Merge tag 'cris-for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jesper...

[cascardo/linux.git] / Documentation / x86 / protection-keys.txt

diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.txt
index 6da7689..b643045 100644 (file)
--- 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.