powerpc/ptrace: Enable support for EBB registers

This patch enables support for EBB state registers related
ELF core note NT_PPC_EBB based ptrace requests through
PTRACE_GETREGSET, PTRACE_SETREGSET calls. This is achieved
through adding one new register sets REGSET_EBB in powerpc
corresponding to the ELF core note sections added in this
regard. It also implements the get, set and active functions
for this new register sets added.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

2 files changed, 76 insertions, 0 deletions

diff --git a/arch/powerpc/include/uapi/asm/elf.h b/arch/powerpc/include/uapi/asm/elf.h
index e703c646163b..8c4d71a59259 100644
--- a/arch/powerpc/include/uapi/asm/elf.h
+++ b/arch/powerpc/include/uapi/asm/elf.h
@@ -94,6 +94,7 @@
 #define ELF_NVMX        34      /* includes all vector registers */
 #define ELF_NVSX        32      /* includes all VSX registers */
 #define ELF_NTMSPRREG   3       /* include tfhar, tfiar, texasr */
+#define ELF_NEBB       3       /* includes ebbrr, ebbhr, bescr */
 
 typedef unsigned long elf_greg_t64;
 typedef elf_greg_t64 elf_gregset_t64[ELF_NGREG];
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index a1e166ae4b14..7942f9c575ef 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1760,6 +1760,70 @@ static int tar_set(struct task_struct *target,
                                 &target->thread.tar, 0, sizeof(u64));
         return ret;
 }
+
+static int ebb_active(struct task_struct *target,
+                         const struct user_regset *regset)
+{
+        if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+                return -ENODEV;
+
+        if (target->thread.used_ebb)
+                return regset->n;
+
+        return 0;
+}
+
+static int ebb_get(struct task_struct *target,
+                      const struct user_regset *regset,
+                      unsigned int pos, unsigned int count,
+                      void *kbuf, void __user *ubuf)
+{
+        /* Build tests */
+        BUILD_BUG_ON(TSO(ebbrr) + sizeof(unsigned long) != TSO(ebbhr));
+        BUILD_BUG_ON(TSO(ebbhr) + sizeof(unsigned long) != TSO(bescr));
+
+        if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+                return -ENODEV;
+
+        if (!target->thread.used_ebb)
+                return -ENODATA;
+
+        return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.ebbrr, 0, 3 * sizeof(unsigned long));
+}
+
+static int ebb_set(struct task_struct *target,
+                      const struct user_regset *regset,
+                      unsigned int pos, unsigned int count,
+                      const void *kbuf, const void __user *ubuf)
+{
+        int ret = 0;
+
+        /* Build tests */
+        BUILD_BUG_ON(TSO(ebbrr) + sizeof(unsigned long) != TSO(ebbhr));
+        BUILD_BUG_ON(TSO(ebbhr) + sizeof(unsigned long) != TSO(bescr));
+
+        if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+                return -ENODEV;
+
+        if (target->thread.used_ebb)
+                return -ENODATA;
+
+        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.ebbrr, 0, sizeof(unsigned long));
+
+        if (!ret)
+                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.ebbhr, sizeof(unsigned long),
+                        2 * sizeof(unsigned long));
+
+        if (!ret)
+                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.bescr,
+                        2 * sizeof(unsigned long), 3 * sizeof(unsigned long));
+
+        return ret;
+}
 #endif
 /*
  * These are our native regset flavors.
@@ -1792,6 +1856,7 @@ enum powerpc_regset {
 #endif
 #ifdef CONFIG_PPC_BOOK3S_64
         REGSET_TAR,             /* TAR register */
+        REGSET_EBB,             /* EBB registers */
 #endif
 };
 
@@ -1887,6 +1952,11 @@ static const struct user_regset native_regsets[] = {
                 .size = sizeof(u64), .align = sizeof(u64),
                 .get = tar_get, .set = tar_set
         },
+        [REGSET_EBB] = {
+                .core_note_type = NT_PPC_EBB, .n = ELF_NEBB,
+                .size = sizeof(u64), .align = sizeof(u64),
+                .active = ebb_active, .get = ebb_get, .set = ebb_set
+        },
 #endif
 };
 
@@ -2173,6 +2243,11 @@ static const struct user_regset compat_regsets[] = {
                 .size = sizeof(u64), .align = sizeof(u64),
                 .get = tar_get, .set = tar_set
         },
+        [REGSET_EBB] = {
+                .core_note_type = NT_PPC_EBB, .n = ELF_NEBB,
+                .size = sizeof(u64), .align = sizeof(u64),
+                .active = ebb_active, .get = ebb_get, .set = ebb_set
+        },
 #endif
 };