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| author | Miquel Sabaté Solà <mikisabate@gmail.com> | 2024-12-04 14:35:50 +0100 |
|---|---|---|
| committer | Miquel Sabaté Solà <mikisabate@gmail.com> | 2024-12-04 14:35:50 +0100 |
| commit | 4c25981400e9d6d7c15df70dac32b6c8819b77a5 (patch) | |
| tree | 69ffdb0c5548aa2b11b6ba8468b6b34fb9a9eaee | |
| parent | ad072dbf39036eaeb2879bd39f5195175d8b1280 (diff) | |
| download | fbos-4c25981400e9d6d7c15df70dac32b6c8819b77a5.tar.gz fbos-4c25981400e9d6d7c15df70dac32b6c8819b77a5.zip | |
Re-use the halting loop also for the main hart
The halting in secondary harts should not be treated too differently as
with the (unlikely) scenario that the main function quits. Hence, merge
the code in both cases.
Moreover, we do not really need to to initialize the values of most
registers, as they will be explicitely set when needed anyways.
Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>
| -rw-r--r-- | kernel/head.S | 52 |
1 files changed, 15 insertions, 37 deletions
diff --git a/kernel/head.S b/kernel/head.S index b175b89..638e5e8 100644 --- a/kernel/head.S +++ b/kernel/head.S @@ -69,46 +69,17 @@ _start_kernel: la a3, hart_lottery li a2, 1 amoadd.w a3, a2, (a3) - beqz a3, .Lhart_proceed -.Lhart_wait: - wfi - j .Lhart_wait + bnez a3, .Lhart_wait -.Lhart_proceed: // Store the hart id as we will tamper with the 'a0' register later when // performing the call to `start_kernel`. la a3, hart_id sw a0, 0(a3) - // Reset all registers except ra, a0, a1. - li sp, 0 + // Explicitely nullify the 'gp' and 'sscratch' registers, as they are a bit + // special but we are not using them. For the rest of the registers, we + // explicitely do not care to reset them. li gp, 0 - li tp, 0 - li t0, 0 - li t1, 0 - li t2, 0 - li s0, 0 - li s1, 0 - li a2, 0 - li a3, 0 - li a4, 0 - li a5, 0 - li a6, 0 - li a7, 0 - li s2, 0 - li s3, 0 - li s4, 0 - li s5, 0 - li s6, 0 - li s7, 0 - li s8, 0 - li s9, 0 - li s10, 0 - li s11, 0 - li t3, 0 - li t4, 0 - li t5, 0 - li t6, 0 csrw sscratch, 0 // Point 'tp' to the init task. The 'tp' register will always point to the @@ -116,7 +87,7 @@ _start_kernel: // printing out messages. la tp, tasks - // Point 'sp' the our general stack. + // Point 'sp' the our global stack. See fbos/sched.h for more details. la sp, stack + STACK_SIZE // The `start_kernel` function requires an argument to be passed, which is @@ -127,6 +98,13 @@ _start_kernel: // Start the kernel. tail start_kernel - // We really shouldn't reach this point, but just in case, just loop - // infinitely here. - j . + // We really shouldn't reach this point. If so, at least mask again all + // interrupts, flush the instruction cache and halt the current hart. + csrw sie, zero + csrw sip, zero + fence.i + + // This is where harts come to die :) +.Lhart_wait: + wfi + j .Lhart_wait |