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o Keep running on U-Boot's stack.

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o  Disable interrupts while not running U-Boot code. We clobber
   registers that the U-Boot interrupt handlers assume to be
   fixed as per the U-Boot register usage. At this time this only
   applies to r14. U-Boot uses r2 now for what they used r29 for.
   After we restore r14 in preparation of doing the syscall, we
   re-enable interrupts. When we return from the syscall, we
   disable interrupts and restore the callee-saved r14.
This commit is contained in:
Marcel Moolenaar 2008-02-23 18:42:53 +00:00
parent f673ad04f5
commit 0f5615e325
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=176486
1 changed files with 23 additions and 21 deletions
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44
sys/boot/powerpc/uboot/start.S
View file

@ -28,23 +28,24 @@
#include <machine/asm.h>
#define STACK_SIZE 8192
/*
* Entry point to the loader that U-Boot passes control to.
*/
.text
.globl _start
.text
.globl _start
_start:
/* Fix up a stack */
lis %r1, stack@ha
addi %r1, %r1, stack@l
addi %r1, %r1, (STACK_SIZE - 32)
/* Save U-Boot's r14 and r29 */
/* Hint where to look for the API signature */
lis %r11, uboot_address@ha
addi %r11, %r11, uboot_address@l
stw %r2, 0(%r11)
/* Save U-Boot's r14 */
lis %r11, saved_regs@ha
addi %r11, %r11, saved_regs@l
stw %r14, 0(%r11)
stw %r29, 4(%r11)
/* Disable interrupts */
mfmsr %r11
andi. %r11, %r11, ~0x8000@l
mtmsr %r11
b main
/*
@ -54,25 +55,30 @@ ENTRY(syscall)
stwu %r1, -16(%r1)
mflr %r0
stw %r14, 8(%r1)
stw %r29, 12(%r1)
stw %r0, 20(%r1)
/* Restore U-Boot's r14 and r29 */
/* Restore U-Boot's r14 */
lis %r11, saved_regs@ha
addi %r11, %r11, saved_regs@l
lwz %r14, 0(%r11)
lwz %r29, 4(%r11)
/* Call into u-Boot */
/* Enable interrupts */
mfmsr %r11
ori %r11, %r11, 0x8000@l
mtmsr %r11
/* Call into U-Boot */
lis %r11, syscall_ptr@ha
addi %r11, %r11, syscall_ptr@l
lwz %r11, 0(%r11)
mtctr %r11
bctrl
/* Disable interrupts */
mfmsr %r11
andi. %r11, %r11, ~0x8000@l
mtmsr %r11
/* Epilogue */
lwz %r11, 0(%r1)
lwz %r0, 4(%r11)
mtlr %r0
lwz %r14, 8(%r1)
lwz %r29, 12(%r1)
mr %r1, %r11
blr
@ -80,13 +86,9 @@ ENTRY(syscall)
* Data section
*/
.data
.align 4
stack:
.space STACK_SIZE
GLOBAL(syscall_ptr)
.long 0
GLOBAL(saved_regs)
.long 0 /* R14 */
.long 0 /* R29 */
GLOBAL(uboot_address)
.long 0