Messages in this thread | | | Date | Tue, 21 Feb 2012 14:26:05 +0000 | From | "Jan Beulich" <> | Subject | Re: [PATCH] x86-64: Fix CFI data for common_interrupt |
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>>> On 21.02.12 at 15:06, Mark Wielaard <mjw@redhat.com> wrote: > Commit eab9e6 "x86-64: Fix CFI data for interrupt frames" introduced > a DW_CFA_def_cfa_expression in the SAVE_ARGS_IRQ macro. To later define > the CFA using a simple register+offset rule both register and offset > need to be supplied. Just using CFI_DEF_CFA_REGISTER leaves the offset > undefined. So use CFI_DEF_CFA with reg+off explicitly at the end of > common_interrupt.
NAK, unless you can prove a path via which the offset will remain unset until hitting a CFI_DEF_CFA_REGISTER. And if you indeed found such a path, the entry point of the path is where the problem ought to be fixed.
Are you perhaps thinking that .cfi_def_cfa_register invalidates the offset in any way? That, to my knowledge, isn't the case, it just replaces the CFA register with the one specified, leaving the offset unchanged.
Jan
> Signed-off-by: Mark Wielaard <mjw@redhat.com> > --- > arch/x86/kernel/entry_64.S | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S > index 3fe8239..e00ef55 100644 > --- a/arch/x86/kernel/entry_64.S > +++ b/arch/x86/kernel/entry_64.S > @@ -813,7 +813,7 @@ ret_from_intr: > > /* Restore saved previous stack */ > popq %rsi > - CFI_DEF_CFA_REGISTER rsi > + CFI_DEF_CFA rsi,0 /* needed after def_cfa_expression */ > leaq ARGOFFSET-RBP(%rsi), %rsp > CFI_DEF_CFA_REGISTER rsp > CFI_ADJUST_CFA_OFFSET RBP-ARGOFFSET > -- > 1.7.7.6
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