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Clean up the arm64 fork_trampoline

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When exiting to userspace the code is similar to the restore_registers
macro in exception.S. Rework it to remove most of the non-style
differences.

Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Andrew Turner 2021-08-09 10:03:57 +00:00
parent d9d59bb1af
commit 1791a628a1
1 changed files with 16 additions and 22 deletions
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38
sys/arm64/arm64/swtch.S
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@ -213,7 +213,21 @@ ENTRY(fork_trampoline)
mov fp, #0 /* Stack traceback stops here. */
bl _C_LABEL(fork_exit)
/* Restore the registers other than x0 and x1 */
/*
* Disable interrupts to avoid
* overwriting spsr_el1 and sp_el0 by an IRQ exception.
*/
msr daifset, #10
/* Restore sp, lr, elr, and spsr */
ldp x18, lr, [sp, #TF_SP]
ldp x10, x11, [sp, #TF_ELR]
msr sp_el0, x18
msr spsr_el1, x11
msr elr_el1, x10
/* Restore the CPU registers */
ldp x0, x1, [sp, #TF_X + 0 * 8]
ldp x2, x3, [sp, #TF_X + 2 * 8]
ldp x4, x5, [sp, #TF_X + 4 * 8]
ldp x6, x7, [sp, #TF_X + 6 * 8]
@ -222,33 +236,13 @@ ENTRY(fork_trampoline)
ldp x12, x13, [sp, #TF_X + 12 * 8]
ldp x14, x15, [sp, #TF_X + 14 * 8]
ldp x16, x17, [sp, #TF_X + 16 * 8]
ldr x19, [sp, #TF_X + 19 * 8]
ldp x18, x19, [sp, #TF_X + 18 * 8]
ldp x20, x21, [sp, #TF_X + 20 * 8]
ldp x22, x23, [sp, #TF_X + 22 * 8]
ldp x24, x25, [sp, #TF_X + 24 * 8]
ldp x26, x27, [sp, #TF_X + 26 * 8]
ldp x28, x29, [sp, #TF_X + 28 * 8]
/*
* Disable interrupts to avoid
* overwriting spsr_el1 and sp_el0 by an IRQ exception.
*/
msr daifset, #2
/* Restore sp and lr */
ldp x0, x1, [sp, #TF_SP]
msr sp_el0, x0
mov lr, x1
/* Restore elr and spsr */
ldp x0, x1, [sp, #TF_ELR]
msr elr_el1, x0
msr spsr_el1, x1
/* Finally x0 and x1 */
ldp x0, x1, [sp, #TF_X + 0 * 8]
ldr x18, [sp, #TF_X + 18 * 8]
/*
* No need for interrupts reenabling since PSR
* will be set to the desired value anyway.