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Cleaned up boot.S so it's clearer where the changes are from part9

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Adam Greenwood-Byrne 2021-02-22 11:28:55 +00:00
parent 56068acbb6
commit 75beaecccf
1 changed files with 49 additions and 42 deletions
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91
part10-multicore/boot.S
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@ -1,52 +1,59 @@
#define LOCAL_CONTROL 0xff800000 #define LOCAL_CONTROL 0xff800000
#define LOCAL_PRESCALER 0xff800008 #define LOCAL_PRESCALER 0xff800008
#define OSC_FREQ 54000000 #define OSC_FREQ 54000000
#define MAIN_STACK 0x400000 #define MAIN_STACK 0x400000
.section ".text.boot" .section ".text.boot" // Make sure the linker puts this at the start of the kernel image
.global _start // Execution starts here
.globl _start
_start: _start:
ldr x0, =LOCAL_CONTROL // Sort out the timer ldr x0, =LOCAL_CONTROL // Sort out the timer
str wzr, [x0] str wzr, [x0]
mov w1, 0x80000000 mov w1, 0x80000000
str w1, [x0, #(LOCAL_PRESCALER - LOCAL_CONTROL)] str w1, [x0, #(LOCAL_PRESCALER - LOCAL_CONTROL)]
ldr x0, =OSC_FREQ ldr x0, =OSC_FREQ
msr cntfrq_el0, x0 msr cntfrq_el0, x0
msr cntvoff_el2, xzr msr cntvoff_el2, xzr
mrs x6, mpidr_el1 // Check processor ID is zero (executing on main core), else hang
and x6, x6,#0xFF // Check processor id mrs x1, mpidr_el1
cbz x6, primary_cpu // Hang for all non-primary CPU and x1, x1, #3
cbz x1, 2f
adr x5, spin_cpu0 // We're not on the main core, so hang in an infinite wait loop
proc_hang: adr x5, spin_cpu0
wfe 1: wfe
ldr x4, [x5, x6, lsl #3] ldr x4, [x5, x1, lsl #3]
cbz x4, proc_hang cbz x4, 1b
ldr x1, =__test_stack // Get ourselves a fresh stack ldr x1, =__test_stack // Get ourselves a fresh stack
mov sp, x1 mov sp, x1
secondary_cpu:
mov x0, #0 mov x0, #0
mov x1, #0 mov x1, #0
mov x2, #0 mov x2, #0
mov x3, #0 mov x3, #0
br x4 br x4
b proc_hang b 1b
primary_cpu: 2: // We're on the main core!
ldr x1, =__bss_start
ldr w2, =__bss_size // Set stack to start somewhere safe
memzero: mov sp, #MAIN_STACK
cbz w2, startup
str xzr, [x1], #8 // Clean the BSS section
sub w2, w2, #1 ldr x1, =__bss_start // Start address
cbnz w2, memzero ldr w2, =__bss_size // Size of the section
startup: 3: cbz w2, 4f // Quit loop if zero
mov sp, #MAIN_STACK str xzr, [x1], #8
bl main sub w2, w2, #1
b proc_hang // should never come here cbnz w2, 3b // Loop if non-zero
// Jump to our main() routine in C (make sure it doesn't return)
4: bl main
// In case it does return, halt the master core too
b 1b
.ltorg .ltorg