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authorDave Hansen <dave.hansen@linux.intel.com>2016-02-12 13:02:12 -0800
committerIngo Molnar <mingo@kernel.org>2016-02-18 09:32:42 +0100
commitcd0ea35ff5511cde299a61c21a95889b4a71464e (patch)
treedd9b696936ed60316607ed69a3484980d4609818 /include/uapi/asm-generic/siginfo.h
parentb376cd0256f86db3078409dc51963b315c7843d8 (diff)
signals, pkeys: Notify userspace about protection key faults
A protection key fault is very similar to any other access error. There must be a VMA, etc... We even want to take the same action (SIGSEGV) that we do with a normal access fault. However, we do need to let userspace know that something is different. We do this the same way what we did with SEGV_BNDERR with Memory Protection eXtensions (MPX): define a new SEGV code: SEGV_PKUERR. We add a siginfo field: si_pkey that reveals to userspace which protection key was set on the PTE that we faulted on. There is no other easy way for userspace to figure this out. They could parse smaps but that would be a bit cruel. We share space with in siginfo with _addr_bnd. #BR faults from MPX are completely separate from page faults (#PF) that trigger from protection key violations, so we never need both at the same time. Note that _pkey is a 64-bit value. The current hardware only supports 4-bit protection keys. We do this because there is _plenty_ of space in _sigfault and it is possible that future processors would support more than 4 bits of protection keys. The x86 code to actually fill in the siginfo is in the next patch. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Amanieu d'Antras <amanieu@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arnd Bergmann <arnd@arndb.de> 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: Oleg Nesterov <oleg@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Weinberger <richard@nod.at> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210212.3A9B83AC@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/uapi/asm-generic/siginfo.h')
-rw-r--r--include/uapi/asm-generic/siginfo.h17
1 files changed, 12 insertions, 5 deletions
diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
index 1e3552037a5a..90384d55225b 100644
--- a/include/uapi/asm-generic/siginfo.h
+++ b/include/uapi/asm-generic/siginfo.h
@@ -91,10 +91,15 @@ typedef struct siginfo {
int _trapno; /* TRAP # which caused the signal */
#endif
short _addr_lsb; /* LSB of the reported address */
- struct {
- void __user *_lower;
- void __user *_upper;
- } _addr_bnd;
+ union {
+ /* used when si_code=SEGV_BNDERR */
+ struct {
+ void __user *_lower;
+ void __user *_upper;
+ } _addr_bnd;
+ /* used when si_code=SEGV_PKUERR */
+ u64 _pkey;
+ };
} _sigfault;
/* SIGPOLL */
@@ -137,6 +142,7 @@ typedef struct siginfo {
#define si_addr_lsb _sifields._sigfault._addr_lsb
#define si_lower _sifields._sigfault._addr_bnd._lower
#define si_upper _sifields._sigfault._addr_bnd._upper
+#define si_pkey _sifields._sigfault._pkey
#define si_band _sifields._sigpoll._band
#define si_fd _sifields._sigpoll._fd
#ifdef __ARCH_SIGSYS
@@ -206,7 +212,8 @@ typedef struct siginfo {
#define SEGV_MAPERR (__SI_FAULT|1) /* address not mapped to object */
#define SEGV_ACCERR (__SI_FAULT|2) /* invalid permissions for mapped object */
#define SEGV_BNDERR (__SI_FAULT|3) /* failed address bound checks */
-#define NSIGSEGV 3
+#define SEGV_PKUERR (__SI_FAULT|4) /* failed protection key checks */
+#define NSIGSEGV 4
/*
* SIGBUS si_codes

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