From: Dave Hansen <dave@sr71•net>
To: linux-kernel@vger•kernel.org
Cc: Dave Hansen <dave@sr71•net>,
dave.hansen@linux•intel.com, sfr@canb•auug.org.au,
akpm@linux-foundation•org, tglx@linutronix•de, mingo@elte•hu,
hpa@zytor•com, peterz@infradead•org, linux-next@vger•kernel.org,
deller@gmx•de
Subject: [PATCH] [v3] x86, pkeys: fix siginfo ABI breakage from new field
Date: Mon, 29 Feb 2016 14:17:33 -0800 [thread overview]
Message-ID: <20160229221733.DC2C56B7@viggo.jf.intel.com> (raw)
This responds to the feedback from Ingo that we should be using
explicitly-sized types and fixes a typo in the patch description.
--
From: Dave Hansen <dave.hansen@linux•intel.com>
Stephen Rothwell reported:
http://lkml.kernel.org/r/20160226164406.065a1ffc@canb.auug.org.au
that the Memory Protection Keys patches from the tip tree broke
a build-time check on an ARM build because they changed the ABI
of siginfo.
A u64 was used for the protection key field in siginfo. When the
containing union was aligned, this u64 unioned nicely with the
two 'void *'s in _addr_bnd. But, on 32-bit, if the union was
unaligned, the u64 might grow the size of the union, breaking the
ABI for subsequent fields.
To fix this, we replace the u64 with an '__u32'. The __u32 is
guaranteed to union well with the pointers from _addr_bnd. It is
also plenty large enough to store the 16-bit pkey we have today
on x86.
I also shouldn't have been using a u64 in a userspace API to begin
with.
Fixes: cd0ea35ff551 ("signals, pkeys: Notify userspace about protection key faults")
Signed-off-by: Dave Hansen <dave.hansen@linux•intel.com>
Acked-by: Stehen Rothwell <sfr@canb•auug.org.au>
Cc: Andrew Morton <akpm@linux-foundation•org>
Cc: Thomas Gleixner <tglx@linutronix•de>
Cc: Ingo Molnar <mingo@elte•hu>
Cc: "H. Peter Anvin" <hpa@zytor•com>
Cc: Peter Zijlstra <peterz@infradead•org>
Cc: linux-next@vger•kernel.org
Cc: linux-kernel@vger•kernel.org
Cc: Helge Deller <deller@gmx•de>
---
b/arch/ia64/include/uapi/asm/siginfo.h | 2 +-
b/arch/mips/include/uapi/asm/siginfo.h | 2 +-
b/include/uapi/asm-generic/siginfo.h | 2 +-
3 files changed, 3 insertions(+), 3 deletions(-)
diff -puN include/uapi/asm-generic/siginfo.h~pkeys-101-fix-siginfo include/uapi/asm-generic/siginfo.h
--- a/include/uapi/asm-generic/siginfo.h~pkeys-101-fix-siginfo 2016-02-29 09:22:45.327228965 -0800
+++ b/include/uapi/asm-generic/siginfo.h 2016-02-29 09:22:45.333229241 -0800
@@ -98,7 +98,7 @@ typedef struct siginfo {
void __user *_upper;
} _addr_bnd;
/* used when si_code=SEGV_PKUERR */
- u64 _pkey;
+ __u32 _pkey;
};
} _sigfault;
diff -puN arch/mips/include/uapi/asm/siginfo.h~pkeys-101-fix-siginfo arch/mips/include/uapi/asm/siginfo.h
--- a/arch/mips/include/uapi/asm/siginfo.h~pkeys-101-fix-siginfo 2016-02-29 09:22:45.330229103 -0800
+++ b/arch/mips/include/uapi/asm/siginfo.h 2016-02-29 09:22:45.333229241 -0800
@@ -93,7 +93,7 @@ typedef struct siginfo {
void __user *_upper;
} _addr_bnd;
/* used when si_code=SEGV_PKUERR */
- u64 _pkey;
+ __u32 _pkey;
};
} _sigfault;
diff -puN arch/ia64/include/uapi/asm/siginfo.h~pkeys-101-fix-siginfo arch/ia64/include/uapi/asm/siginfo.h
--- a/arch/ia64/include/uapi/asm/siginfo.h~pkeys-101-fix-siginfo 2016-02-29 09:22:45.331229149 -0800
+++ b/arch/ia64/include/uapi/asm/siginfo.h 2016-02-29 09:22:45.333229241 -0800
@@ -70,7 +70,7 @@ typedef struct siginfo {
void __user *_upper;
} _addr_bnd;
/* used when si_code=SEGV_PKUERR */
- u64 _pkey;
+ __u32 _pkey;
};
} _sigfault;
_
next reply other threads:[~2016-02-29 22:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-29 22:17 Dave Hansen [this message]
2016-02-29 22:33 ` [PATCH] [v3] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell
2016-03-01 7:40 ` Ingo Molnar
2016-03-01 8:09 ` Ingo Molnar
2016-03-01 12:48 ` Dave Hansen
2016-03-01 9:39 ` Ingo Molnar
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