Re: [Minios-devel] [PATCH v3 22/43] arm64: implement the __arch_switch_threads

[Huang Shijie <shijie.huang@xxxxxxx>]

On Thu, Apr 26, 2018 at 01:29:24PM +0100, Julien Grall wrote:
> Hi Shijie,
> 
> On 16/04/18 07:32, Huang Shijie wrote:
> >The __arch_switch_threads is used for switching the threads.
> >This patch implements it.
> >
> >Signed-off-by: Huang Shijie <shijie.huang@xxxxxxx>
> >---
> >  arch/arm/arm64/arm64.S | 38 ++++++++++++++++++++++++++++++++++++++
> >  include/arm/arm64/os.h |  4 ++++
> >  2 files changed, 42 insertions(+)
> >
> >diff --git a/arch/arm/arm64/arm64.S b/arch/arm/arm64/arm64.S
> >index fa3406f..5f55f99 100644
> >--- a/arch/arm/arm64/arm64.S
> >+++ b/arch/arm/arm64/arm64.S
> >@@ -1,5 +1,6 @@
> >  #include "asm.h"
> >  #include <arch_limits.h>
> >+#include <arm64/os.h>
> >  #include <arm64/pagetable.h>
> >  #include <arm64/traps.h>
> >  #include <xen/xen.h>
> >@@ -434,3 +435,40 @@ ENTRY(vector_table)
> >      vector_entry el0_fiq_invalid          /* FIQ 32-bit EL0         */
> >      vector_entry el0_error_invalid        /* Error 32-bit EL0       */
> >  END(vector_table)
> >+
> >+/*
> >+ * => x0 = &prev->sp
> >+ *    x1 = &next->sp
> >+ * <= switch to the next thread
> 
> Some documentation about the layout of the structure in memory would be
> useful.
okay. 
> 
> >+ */
> >+ENTRY(__arch_switch_threads)
> >+    /* Store the callee-saved registers to prev's struct thread */
> 
> AFAICT, you don't store the callee-saved registers in struct thread but on
> the stack. Am I right?
Yes.
I store them in the stack.

Thanks
Huang Shijie

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