Messages in this thread | | | Date | Mon, 7 Sep 2015 15:56:47 +0100 | From | Mark Rutland <> | Subject | Re: [RFC PATCH 1/3] arm64: entry: Remove unnecessary calculation for S_SP in EL1h |
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On Fri, Sep 04, 2015 at 03:23:05PM +0100, Jungseok Lee wrote: > Under EL1h, S_SP data is not seen in kernel_exit. Thus, x21 calculation > is not needed in kernel_entry. Currently, S_SP information is vaild only > when sp_el0 is used.
I don't think this is true. The generic BUG implementation will grab the saved SP from the pt_regs, and with this change we'll report whatever happened to be in x21 instead.
> Signed-off-by: Jungseok Lee <jungseoklee85@gmail.com> > --- > arch/arm64/kernel/entry.S | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S > index e163518..d23ca0d 100644 > --- a/arch/arm64/kernel/entry.S > +++ b/arch/arm64/kernel/entry.S > @@ -91,8 +91,6 @@ > get_thread_info tsk // Ensure MDSCR_EL1.SS is clear, > ldr x19, [tsk, #TI_FLAGS] // since we can unmask debug > disable_step_tsk x19, x20 // exceptions when scheduling. > - .else > - add x21, sp, #S_FRAME_SIZE > .endif > mrs x22, elr_el1 > mrs x23, spsr_el1
Immediately after this we do:
stp lr, x21, [sp, #S_LR]
To store the LR and SP to the pt_regs which bug_handler would use.
Am I missing smoething?
Thanks, Mark.
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