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| Started by | Dave Hansen <dave@sr71.net> |
|---|---|
| First post | 2016-10-04 18:40 +0200 |
| Last post | 2016-10-05 10:50 +0200 |
| Articles | 2 — 2 participants |
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[PATCH] x86/pkeys: Update documentation Dave Hansen <dave@sr71.net> - 2016-10-04 18:40 +0200
[tip:mm/pkeys] x86/pkeys: Update documentation tip-bot for Dave Hansen <tipbot@zytor.com> - 2016-10-05 10:50 +0200
| From | Dave Hansen <dave@sr71.net> |
|---|---|
| Date | 2016-10-04 18:40 +0200 |
| Subject | [PATCH] x86/pkeys: Update documentation |
| Message-ID | <soAV4-5f3-23@gated-at.bofh.it> |
From: Dave Hansen <dave.hansen@intel.com> 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: x86@kernel.org Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org --- b/Documentation/x86/protection-keys.txt | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff -puN Documentation/x86/protection-keys.txt~pkeys-docfix Documentation/x86/protection-keys.txt --- a/Documentation/x86/protection-keys.txt~pkeys-docfix 2016-10-04 09:31:01.361928429 -0700 +++ b/Documentation/x86/protection-keys.txt 2016-10-04 09:32:39.142383585 -0700 @@ -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. _
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| From | tip-bot for Dave Hansen <tipbot@zytor.com> |
|---|---|
| Date | 2016-10-05 10:50 +0200 |
| Subject | [tip:mm/pkeys] x86/pkeys: Update documentation |
| Message-ID | <soQ3L-6QO-9@gated-at.bofh.it> |
| In reply to | #1495514 |
Commit-ID: 6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc Gitweb: http://git.kernel.org/tip/6679dac513fd612f34d3a3d99d7b84ed6d5eb5cc Author: Dave Hansen <dave.hansen@intel.com> AuthorDate: Tue, 4 Oct 2016 09:38:57 -0700 Committer: Thomas Gleixner <tglx@linutronix.de> 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@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> --- 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.
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