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Subject[PATCH v9 22/51] powerpc/ptrace: Add memory protection key regset
Date
From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>

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>
---
arch/powerpc/include/asm/pkeys.h | 5 +++
arch/powerpc/include/uapi/asm/elf.h | 1 +
arch/powerpc/kernel/ptrace.c | 66 +++++++++++++++++++++++++++++++++++
arch/powerpc/kernel/traps.c | 7 ++++
include/uapi/linux/elf.h | 1 +
5 files changed, 80 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
index 3437a50..9ee4731 100644
--- a/arch/powerpc/include/asm/pkeys.h
+++ b/arch/powerpc/include/asm/pkeys.h
@@ -213,6 +213,11 @@ static inline int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
return __arch_set_user_pkey_access(tsk, pkey, init_val);
}

+static inline bool arch_pkeys_enabled(void)
+{
+ return !static_branch_likely(&pkey_disabled);
+}
+
static inline void pkey_mm_init(struct mm_struct *mm)
{
if (static_branch_likely(&pkey_disabled))
diff --git a/arch/powerpc/include/uapi/asm/elf.h b/arch/powerpc/include/uapi/asm/elf.h
index 5f201d4..860c592 100644
--- a/arch/powerpc/include/uapi/asm/elf.h
+++ b/arch/powerpc/include/uapi/asm/elf.h
@@ -97,6 +97,7 @@
#define ELF_NTMSPRREG 3 /* include tfhar, tfiar, texasr */
#define ELF_NEBB 3 /* includes ebbrr, ebbhr, bescr */
#define ELF_NPMU 5 /* includes siar, sdar, sier, mmcr2, mmcr0 */
+#define ELF_NPKEY 3 /* includes amr, iamr, uamor */

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 f52ad5b..3718a04 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>
@@ -1775,6 +1776,61 @@ 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.
*/
@@ -1809,6 +1865,9 @@ 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[] = {
@@ -1914,6 +1973,13 @@ enum powerpc_regset {
.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 = {
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index ed1c39b..f449dc5 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -291,6 +291,13 @@ void _exception_pkey(int signr, struct pt_regs *regs, int code, unsigned long ad
local_irq_enable();

current->thread.trap_nr = code;
+
+ /*
+ * Save all the pkey registers AMR/IAMR/UAMOR. Eg: Core dumps need
+ * to capture the content, if the task gets killed.
+ */
+ thread_pkey_regs_save(&current->thread);
+
memset(&info, 0, sizeof(info));
info.si_signo = signr;
info.si_code = code;
diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
index c58627c..c017818 100644
--- a/include/uapi/linux/elf.h
+++ b/include/uapi/linux/elf.h
@@ -396,6 +396,7 @@
#define NT_PPC_TM_CTAR 0x10d /* TM checkpointed Target Address Register */
#define NT_PPC_TM_CPPR 0x10e /* TM checkpointed Program Priority Register */
#define NT_PPC_TM_CDSCR 0x10f /* TM checkpointed Data Stream Control Register */
+#define NT_PPC_PKEY 0x110 /* Memory Protection Keys registers */
#define NT_386_TLS 0x200 /* i386 TLS slots (struct user_desc) */
#define NT_386_IOPERM 0x201 /* x86 io permission bitmap (1=deny) */
#define NT_X86_XSTATE 0x202 /* x86 extended state using xsave */
--
1.7.1
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