On February 26, 2016 9:34:27 AM PST, Dave Hansen <[email protected]> wrote: > >From: Dave Hansen <[email protected]> > >Stephen Rothwell reported: > > http://lkml.kernel.org/r/[email protected] > >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 <[email protected]> >Cc: Stephen Rothwell <[email protected]> >Cc: Andrew Morton <[email protected]> >Cc: Thomas Gleixner <[email protected]> >Cc: Ingo Molnar <[email protected]> >Cc: "H. Peter Anvin" <[email protected]> >Cc: Peter Zijlstra <[email protected]> >Cc: [email protected] >Cc: [email protected] >Cc: Helge Deller <[email protected]> >--- > > 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; > >_
__u64 is okay, "unsigned long" is really messy in the presence of 32-on-64 bit ABIs... -- Sent from my Android device with K-9 Mail. Please excuse brevity and formatting.
