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Diffstat (limited to 'arch/riscv/supervisor/hsm/head.S')
| -rw-r--r-- | arch/riscv/supervisor/hsm/head.S | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/arch/riscv/supervisor/hsm/head.S b/arch/riscv/supervisor/hsm/head.S new file mode 100644 index 0000000..e912b18 --- /dev/null +++ b/arch/riscv/supervisor/hsm/head.S @@ -0,0 +1,44 @@ +.global _start +.section .head.text + +_start: + // Start by simply disabling interrupts. + csrw sie, zero + csrw sip, zero + fence.i + + // Initialize the 'a4' register, which is going to be used for printing out + // the end message by the main hart. + li a4, 0 + + // Hart lottery! The main hart will win it, the rest will simply jump into + // .Lhalt. See hsm.c for more details. + la a3, hart_lottery + li a2, 1 + amoadd.w a3, a2, (a3) + bnez a3, .Lhalt + + // Setup a dummy stack and call the kernel. + la sp, _STACK_PTR + call start_kernel + + // We actually expect the main kernel routine to quit. Here we make the + // .Lhalt part of the code to print special messages for that case. + addi a4, a4, 1 + +.Lhalt: + // Increase the number of hart that lost the lottery. + la a3, hart_failed_lottery + li a2, 1 + amoadd.w zero, a2, (a3) + + // If it's the main hart that is bailing out, first print some final + // messages. + beqz a4, .Lend + call print_lottery + call end + + // Die Bart, die! +.Lend: + wfi + j .Lend |