[PATCH] add Altivec/VMX state to coredumps

[Mark Nelson <markn@au1.ibm.com>]

Update dump_task_altivec() (that has so far never been put to use)
so that it dumps the Altivec/VMX registers (VR[0] - VR[31], VSCR
and VRSAVE) in the same format as the ptrace get_vrregs() and add
the appropriate glue typedefs and #defines to
include/asm-powerpc/elf.h for it to work.

Signed-off-by: Mark Nelson <markn@au1.ibm.com>
---
 arch/powerpc/kernel/process.c |   28 +++++++++++++++++++++++++---
 include/asm-powerpc/elf.h     |    7 +++++++
 2 files changed, 32 insertions(+), 3 deletions(-)

Index: linux/arch/powerpc/kernel/process.c
===================================================================
--- linux.orig/arch/powerpc/kernel/process.c
+++ linux/arch/powerpc/kernel/process.c
@@ -149,10 +149,32 @@ void flush_altivec_to_thread(struct task
 	}
 }
 
-int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
+int dump_task_altivec(struct task_struct *tsk, elf_vrregset_t *vrregs)
 {
-	flush_altivec_to_thread(current);
-	memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
+	/* ELF_NVRREG includes the VSCR and VRSAVE which we need to save
+	 * separately, see below */
+	const int nregs = ELF_NVRREG - 2;
+	elf_vrreg_t *reg;
+	u32 *dest;
+
+	if (tsk == current)
+		flush_altivec_to_thread(tsk);
+
+	reg = (elf_vrreg_t *)vrregs;
+
+	/* copy the 32 vr registers */
+	memcpy(reg, &tsk->thread.vr[0], nregs * sizeof(*reg));
+	reg += nregs;
+
+	/* copy the vscr */
+	memcpy(reg, &tsk->thread.vscr, sizeof(*reg));
+	reg++;
+
+	/* vrsave is stored in the high 32bit slot of the final 128bits */
+	memset(reg, 0, sizeof(*reg));
+	dest = (u32 *)reg;
+	*dest = tsk->thread.vrsave;
+
 	return 1;
 }
 #endif /* CONFIG_ALTIVEC */
Index: linux/include/asm-powerpc/elf.h
===================================================================
--- linux.orig/include/asm-powerpc/elf.h
+++ linux/include/asm-powerpc/elf.h
@@ -212,6 +212,13 @@ static inline int dump_task_regs(struct 
 extern int dump_task_fpu(struct task_struct *, elf_fpregset_t *); 
 #define ELF_CORE_COPY_FPREGS(tsk, elf_fpregs) dump_task_fpu(tsk, elf_fpregs)
 
+typedef elf_vrregset_t elf_fpxregset_t;
+
+#ifdef CONFIG_ALTIVEC
+extern int dump_task_altivec(struct task_struct *, elf_vrregset_t *vrregs);
+#define ELF_CORE_COPY_XFPREGS(tsk, regs) dump_task_altivec(tsk, regs)
+#endif
+
 #endif /* __KERNEL__ */
 
 /* ELF_HWCAP yields a mask that user programs can use to figure out what