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[PowerPC] Fix 32-bit ubldr calling convention

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Due to the way u-boot for 32-bit powerpc is compiled, the interrupt code
assumes that the GOT pointer (r30) on u-boot is always intact.

When making syscalls to u-boot, ensure that we have restored r30 like we
found it before we enable interrupts to prevent u-boot from crashing if a
timer interrupt was pending.

This fixes ubldr on e500 qemu (assuming you have recompiled qemu's u-boot
with API support!)

Reviewed by:	jhibbits
Sponsored by:	Tag1 Consulting, Inc.
Differential Revision:	https://reviews.freebsd.org/D23258
This commit is contained in:
Brandon Bergren 2020-01-19 04:13:19 +00:00
parent c7a19fd70a
commit a8614f0eec
1 changed files with 9 additions and 4 deletions
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13
stand/powerpc/uboot/start.S
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@ -38,10 +38,11 @@ _start:
lis %r11, uboot_address@ha
addi %r11, %r11, uboot_address@l
stw %r1, 0(%r11)
/* Save U-Boot's r14 */
/* Save U-Boot's r14 and r30 */
lis %r11, saved_regs@ha
addi %r11, %r11, saved_regs@l
stw %r14, 0(%r11)
stw %r30, 4(%r11)
/* Disable interrupts */
mfmsr %r11
andi. %r11, %r11, ~0x8000@l
@ -52,14 +53,16 @@ _start:
* syscall()
*/
ENTRY(syscall)
stwu %r1, -16(%r1)
stwu %r1, -32(%r1)
mflr %r0
stw %r14, 8(%r1)
stw %r0, 20(%r1)
/* Restore U-Boot's r14 */
stw %r30, 12(%r1)
stw %r0, 36(%r1)
/* Restore U-Boot's r14 and r30 */
lis %r11, saved_regs@ha
addi %r11, %r11, saved_regs@l
lwz %r14, 0(%r11)
lwz %r30, 4(%r11)
/* Enable interrupts */
mfmsr %r11
ori %r11, %r11, 0x8000@l
@ -79,6 +82,7 @@ ENTRY(syscall)
lwz %r0, 4(%r11)
mtlr %r0
lwz %r14, 8(%r1)
lwz %r30, 12(%r1)
mr %r1, %r11
blr
@ -90,5 +94,6 @@ GLOBAL(syscall_ptr)
.long 0
GLOBAL(saved_regs)
.long 0 /* R14 */
.long 0 /* R30 */
GLOBAL(uboot_address)
.long 0