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Subject[PATCH v9 26/51] powerpc: add sys_pkey_modify() system call
Date
sys_pkey_modify()  is   powerpc  specific  system  call.  It
enables the ability to modify *any* attribute of a key.

Since powerpc disallows modification of IAMR from user space
an application is unable to change a key's execute-attribute.

This system call helps accomplish the above.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
---
arch/powerpc/include/asm/systbl.h | 1 +
arch/powerpc/include/asm/unistd.h | 2 +-
arch/powerpc/include/uapi/asm/unistd.h | 1 +
arch/powerpc/kernel/entry_64.S | 9 +++++++++
arch/powerpc/mm/pkeys.c | 17 +++++++++++++++++
5 files changed, 29 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index d61f9c9..533cdc5 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h
@@ -392,3 +392,4 @@
SYSCALL(pkey_alloc)
SYSCALL(pkey_free)
SYSCALL(pkey_mprotect)
+PPC64ONLY(pkey_modify)
diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h
index daf1ba9..1e97086 100644
--- a/arch/powerpc/include/asm/unistd.h
+++ b/arch/powerpc/include/asm/unistd.h
@@ -12,7 +12,7 @@
#include <uapi/asm/unistd.h>


-#define NR_syscalls 387
+#define NR_syscalls 388

#define __NR__exit __NR_exit

diff --git a/arch/powerpc/include/uapi/asm/unistd.h b/arch/powerpc/include/uapi/asm/unistd.h
index 389c36f..318cd79 100644
--- a/arch/powerpc/include/uapi/asm/unistd.h
+++ b/arch/powerpc/include/uapi/asm/unistd.h
@@ -398,5 +398,6 @@
#define __NR_pkey_alloc 384
#define __NR_pkey_free 385
#define __NR_pkey_mprotect 386
+#define __NR_pkey_modify 387

#endif /* _UAPI_ASM_POWERPC_UNISTD_H_ */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 4a0fd4f..47c85f9 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -455,6 +455,15 @@ _GLOBAL(ppc_switch_endian)
bl sys_switch_endian
b .Lsyscall_exit

+_GLOBAL(ppc_pkey_modify)
+ bl save_nvgprs
+#ifdef CONFIG_PPC_MEM_KEYS
+ bl sys_pkey_modify
+#else
+ bl sys_ni_syscall
+#endif
+ b .Lsyscall_exit
+
_GLOBAL(ret_from_fork)
bl schedule_tail
REST_NVGPRS(r1)
diff --git a/arch/powerpc/mm/pkeys.c b/arch/powerpc/mm/pkeys.c
index 5047371..2612f61 100644
--- a/arch/powerpc/mm/pkeys.c
+++ b/arch/powerpc/mm/pkeys.c
@@ -420,3 +420,20 @@ bool arch_vma_access_permitted(struct vm_area_struct *vma, bool write,

return pkey_access_permitted(vma_pkey(vma), write, execute);
}
+
+long sys_pkey_modify(int pkey, unsigned long new_val)
+{
+ bool ret;
+ /* Check for unsupported init values */
+ if (new_val & ~PKEY_ACCESS_MASK)
+ return -EINVAL;
+
+ down_write(&current->mm->mmap_sem);
+ ret = mm_pkey_is_allocated(current->mm, pkey);
+ up_write(&current->mm->mmap_sem);
+
+ if (!ret)
+ return -EINVAL;
+
+ return __arch_set_user_pkey_access(current, pkey, new_val);
+}
--
1.7.1
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