Messages in this thread | | | Date | Fri, 28 Aug 2015 06:50:32 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 01/11] x86, fpu: kill LWP support |
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* Dave Hansen <dave@sr71.net> wrote:
> > From: Dave Hansen <dave.hansen@linux.intel.com> > > LightWeight Profiling was evidently an AMD profiling feature that > we never got around to implementing. Remove the references to it. > > This patch is a *bit* worrisome becuase it will implicitly cause > 'struct xregs_state' to shrink. This effectively removes some > unused padding that we had in there. It might expose other bugs. > > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: x86@kernel.org > Cc: Borislav Petkov <bp@alien8.de> > Cc: Fenghua Yu <fenghua.yu@intel.com> > Cc: Tim Chen <tim.c.chen@linux.intel.com> > Cc: linux-kernel@vger.kernel.org > --- > > b/arch/x86/include/asm/fpu/types.h | 6 ------ > 1 file changed, 6 deletions(-) > > diff -puN arch/x86/include/asm/fpu/types.h~axe-lwp arch/x86/include/asm/fpu/types.h > --- a/arch/x86/include/asm/fpu/types.h~axe-lwp 2015-08-27 10:08:01.195617135 -0700 > +++ b/arch/x86/include/asm/fpu/types.h 2015-08-27 10:08:01.198617272 -0700 > @@ -132,11 +132,6 @@ struct ymmh_struct { > u8 ymmh_space[256]; > }; > > -/* We don't support LWP yet: */ > -struct lwp_struct { > - u8 reserved[128]; > -}; > - > /* Intel MPX support: */ > struct bndreg { > u64 lower_bound; > @@ -161,7 +156,6 @@ struct xstate_header { > > /* New processor state extensions should be added here: */ > #define XSTATE_RESERVE (sizeof(struct ymmh_struct) + \ > - sizeof(struct lwp_struct) + \ > sizeof(struct mpx_struct) )
Btw., now that we allocate all this dynamically and sanity-check that the CPU gives us, I'd suggest we remove the XSTATE_RESERVE define altogether, and any excess __reserved[] bytes from the xstate header:
struct xregs_state { struct fxregs_state i387; struct xstate_header header; u8 __reserved[XSTATE_RESERVE]; } __attribute__ ((packed, aligned (64)));
any latent bug this might trigger we want to fix.
Thanks,
Ingo
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