[PATCH 3.16 107/254] MIPS: Factor out NT_PRFPREG regset access helpers

Ben Hutchings
2018-02-28T16:17:45Z

From: "Maciej W. Rozycki" <macro@mips.com>

commit a03fe72572c12e98f4173f8a535f32468e48b6ec upstream.

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
Patchwork: https://patchwork.linux-mips.org/patch/17925/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/mips/kernel/ptrace.c | 108 +++++++++++++++++++++++++++++++++++-----------
1 file changed, 83 insertions(+), 25 deletions(-)

--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -438,25 +438,36 @@ 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)
@@ -466,27 +477,54 @@ 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 */

- init_fp_ctx(target);
+ 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;
+}

- 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));
+/*
+ * 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)
@@ -497,6 +535,26 @@ 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 */
+
+ init_fp_ctx(target);
+
+ 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,