powerpc/ptrace: Enable support for Performance Monitor registers

This patch enables support for Performance monitor registers related
ELF core note NT_PPC_PMU based ptrace requests through
PTRACE_GETREGSET, PTRACE_SETREGSET calls. This is achieved
through adding one new register sets REGSET_PMU 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, 77 insertions, 1 deletions

diff --git a/arch/powerpc/include/uapi/asm/elf.h b/arch/powerpc/include/uapi/asm/elf.h
index 8c4d71a59259..3a9e44c45c78 100644
--- a/arch/powerpc/include/uapi/asm/elf.h
+++ b/arch/powerpc/include/uapi/asm/elf.h
@@ -94,7 +94,8 @@
 #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 */
+#define ELF_NEBB        3       /* includes ebbrr, ebbhr, bescr */
+#define ELF_NPMU        5       /* includes siar, sdar, sier, mmcr2, mmcr0 */
 
 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 7942f9c575ef..4f3c5756cc09 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1824,6 +1824,75 @@ static int ebb_set(struct task_struct *target,
 
         return ret;
 }
+static int pmu_active(struct task_struct *target,
+                         const struct user_regset *regset)
+{
+        if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+                return -ENODEV;
+
+        return regset->n;
+}
+
+static int pmu_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(siar) + sizeof(unsigned long) != TSO(sdar));
+        BUILD_BUG_ON(TSO(sdar) + sizeof(unsigned long) != TSO(sier));
+        BUILD_BUG_ON(TSO(sier) + sizeof(unsigned long) != TSO(mmcr2));
+        BUILD_BUG_ON(TSO(mmcr2) + sizeof(unsigned long) != TSO(mmcr0));
+
+        if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+                return -ENODEV;
+
+        return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.siar, 0,
+                        5 * sizeof(unsigned long));
+}
+
+static int pmu_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(siar) + sizeof(unsigned long) != TSO(sdar));
+        BUILD_BUG_ON(TSO(sdar) + sizeof(unsigned long) != TSO(sier));
+        BUILD_BUG_ON(TSO(sier) + sizeof(unsigned long) != TSO(mmcr2));
+        BUILD_BUG_ON(TSO(mmcr2) + sizeof(unsigned long) != TSO(mmcr0));
+
+        if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+                return -ENODEV;
+
+        ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.siar, 0,
+                        sizeof(unsigned long));
+
+        if (!ret)
+                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.sdar, sizeof(unsigned long),
+                        2 * sizeof(unsigned long));
+
+        if (!ret)
+                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.sier, 2 * sizeof(unsigned long),
+                        3 * sizeof(unsigned long));
+
+        if (!ret)
+                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.mmcr2, 3 * sizeof(unsigned long),
+                        4 * sizeof(unsigned long));
+
+        if (!ret)
+                ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+                        &target->thread.mmcr0, 4 * sizeof(unsigned long),
+                        5 * sizeof(unsigned long));
+        return ret;
+}
 #endif
 /*
  * These are our native regset flavors.
@@ -1857,6 +1926,7 @@ enum powerpc_regset {
 #ifdef CONFIG_PPC_BOOK3S_64
         REGSET_TAR,             /* TAR register */
         REGSET_EBB,             /* EBB registers */
+        REGSET_PMR,             /* Performance Monitor Registers */
 #endif
 };
 
@@ -1957,6 +2027,11 @@ static const struct user_regset native_regsets[] = {
                 .size = sizeof(u64), .align = sizeof(u64),
                 .active = ebb_active, .get = ebb_get, .set = ebb_set
         },
+        [REGSET_PMR] = {
+                .core_note_type = NT_PPC_PMU, .n = ELF_NPMU,
+                .size = sizeof(u64), .align = sizeof(u64),
+                .active = pmu_active, .get = pmu_get, .set = pmu_set
+        },
 #endif
 };