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xtensa: userspace: swap page table earlier in xtensa_switch

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When switching page table and MPU enties, we need to call
corresponding functions via call4 which would move the register
window. So we need to do that earlier before we start saving
context into stack by manipulating stack pointer manually which
definitely would interfere with window spilling.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2025-03-24 15:15:26 -07:00 • committed by Benjamin Cabé
commit e0752c2938
1 changed files with 25 additions and 15 deletions
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40
arch/xtensa/core/xtensa_asm2_util.S
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@ -215,7 +215,32 @@ xtensa_arch_kernel_oops_epc:
.global xtensa_switch
.align 4
xtensa_switch:
#ifdef CONFIG_USERSPACE
entry a1, 32
s32i a4, a1, 0
s32i a5, a1, 4
s32i a6, a1, 8
s32i a7, a1, 12
/* Switch page tables */
rsr a6, ZSR_CPU
l32i a6, a6, ___cpu_t_current_OFFSET
#ifdef CONFIG_XTENSA_MMU
call4 xtensa_swap_update_page_tables
#endif
#ifdef CONFIG_XTENSA_MPU
call4 xtensa_mpu_map_write
#endif
l32i a7, a1, 12
l32i a6, a1, 8
l32i a5, a1, 4
l32i a4, a1, 0
#else
entry a1, 16
#endif
SPILL_ALL_WINDOWS
addi a1, a1, -___xtensa_irq_bsa_t_SIZEOF
@ -270,21 +295,6 @@ noflush:
l32i a3, a2, ___xtensa_irq_bsa_t_a3_OFFSET
s32i a1, a3, 0
#ifdef CONFIG_USERSPACE
/* Switch page tables */
rsr a6, ZSR_CPU
l32i a6, a6, ___cpu_t_current_OFFSET
#ifdef CONFIG_XTENSA_MMU
call4 xtensa_swap_update_page_tables
#endif
#ifdef CONFIG_XTENSA_MPU
call4 xtensa_mpu_map_write
#endif
l32i a2, a3, 0
l32i a2, a2, 0
#endif
/* Switch stack pointer and restore. The jump to
* _restore_context does not return as such, but we arrange
* for the restored "next" address to be immediately after for