diff options
| author | Dave Hansen <dave.hansen@linux.intel.com> | 2016-02-12 13:02:36 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-02-18 19:46:32 +0100 |
| commit | 8459429693395ca9e8d18101300b120ad9171795 (patch) | |
| tree | 56a67afee6292c137696a31dabe873777304adb8 /include/linux/pkeys.h | |
| parent | b8b9b6ba9dec3f155c7555cb208ba4078e97aedb (diff) | |
x86/mm/pkeys: Allow kernel to modify user pkey rights register
The Protection Key Rights for User memory (PKRU) is a 32-bit
user-accessible register. It contains two bits for each
protection key: one to write-disable (WD) access to memory
covered by the key and another to access-disable (AD).
Userspace can read/write the register with the RDPKRU and WRPKRU
instructions. But, the register is saved and restored with the
XSAVE family of instructions, which means we have to treat it
like a floating point register.
The kernel needs to write to the register if it wants to
implement execute-only memory or if it implements a system call
to change PKRU.
To do this, we need to create a 'pkru_state' buffer, read the old
contents in to it, modify it, and then tell the FPU code that
there is modified data in there so it can (possibly) move the
buffer back in to the registers.
This uses the fpu__xfeature_set_state() function that we defined
in the previous patch.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210236.0BE13217@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/pkeys.h')
| -rw-r--r-- | include/linux/pkeys.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/pkeys.h b/include/linux/pkeys.h index 55e465f93a28..fc325b367bd0 100644 --- a/include/linux/pkeys.h +++ b/include/linux/pkeys.h @@ -4,6 +4,11 @@ #include <linux/mm_types.h> #include <asm/mmu_context.h> +#define PKEY_DISABLE_ACCESS 0x1 +#define PKEY_DISABLE_WRITE 0x2 +#define PKEY_ACCESS_MASK (PKEY_DISABLE_ACCESS |\ + PKEY_DISABLE_WRITE) + #ifdef CONFIG_ARCH_HAS_PKEYS #include <asm/pkeys.h> #else /* ! CONFIG_ARCH_HAS_PKEYS */ |