[RFC PATCH 4/5] powerpc: Add VSX regset to compat_regsets

[Pedro Franco de Carvalho <pedromfc@linux.vnet.ibm.com>]

This patch copies the the missing VSX regset to the compat_regsets
array.

Not having this regset can cause issues in fs/binfmt_elf.c in the
fill_thread_core_info function, which iterates over all the regsets
defined in compat_regsets to fill note info for a core dump of a
32-bit thread. However, the number of regset notes allocated for
writing is the number of regsets with core_note_type != 0. If the
regset array has an entry with core_note_type == 0, which is the case
for the missing VSX element, this can cause later regsets to be
written outside the bounds of the allocated notes.

The compat_regset is also missing entries for REGSET_PMR and
REGSET_PKEY, but because these are at the end of the powerpc_regset
enum, the designated initializers for the compat_regset array don't
cause implicit elements to be created, like they did for REGSET_VSX.
---
 arch/powerpc/kernel/ptrace.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 69123feaef9e..2da0668a96dc 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2237,6 +2237,13 @@ static const struct user_regset compat_regsets[] = {
 		.active = vr_active, .get = vr_get, .set = vr_set
 	},
 #endif
+#ifdef CONFIG_VSX
+	[REGSET_VSX] = {
+		.core_note_type = NT_PPC_VSX, .n = 32,
+		.size = sizeof(double), .align = sizeof(double),
+		.active = vsr_active, .get = vsr_get, .set = vsr_set
+	},
+#endif
 #ifdef CONFIG_SPE
 	[REGSET_SPE] = {
 		.core_note_type = NT_PPC_SPE, .n = 35,
-- 
2.13.6