);
+	membuf_store(&to, ptregs->r0);
+	membuf_store(&to, ptregs->sp);
+	membuf_zero(&to, 4);	// pad2
+	membuf_store(&to, cregs->r25);
+	membuf_store(&to, cregs->r24);
+	membuf_store(&to, cregs->r23);
+	membuf_store(&to, cregs->r22);
+	membuf_store(&to, cregs->r21);
+	membuf_store(&to, cregs->r20);
+	membuf_store(&to, cregs->r19);
+	membuf_store(&to, cregs->r18);
+	membuf_store(&to, cregs->r17);
+	membuf_store(&to, cregs->r16);
+	membuf_store(&to, cregs->r15);
+	membuf_store(&to, cregs->r14);
+	membuf_store(&to, cregs->r13);
+	membuf_store(&to, target->thread.fault_address); // efa
+
+	if (in_brkpt_trap(ptregs)) {
+		stop_pc_val = target->thread.fault_address;
+		pr_debug("\t\tstop_pc (brk-pt)\n");
+	} else {
+		stop_pc_val = ptregs->ret;
+		pr_debug("\t\tstop_pc (others)\n");
 	}
 
-	return ret;
+	return membuf_store(&to, stop_pc_val); // stop_pc
 }
 
 static int genregs_set(struct task_struct *target,
@@ -184,25 +157,20 @@ static int genregs_set(struct task_struct *target,
 #ifdef CONFIG_ISA_ARCV2
 static int arcv2regs_get(struct task_struct *target,
 		       const struct user_regset *regset,
-		       unsigned int pos, unsigned int count,
-		       void *kbuf, void __user *ubuf)
+		       struct membuf to)
 {
 	const struct pt_regs *regs = task_pt_regs(target);
-	int ret, copy_sz;
 
 	if (IS_ENABLED(CONFIG_ARC_HAS_ACCL_REGS))
-		copy_sz = sizeof(struct user_regs_arcv2);
-	else
-		copy_sz = 4;	/* r30 only */
+		/*
+		 * itemized copy not needed like above as layout of regs (r30,r58,r59)
+		 * is exactly same in kernel (pt_regs) and userspace (user_regs_arcv2)
+		 */
+		return membuf_write(&to, &regs->r30, sizeof(struct user_regs_arcv2));
 
-	/*
-	 * itemized copy not needed like above as layout of regs (r30,r58,r59)
-	 * is exactly same in kernel (pt_regs) and userspace (user_regs_arcv2)
-	 */
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &regs->r30,
-				  0, copy_sz);
 
-	return ret;
+	membuf_write(&to, &regs->r30, 4); /* r30 only */
+	return membuf_zero(&to, sizeof(struct user_regs_arcv2) - 4);
 }
 
 static int arcv2regs_set(struct task_struct *target,
@@ -237,7 +205,7 @@ static const struct user_regset arc_regsets[] = {
 	       .n = ELF_NGREG,
 	       .size = sizeof(unsigned long),
 	       .align = sizeof(unsigned long),
-	       .get = genregs_get,
+	       .regset_get = genregs_get,
 	       .set = genregs_set,
 	},
 #ifdef CONFIG_ISA_ARCV2
@@ -246,7 +214,7 @@ static const struct user_regset arc_regsets[] = {
 	       .n = ELF_ARCV2REG,
 	       .size = sizeof(unsigned long),
 	       .align = sizeof(unsigned long),
-	       .get = arcv2regs_get,
+	       .regset_get = arcv2regs_get,
 	       .set = arcv2regs_set,
 	},
 #endif
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index d0f7c8896c96..2771e682220b 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -569,14 +569,9 @@ out:
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	struct pt_regs *regs = task_pt_regs(target);
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   regs,
-				   0, sizeof(*regs));
+	return membuf_write(&to, task_pt_regs(target), sizeof(struct pt_regs));
 }
 
 static int gpr_set(struct task_struct *target,
@@ -602,12 +597,10 @@ static int gpr_set(struct task_struct *target,
 
 static int fpa_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &task_thread_info(target)->fpstate,
-				   0, sizeof(struct user_fp));
+	return membuf_write(&to, &task_thread_info(target)->fpstate,
+				 sizeof(struct user_fp));
 }
 
 static int fpa_set(struct task_struct *target,
@@ -642,41 +635,20 @@ static int fpa_set(struct task_struct *target,
  *	vfp_set() ignores this chunk
  *
  * 1 word for the FPSCR
- *
- * The bounds-checking logic built into user_regset_copyout and friends
- * means that we can make a simple sequence of calls to map the relevant data
- * to/from the specified slice of the user regset structure.
  */
 static int vfp_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	int ret;
 	struct thread_info *thread = task_thread_info(target);
 	struct vfp_hard_struct const *vfp = &thread->vfpstate.hard;
-	const size_t user_fpregs_offset = offsetof(struct user_vfp, fpregs);
 	const size_t user_fpscr_offset = offsetof(struct user_vfp, fpscr);
 
 	vfp_sync_hwstate(thread);
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &vfp->fpregs,
-				  user_fpregs_offset,
-				  user_fpregs_offset + sizeof(vfp->fpregs));
-	if (ret)
-		return ret;
-
-	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-				       user_fpregs_offset + sizeof(vfp->fpregs),
-				       user_fpscr_offset);
-	if (ret)
-		return ret;
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &vfp->fpscr,
-				   user_fpscr_offset,
-				   user_fpscr_offset + sizeof(vfp->fpscr));
+	membuf_write(&to, vfp->fpregs, sizeof(vfp->fpregs));
+	membuf_zero(&to, user_fpscr_offset - sizeof(vfp->fpregs));
+	return membuf_store(&to, vfp->fpscr);
 }
 
 /*
@@ -739,7 +711,7 @@ static const struct user_regset arm_regsets[] = {
 		.n = ELF_NGREG,
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = gpr_get,
+		.regset_get = gpr_get,
 		.set = gpr_set
 	},
 	[REGSET_FPR] = {
@@ -751,7 +723,7 @@ static const struct user_regset arm_regsets[] = {
 		.n = sizeof(struct user_fp) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = fpa_get,
+		.regset_get = fpa_get,
 		.set = fpa_set
 	},
 #ifdef CONFIG_VFP
@@ -764,7 +736,7 @@ static const struct user_regset arm_regsets[] = {
 		.n = ARM_VFPREGS_SIZE / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = vfp_get,
+		.regset_get = vfp_get,
 		.set = vfp_set
 	},
 #endif /* CONFIG_VFP */
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 1e02e98e68dd..d8ebfd813e28 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -474,11 +474,10 @@ static int ptrace_hbp_set_addr(unsigned int note_type,
 
 static int hw_break_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
 	unsigned int note_type = regset->core_note_type;
-	int ret, idx = 0, offset, limit;
+	int ret, idx = 0;
 	u32 info, ctrl;
 	u64 addr;
 
@@ -487,49 +486,21 @@ static int hw_break_get(struct task_struct *target,
 	if (ret)
 		return ret;
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &info, 0,
-				  sizeof(info));
-	if (ret)
-		return ret;
-
-	/* Pad */
-	offset = offsetof(struct user_hwdebug_state, pad);
-	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf, offset,
-				       offset + PTRACE_HBP_PAD_SZ);
-	if (ret)
-		return ret;
-
+	membuf_write(&to, &info, sizeof(info));
+	membuf_zero(&to, sizeof(u32));
 	/* (address, ctrl) registers */
-	offset = offsetof(struct user_hwdebug_state, dbg_regs);
-	limit = regset->n * regset->size;
-	while (count && offset < limit) {
+	while (to.left) {
 		ret = ptrace_hbp_get_addr(note_type, target, idx, &addr);
 		if (ret)
 			return ret;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &addr,
-					  offset, offset + PTRACE_HBP_ADDR_SZ);
-		if (ret)
-			return ret;
-		offset += PTRACE_HBP_ADDR_SZ;
-
 		ret = ptrace_hbp_get_ctrl(note_type, target, idx, &ctrl);
 		if (ret)
 			return ret;
-		ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &ctrl,
-					  offset, offset + PTRACE_HBP_CTRL_SZ);
-		if (ret)
-			return ret;
-		offset += PTRACE_HBP_CTRL_SZ;
-
-		ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					       offset,
-					       offset + PTRACE_HBP_PAD_SZ);
-		if (ret)
-			return ret;
-		offset += PTRACE_HBP_PAD_SZ;
+		membuf_store(&to, addr);
+		membuf_store(&to, ctrl);
+		membuf_zero(&to, sizeof(u32));
 		idx++;
 	}
-
 	return 0;
 }
 
@@ -589,11 +560,10 @@ static int hw_break_set(struct task_struct *target,
 
 static int gpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs;
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
+	return membuf_write(&to, uregs, sizeof(*uregs));
 }
 
 static int gpr_set(struct task_struct *target, const struct user_regset *regset,
@@ -626,8 +596,7 @@ static int fpr_active(struct task_struct *target, const struct user_regset *regs
  */
 static int __fpr_get(struct task_struct *target,
 		     const struct user_regset *regset,
-		     unsigned int pos, unsigned int count,
-		     void *kbuf, void __user *ubuf, unsigned int start_pos)
+		     struct membuf to)
 {
 	struct user_fpsimd_state *uregs;
 
@@ -635,13 +604,11 @@ static int __fpr_get(struct task_struct *target,
 
 	uregs = &target->thread.uw.fpsimd_state;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs,
-				   start_pos, start_pos + sizeof(*uregs));
+	return membuf_write(&to, uregs, sizeof(*uregs));
 }
 
 static int fpr_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	if (!system_supports_fpsimd())
 		return -EINVAL;
@@ -649,7 +616,7 @@ static int fpr_get(struct task_struct *target, const struct user_regset *regset,
 	if (target == current)
 		fpsimd_preserve_current_state();
 
-	return __fpr_get(target, regset, pos, count, kbuf, ubuf, 0);
+	return __fpr_get(target, regset, to);
 }
 
 static int __fpr_set(struct task_struct *target,
@@ -699,15 +666,12 @@ static int fpr_set(struct task_struct *target, const struct user_regset *regset,
 }
 
 static int tls_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	unsigned long *tls = &target->thread.uw.tp_value;
-
 	if (target == current)
 		tls_preserve_current_state();
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, tls, 0, -1);
+	return membuf_store(&to, target->thread.uw.tp_value);
 }
 
 static int tls_set(struct task_struct *target, const struct user_regset *regset,
@@ -727,13 +691,9 @@ static int tls_set(struct task_struct *target, const struct user_regset *regset,
 
 static int system_call_get(struct task_struct *target,
 			   const struct user_regset *regset,
-			   unsigned int pos, unsigned int count,
-			   void *kbuf, void __user *ubuf)
+			   struct membuf to)
 {
-	int syscallno = task_pt_regs(target)->syscallno;
-
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &syscallno, 0, -1);
+	return membuf_store(&to, task_pt_regs(target)->syscallno);
 }
 
 static int system_call_set(struct task_struct *target,
@@ -780,24 +740,10 @@ static unsigned int sve_size_from_header(struct user_sve_header const *header)
 	return ALIGN(header->size, SVE_VQ_BYTES);
 }
 
-static unsigned int sve_get_size(struct task_struct *target,
-				 const struct user_regset *regset)
-{
-	struct user_sve_header header;
-
-	if (!system_supports_sve())
-		return 0;
-
-	sve_init_header_from_task(&header, target);
-	return sve_size_from_header(&header);
-}
-
 static int sve_get(struct task_struct *target,
 		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
-	int ret;
 	struct user_sve_header header;
 	unsigned int vq;
 	unsigned long start, end;
@@ -809,10 +755,7 @@ static int sve_get(struct task_struct *target,
 	sve_init_header_from_task(&header, target);
 	vq = sve_vq_from_vl(header.vl);
 
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, &header,
-				  0, sizeof(header));
-	if (ret)
-		return ret;
+	membuf_write(&to, &header, sizeof(header));
 
 	if (target == current)
 		fpsimd_preserve_current_state();
@@ -821,26 +764,18 @@ static int sve_get(struct task_struct *target,
 
 	BUILD_BUG_ON(SVE_PT_FPSIMD_OFFSET != sizeof(header));
 	if ((header.flags & SVE_PT_REGS_MASK) == SVE_PT_REGS_FPSIMD)
-		return __fpr_get(target, regset, pos, count, kbuf, ubuf,
-				 SVE_PT_FPSIMD_OFFSET);
+		return __fpr_get(target, regset, to);
 
 	/* Otherwise: full SVE case */
 
 	BUILD_BUG_ON(SVE_PT_SVE_OFFSET != sizeof(header));
 	start = SVE_PT_SVE_OFFSET;
 	end = SVE_PT_SVE_FFR_OFFSET(vq) + SVE_PT_SVE_FFR_SIZE(vq);
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  target->thread.sve_state,
-				  start, end);
-	if (ret)
-		return ret;
+	membuf_write(&to, target->thread.sve_state, end - start);
 
 	start = end;
 	end = SVE_PT_SVE_FPSR_OFFSET(vq);
-	ret = user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-				       start, end);
-	if (ret)
-		return ret;
+	membuf_zero(&to, end - start);
 
 	/*
 	 * Copy fpsr, and fpcr which must follow contiguously in
@@ -848,16 +783,11 @@ static int sve_get(struct task_struct *target,
 	 */
 	start = end;
 	end = SVE_PT_SVE_FPCR_OFFSET(vq) + SVE_PT_SVE_FPCR_SIZE;
-	ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				  &target->thread.uw.fpsimd_state.fpsr,
-				  start, end);
-	if (ret)
-		return ret;
+	membuf_write(&to, &target->thread.uw.fpsimd_state.fpsr, end - start);
 
 	start = end;
 	end = sve_size_from_header(&header);
-	return user_regset_copyout_zero(&pos, &count, &kbuf, &ubuf,
-					start, end);
+	return membuf_zero(&to, end - start);
 }
 
 static int sve_set(struct task_struct *target,
@@ -961,8 +891,7 @@ out:
 #ifdef CONFIG_ARM64_PTR_AUTH
 static int pac_mask_get(struct task_struct *target,
 			const struct user_regset *regset,
-			unsigned int pos, unsigned int count,
-			void *kbuf, void __user *ubuf)
+			struct membuf to)
 {
 	/*
 	 * The PAC bits can differ across data and instruction pointers
@@ -978,7 +907,7 @@ static int pac_mask_get(struct task_struct *target,
 	if (!system_supports_address_auth())
 		return -EINVAL;
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &uregs, 0, -1);
+	return membuf_write(&to, &uregs, sizeof(uregs));
 }
 
 #ifdef CONFIG_CHECKPOINT_RESTORE
@@ -1017,8 +946,7 @@ static void pac_address_keys_from_user(struct ptrauth_keys_user *keys,
 
 static int pac_address_keys_get(struct task_struct *target,
 				const struct user_regset *regset,
-				unsigned int pos, unsigned int count,
-				void *kbuf, void __user *ubuf)
+				struct membuf to)
 {
 	struct ptrauth_keys_user *keys = &target->thread.keys_user;
 	struct user_pac_address_keys user_keys;
@@ -1028,8 +956,7 @@ static int pac_address_keys_get(struct task_struct *target,
 
 	pac_address_keys_to_user(&user_keys, keys);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &user_keys, 0, -1);
+	return membuf_write(&to, &user_keys, sizeof(user_keys));
 }
 
 static int pac_address_keys_set(struct task_struct *target,
@@ -1068,8 +995,7 @@ static void pac_generic_keys_from_user(struct ptrauth_keys_user *keys,
 
 static int pac_generic_keys_get(struct task_struct *target,
 				const struct user_regset *regset,
-				unsigned int pos, unsigned int count,
-				void *kbuf, void __user *ubuf)
+				struct membuf to)
 {
 	struct ptrauth_keys_user *keys = &target->thread.keys_user;
 	struct user_pac_generic_keys user_keys;
@@ -1079,8 +1005,7 @@ static int pac_generic_keys_get(struct task_struct *target,
 
 	pac_generic_keys_to_user(&user_keys, keys);
 
-	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-				   &user_keys, 0, -1);
+	return membuf_write(&to, &user_keys, sizeof(user_keys));
 }
 
 static int pac_generic_keys_set(struct task_struct *target,
@@ -1134,7 +1059,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pt_regs) / sizeof(u64),
 		.size = sizeof(u64),
 		.align = sizeof(u64),
-		.get = gpr_get,
+		.regset_get = gpr_get,
 		.set = gpr_set
 	},
 	[REGSET_FPR] = {
@@ -1147,7 +1072,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.size = sizeof(u32),
 		.align = sizeof(u32),
 		.active = fpr_active,
-		.get = fpr_get,
+		.regset_get = fpr_get,
 		.set = fpr_set
 	},
 	[REGSET_TLS] = {
@@ -1155,7 +1080,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = 1,
 		.size = sizeof(void *),
 		.align = sizeof(void *),
-		.get = tls_get,
+		.regset_get = tls_get,
 		.set = tls_set,
 	},
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -1164,7 +1089,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = hw_break_get,
+		.regset_get = hw_break_get,
 		.set = hw_break_set,
 	},
 	[REGSET_HW_WATCH] = {
@@ -1172,7 +1097,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_hwdebug_state) / sizeof(u32),
 		.size = sizeof(u32),
 		.align = sizeof(u32),
-		.get = hw_break_get,
+		.regset_get = hw_break_get,
 		.set = hw_break_set,
 	},
 #endif
@@ -1181,7 +1106,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = 1,
 		.size = sizeof(int),
 		.align = sizeof(int),
-		.get = system_call_get,
+		.regset_get = system_call_get,
 		.set = system_call_set,
 	},
 #ifdef CONFIG_ARM64_SVE
@@ -1191,9 +1116,8 @@ static const struct user_regset aarch64_regsets[] = {
 				  SVE_VQ_BYTES),
 		.size = SVE_VQ_BYTES,
 		.align = SVE_VQ_BYTES,
-		.get = sve_get,
+		.regset_get = sve_get,
 		.set = sve_set,
-		.get_size = sve_get_size,
 	},
 #endif
 #ifdef CONFIG_ARM64_PTR_AUTH
@@ -1202,7 +1126,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pac_mask) / sizeof(u64),
 		.size = sizeof(u64),
 		.align = sizeof(u64),
-		.get = pac_mask_get,
+		.regset_get = pac_mask_get,
 		/* this cannot be set dynamically */
 	},
 #ifdef CONFIG_CHECKPOINT_RESTORE
@@ -1211,7 +1135,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pac_address_keys) / sizeof(__uint128_t),
 		.size = sizeof(__uint128_t),
 		.align = sizeof(__uint128_t),
-		.get = pac_address_keys_get,
+		.regset_get = pac_address_keys_get,
 		.set = pac_address_keys_set,
 	},
 	[REGSET_PACG_KEYS] = {
@@ -1219,7 +1143,7 @@ static const struct user_regset aarch64_regsets[] = {
 		.n = sizeof(struct user_pac_generic_keys) / sizeof(__uint128_t),
 		.size = sizeof(__uint128_t),
 		.align = sizeof(__uint128_t),
-		.get = pac_generic_keys_get,
+		.regset_get = pac_generic_keys_get,
 		.set = pac_generic_keys_set,
 	},
 #endif
@@ -1237,57 +1161,31 @@ enum compat_regset {
 	REGSET_COMPAT_VFP,
 };
 
-static int compat_gpr_get(struct task_struct *target,
-			  const struct user_regset *regset,
-			  unsigned int pos, unsigned int count,
-			  void *kbuf, void __user *ubuf)
+static inline compat_ulong_t compat_get_user_reg(struct task_struct *task, int idx)
 {
-	int ret = 0;
-	unsigned int i, start, num_regs;
+	struct pt_regs *regs = task_pt_regs(task);
 
-	/* Calculate the number of AArch32 registers contained in count */
-	num_regs = count / regset->size;
-
-	/* Convert pos into an register number */
-	start = pos / regset->size;
-
-	if (start + num_regs > regset->n)
-		return -EIO;
-
-	for (i = 0; i < num_regs; ++i) {
-		unsigned int idx = start + i;
-		compat_ulong_t reg;
-
-		switch (idx) {
-		case 15:
-			reg = task_pt_regs(target)->pc;
-			break;
-		case 16:
-			reg = task_pt_regs(target)->pstate;
-			reg = pstate_to_compat_psr(reg);
-			break;
-		case 17:
-			reg = task_pt_regs(target)->orig_x0;