[PATCH 3.18] MIPS: Factor out NT_PRFPREG regset access helpers

[PATCH 3.18] MIPS: Factor out NT_PRFPREG regset access helpers

[Maciej W. Rozycki]

In preparation to fix a commit 72b22bbad1e7 ("MIPS: Don't assume 64-bit
FP registers for FP regset") FCSR access regression factor out
NT_PRFPREG regset access helpers for the non-MSA and the MSA variants
respectively, to avoid having to deal with excessive indentation in the
actual fix.

No functional change, however use `target->thread.fpu.fpr[0]' rather
than `target->thread.fpu.fpr[i]' for FGR holding type size determination
as there's no `i' variable to refer to anymore, and for the factored out
`i' variable declaration use `unsigned int' rather than `unsigned' as
its type, following the common style.

Signed-off-by: Maciej W. Rozycki <macro@mips.com>
Fixes: 72b22bbad1e7 ("MIPS: Don't assume 64-bit FP registers for FP regset")
Cc: James Hogan <james.hogan@mips.com>
Cc: Paul Burton <Paul.Burton@mips.com>
Cc: Alex Smith <alex@alex-smith.me.uk>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # v3.15+
Patchwork: https://patchwork.linux-mips.org/patch/17925/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---
Hi,

 This is a (mechanically regenerated) version of commit a03fe72572c1 for
3.18-stable and before.  No functional changes.  Please apply.

  Maciej

---
 arch/mips/kernel/ptrace.c |  106 +++++++++++++++++++++++++++++++++++-----------
 1 file changed, 82 insertions(+), 24 deletions(-)

linux-mips-nt-prfpreg-factor-out.diff
Index: linux-stable-el/arch/mips/kernel/ptrace.c
===================================================================
--- linux-stable-el.orig/arch/mips/kernel/ptrace.c	2018-01-10 18:16:16.000000000 +0000
+++ linux-stable-el/arch/mips/kernel/ptrace.c	2018-01-10 20:00:49.092601000 +0000
@@ -400,25 +400,36 @@ static int gpr64_set(struct task_struct 
 
 #endif /* CONFIG_64BIT */
 
-static int fpr_get(struct task_struct *target,
-		   const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+/*
+ * Copy the floating-point context to the supplied NT_PRFPREG buffer,
+ * !CONFIG_CPU_HAS_MSA variant.  FP context's general register slots
+ * correspond 1:1 to buffer slots.
+ */
+static int fpr_get_fpa(struct task_struct *target,
+		       unsigned int *pos, unsigned int *count,
+		       void **kbuf, void __user **ubuf)
 {
-	unsigned i;
-	int err;
-	u64 fpr_val;
-
-	/* XXX fcr31  */
+	return user_regset_copyout(pos, count, kbuf, ubuf,
+				   &target->thread.fpu,
+				   0, sizeof(elf_fpregset_t));
+}
 
-	if (sizeof(target->thread.fpu.fpr[i]) == sizeof(elf_fpreg_t))
-		return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
-					   &target->thread.fpu,
-					   0, sizeof(elf_fpregset_t));
+/*
+ * Copy the floating-point context to the supplied NT_PRFPREG buffer,
+ * CONFIG_CPU_HAS_MSA variant.  Only lower 64 bits of FP context's
+ * general register slots are copied to buffer slots.
+ */
+static int fpr_get_msa(struct task_struct *target,
+		       unsigned int *pos, unsigned int *count,
+		       void **kbuf, void __user **ubuf)
+{
+	unsigned int i;
+	u64 fpr_val;
+	int err;
 
 	for (i = 0; i < NUM_FPU_REGS; i++) {
 		fpr_val = get_fpr64(&target->thread.fpu.fpr[i], 0);
-		err = user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+		err = user_regset_copyout(pos, count, kbuf, ubuf,
 					  &fpr_val, i * sizeof(elf_fpreg_t),
 					  (i + 1) * sizeof(elf_fpreg_t));
 		if (err)
@@ -428,25 +439,54 @@ static int fpr_get(struct task_struct *t
 	return 0;
 }
 
-static int fpr_set(struct task_struct *target,
+/* Copy the floating-point context to the supplied NT_PRFPREG buffer.  */
+static int fpr_get(struct task_struct *target,
 		   const struct user_regset *regset,
 		   unsigned int pos, unsigned int count,
-		   const void *kbuf, const void __user *ubuf)
+		   void *kbuf, void __user *ubuf)
 {
-	unsigned i;
 	int err;
-	u64 fpr_val;
 
 	/* XXX fcr31  */
 
-	if (sizeof(target->thread.fpu.fpr[i]) == sizeof(elf_fpreg_t))
-		return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
-					  &target->thread.fpu,
-					  0, sizeof(elf_fpregset_t));
+	if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
+		err = fpr_get_fpa(target, &pos, &count, &kbuf, &ubuf);
+	else
+		err = fpr_get_msa(target, &pos, &count, &kbuf, &ubuf);
+
+	return err;
+}
+
+/*
+ * Copy the supplied NT_PRFPREG buffer to the floating-point context,
+ * !CONFIG_CPU_HAS_MSA variant.   Buffer slots correspond 1:1 to FP
+ * context's general register slots.
+ */
+static int fpr_set_fpa(struct task_struct *target,
+		       unsigned int *pos, unsigned int *count,
+		       const void **kbuf, const void __user **ubuf)
+{
+	return user_regset_copyin(pos, count, kbuf, ubuf,
+				  &target->thread.fpu,
+				  0, sizeof(elf_fpregset_t));
+}
+
+/*
+ * Copy the supplied NT_PRFPREG buffer to the floating-point context,
+ * CONFIG_CPU_HAS_MSA variant.  Buffer slots are copied to lower 64
+ * bits only of FP context's general register slots.
+ */
+static int fpr_set_msa(struct task_struct *target,
+		       unsigned int *pos, unsigned int *count,
+		       const void **kbuf, const void __user **ubuf)
+{
+	unsigned int i;
+	u64 fpr_val;
+	int err;
 
 	BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
-	for (i = 0; i < NUM_FPU_REGS && count >= sizeof(elf_fpreg_t); i++) {
-		err = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+	for (i = 0; i < NUM_FPU_REGS && *count >= sizeof(elf_fpreg_t); i++) {
+		err = user_regset_copyin(pos, count, kbuf, ubuf,
 					 &fpr_val, i * sizeof(elf_fpreg_t),
 					 (i + 1) * sizeof(elf_fpreg_t));
 		if (err)
@@ -457,6 +497,24 @@ static int fpr_set(struct task_struct *t
 	return 0;
 }
 
+/* Copy the supplied NT_PRFPREG buffer to the floating-point context.  */
+static int fpr_set(struct task_struct *target,
+		   const struct user_regset *regset,
+		   unsigned int pos, unsigned int count,
+		   const void *kbuf, const void __user *ubuf)
+{
+	int err;
+
+	/* XXX fcr31  */
+
+	if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
+		err = fpr_set_fpa(target, &pos, &count, &kbuf, &ubuf);
+	else
+		err = fpr_set_msa(target, &pos, &count, &kbuf, &ubuf);
+
+	return err;
+}
+
 enum mips_regset {
 	REGSET_GPR,
 	REGSET_FPR,

Re: [PATCH 3.18] MIPS: Factor out NT_PRFPREG regset access helpers

[Greg KH]

On Thu, Jan 11, 2018 at 12:25:31AM +0000, Maciej W. Rozycki wrote:
> In preparation to fix a commit 72b22bbad1e7 ("MIPS: Don't assume 64-bit
> FP registers for FP regset") FCSR access regression factor out
> NT_PRFPREG regset access helpers for the non-MSA and the MSA variants
> respectively, to avoid having to deal with excessive indentation in the
> actual fix.
> 
> No functional change, however use `target->thread.fpu.fpr[0]' rather
> than `target->thread.fpu.fpr[i]' for FGR holding type size determination
> as there's no `i' variable to refer to anymore, and for the factored out
> `i' variable declaration use `unsigned int' rather than `unsigned' as
> its type, following the common style.
> 
> Signed-off-by: Maciej W. Rozycki <macro@mips.com>
> Fixes: 72b22bbad1e7 ("MIPS: Don't assume 64-bit FP registers for FP regset")
> Cc: James Hogan <james.hogan@mips.com>
> Cc: Paul Burton <Paul.Burton@mips.com>
> Cc: Alex Smith <alex@alex-smith.me.uk>
> Cc: Dave Martin <Dave.Martin@arm.com>
> Cc: linux-mips@linux-mips.org
> Cc: linux-kernel@vger.kernel.org
> Cc: stable@vger.kernel.org # v3.15+
> Patchwork: https://patchwork.linux-mips.org/patch/17925/
> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
> ---
> Hi,
> 
>  This is a (mechanically regenerated) version of commit a03fe72572c1 for
> 3.18-stable and before.  No functional changes.  Please apply.

Can you send all of these as a patch series, as I have no idea what
order to apply these in and my first guess was all wrong, and nothing
applied at all :(

thanks,

greg k-h

Re: [PATCH 3.18] MIPS: Factor out NT_PRFPREG regset access helpers

[Maciej W. Rozycki]

On Thu, 11 Jan 2018, Greg KH wrote:

> Can you send all of these as a patch series, as I have no idea what
> order to apply these in and my first guess was all wrong, and nothing
> applied at all :(

 OK, will do, with a dummy introduction.  Apologies for the complication.

  Maciej