powerpc/ptrace: Add memory protection key regset
authorThiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Fri, 19 Jan 2018 01:50:43 +0000 (17:50 -0800)
committerMichael Ellerman <mpe@ellerman.id.au>
Sat, 20 Jan 2018 11:59:06 +0000 (22:59 +1100)
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>
arch/powerpc/include/asm/pkeys.h
arch/powerpc/include/uapi/asm/elf.h
arch/powerpc/kernel/ptrace.c
arch/powerpc/kernel/traps.c
include/uapi/linux/elf.h

index 2298771b066b16fcde0de2c1f150b1c86f7ddb6f..c3cbad824e5a9ad839f80b63ec4fc3d51f63a7c7 100644 (file)
@@ -202,6 +202,11 @@ 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);
+}
+
 extern void pkey_mm_init(struct mm_struct *mm);
 extern void thread_pkey_regs_save(struct thread_struct *thread);
 extern void thread_pkey_regs_restore(struct thread_struct *new_thread,
index 5f201d40bcca64f2e1eb48b337d84714b53fe53e..860c59291bfcd62108e1ffbe30d4a109d856645d 100644 (file)
@@ -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];
index aef08e57994672c213a83b3694f923391a2d8842..ca72d7391d404f9acb4dee60b800a2b1edd2f03c 100644 (file)
@@ -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 = {
index 4b1a8e2ec02369f853755616301099389fb58f86..122a3c883f4ef791110ef0a9f873f7c60d2be2c2 100644 (file)
@@ -292,6 +292,13 @@ void _exception_pkey(int signr, struct pt_regs *regs, int code,
                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;
index bb6836986200d61d4c01fc24304966b54bbd9f94..3bf73fb58045da56562c5c790f80aed860827672 100644 (file)
@@ -396,6 +396,7 @@ typedef struct elf64_shdr {
 #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 */