Commit-ID: 6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc Gitweb: http://git.kernel.org/tip/6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc Author: Dave Hansen <dave.hansen@xxxxxxxxx> AuthorDate: Tue, 4 Oct 2016 09:38:57 -0700 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Wed, 5 Oct 2016 10:34:55 +0200 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@xxxxxxxxx> Cc: Dave Hansen <dave@xxxxxxxx> Cc: linux-doc@xxxxxxxxxxxxxxx Cc: corbet@xxxxxxx Link: http://lkml.kernel.org/r/20161004163857.71E0D6F6@xxxxxxxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- Documentation/x86/protection-keys.txt | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/Documentation/x86/protection-keys.txt b/Documentation/x86/protection-keys.txt index 6da7689..b643045 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. -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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