powerpc/ptrace: Add memory protection key regset

The AMR/IAMR/UAMOR are part of the program context.
Allow it to be accessed via ptrace and through core files.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 66 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index aef08e579946..ca72d7391d40 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -35,6 +35,7 @@
 #include <linux/context_tracking.h>
 
 #include <linux/uaccess.h>
+#include <linux/pkeys.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/switch_to.h>
@@ -1787,6 +1788,61 @@ static int pmu_set(struct task_struct *target,
 	return ret;
 }
 #endif
+
+#ifdef CONFIG_PPC_MEM_KEYS
+static int pkey_active(struct task_struct *target,
+		       const struct user_regset *regset)
+{
+	if (!arch_pkeys_enabled())
+		return -ENODEV;
+
+	return regset->n;
+}
+
+static int pkey_get(struct task_struct *target,
+		    const struct user_regset *regset,
+		    unsigned int pos, unsigned int count,
+		    void *kbuf, void __user *ubuf)
+{
+	BUILD_BUG_ON(TSO(amr) + sizeof(unsigned long) != TSO(iamr));
+	BUILD_BUG_ON(TSO(iamr) + sizeof(unsigned long) != TSO(uamor));
+
+	if (!arch_pkeys_enabled())
+		return -ENODEV;
+
+	return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
+				   &target->thread.amr, 0,
+				   ELF_NPKEY * sizeof(unsigned long));
+}
+
+static int pkey_set(struct task_struct *target,
+		      const struct user_regset *regset,
+		      unsigned int pos, unsigned int count,
+		      const void *kbuf, const void __user *ubuf)
+{
+	u64 new_amr;
+	int ret;
+
+	if (!arch_pkeys_enabled())
+		return -ENODEV;
+
+	/* Only the AMR can be set from userspace */
+	if (pos != 0 || count != sizeof(new_amr))
+		return -EINVAL;
+
+	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
+				 &new_amr, 0, sizeof(new_amr));
+	if (ret)
+		return ret;
+
+	/* UAMOR determines which bits of the AMR can be set from userspace. */
+	target->thread.amr = (new_amr & target->thread.uamor) |
+		(target->thread.amr & ~target->thread.uamor);
+
+	return 0;
+}
+#endif /* CONFIG_PPC_MEM_KEYS */
+
 /*
  * These are our native regset flavors.
  */
@@ -1821,6 +1877,9 @@ enum powerpc_regset {
 	REGSET_EBB,		/* EBB registers */
 	REGSET_PMR,		/* Performance Monitor Registers */
 #endif
+#ifdef CONFIG_PPC_MEM_KEYS
+	REGSET_PKEY,		/* AMR register */
+#endif
 };
 
 static const struct user_regset native_regsets[] = {
@@ -1926,6 +1985,13 @@ static const struct user_regset native_regsets[] = {
 		.active = pmu_active, .get = pmu_get, .set = pmu_set
 	},
 #endif
+#ifdef CONFIG_PPC_MEM_KEYS
+	[REGSET_PKEY] = {
+		.core_note_type = NT_PPC_PKEY, .n = ELF_NPKEY,
+		.size = sizeof(u64), .align = sizeof(u64),
+		.active = pkey_active, .get = pkey_get, .set = pkey_set
+	},
+#endif
 };
 
 static const struct user_regset_view user_ppc_native_view = {