diff options
| author | Dave Hansen | 2016-10-04 09:38:57 -0700 |
|---|---|---|
| committer | Thomas Gleixner | 2016-10-05 10:34:55 +0200 |
| commit | 6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc (patch) | |
| tree | 86d7b892cbf634bc83bf2a9ab3619d7d5709de97 /Documentation/x86/protection-keys.txt | |
| parent | ba6d018e3d2f6a0fad58a668cadf66b2d1f80f59 (diff) | |
x86/pkeys: Update documentation
There are a few items that have gotten stale in the protection
keys documentation. The config option description only applied
to the execute-only support and is not accurate for the current
code. There was also a typo with the number of system calls. I
also wanted to call out that pkey_set() is not a kernel-provided
facility, and where to find an implementation.
Signed-off-by: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: linux-doc@vger.kernel.org
Cc: corbet@lwn.net
Link: http://lkml.kernel.org/r/20161004163857.71E0D6F6@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/x86/protection-keys.txt')
| -rw-r--r-- | Documentation/x86/protection-keys.txt | 14 |
1 files changed, 5 insertions, 9 deletions
diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.txt index 6da7689601d1..b64304540821 100644 --- a/Documentation/x86/protection-keys.txt +++ b/Documentation/x86/protection-keys.txt @@ -20,7 +20,7 @@ instruction fetches. =========================== Syscalls =========================== -There are 2 system calls which directly interact with pkeys: +There are 3 system calls which directly interact with pkeys: int pkey_alloc(unsigned long flags, unsigned long init_access_rights) int pkey_free(int pkey); @@ -52,6 +52,10 @@ is no longer in use: munmap(ptr, PAGE_SIZE); pkey_free(pkey); +(Note: pkey_set() is a wrapper for the RDPKRU and WRPKRU instructions. + An example implementation can be found in + tools/testing/selftests/x86/protection_keys.c) + =========================== Behavior =========================== The kernel attempts to make protection keys consistent with the @@ -79,11 +83,3 @@ with a read(): The kernel will send a SIGSEGV in both cases, but si_code will be set to SEGV_PKERR when violating protection keys versus SEGV_ACCERR when the plain mprotect() permissions are violated. - -=========================== Config Option =========================== - -This config option adds approximately 1.5kb of text. and 50 bytes of -data to the executable. A workload which does large O_DIRECT reads -of holes in XFS files was run to exercise get_user_pages_fast(). No -performance delta was observed with the config option -enabled or disabled. |