| Message ID | 1441376587-12979-2-git-send-email-jungseoklee85@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 04/09/15 15:23, 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. > > Signed-off-by: Jungseok Lee <jungseoklee85@gmail.com> > 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 > This sp value gets written to the struct pt_regs that is built on the stack, and passed to the fault handlers, see 'el1_sp_pc' in kernel/entry.S, which goes on to call do_sp_pc_abort() which prints this value out. (Other fault handlers may make decisions based on this value). It should be present and correct. Thanks, James
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.
On Sep 7, 2015, at 11:56 PM, Mark Rutland wrote: Hi Mark, > 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? No, You're right. As James mentioned, x21 is used in do_sp_pc_abort. Thanks for the comment. Best Regards Jungseok Lee
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
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. Signed-off-by: Jungseok Lee <jungseoklee85@gmail.com> --- arch/arm64/kernel/entry.S | 2 -- 1 file changed, 2 deletions(-)