From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Stephen Rothwell reported: http://lkml.kernel.org/r/20160226164406.065a1ffc@xxxxxxxxxxxxxxxx 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 'unsigned long'. The long 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. This also has the advantage that it allows existing 64-bit userspace to keep working without modification. 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@xxxxxxxxxxxxxxx> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: linux-next@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: Helge Deller <deller@xxxxxx> --- 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 2016-02-26 08:50:47.760659292 -0800 +++ b/include/uapi/asm-generic/siginfo.h 2016-02-26 08:52:08.591330838 -0800 @@ -98,7 +98,7 @@ typedef struct siginfo { void __user *_upper; } _addr_bnd; /* used when si_code=SEGV_PKUERR */ - u64 _pkey; + unsigned long _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 2016-02-26 08:51:50.357502608 -0800 +++ b/arch/mips/include/uapi/asm/siginfo.h 2016-02-26 08:51:55.206722873 -0800 @@ -93,7 +93,7 @@ typedef struct siginfo { void __user *_upper; } _addr_bnd; /* used when si_code=SEGV_PKUERR */ - u64 _pkey; + unsigned long _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 2016-02-26 08:51:50.413505152 -0800 +++ b/arch/ia64/include/uapi/asm/siginfo.h 2016-02-26 08:52:00.806977252 -0800 @@ -70,7 +70,7 @@ typedef struct siginfo { void __user *_upper; } _addr_bnd; /* used when si_code=SEGV_PKUERR */ - u64 _pkey; + unsigned long _pkey; }; } _sigfault; _ -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
