Robert Allan JamesandClaude Opus 5.5
8409e376cf
- New sk_percpu_t { self, core_id, current_vm }, reached via GS base
(amd64, %gs:0), TPIDR_EL1 (aarch64), tp (riscv64). Boot core's block is
one static object installed right after arch_early_init(); secondary
cores' blocks come with MC-1.
- switch.c's global g_switch_current_vm is gone; current VM is
sk_percpu()->current_vm, re-read after resume in the context switch.
- Probe (removed): normal path and every heartbeat ISR found core 0's
block on all three ISAs (ISR ok 889/1877/1625, bad 0).
- Standard sequence on amd64/aarch64/riscv64: hashes unchanged from O-C,
G A=40 B=40, MINT/WIREBIND/USE ok, conservation true, 0 idle growth.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
90 lines
3.2 KiB
C
90 lines
3.2 KiB
C
/*
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StarForth — Steady-State Virtual Machine Runtime
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Copyright (c) 2023–2025 Robert A. James
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All rights reserved.
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This file is part of the StarForth project.
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Licensed under the StarForth License, Version 1.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at:
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https://github.com/star.4th@proton.me/StarForth/LICENSE.txt
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This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
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express or implied, including but not limited to the warranties of
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merchantability, fitness for a particular purpose, and noninfringement.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/**
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* percpu.h - Per-core state (FABRIC-3.10.8 Stage MC-0a).
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*
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* Each core owns one sk_percpu_t, reached through that ISA's per-CPU
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* register, so code running on a core -- including an interrupt handler --
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* finds its own block without a lookup:
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* - amd64: the GS base (IA32_GS_BASE); the block's first field points
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* back at itself, so `mov %gs:0` reads the pointer.
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* - aarch64: TPIDR_EL1 (reachable from EL2 as well, so either boot EL).
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* - riscv64: the tp register (the kernel owns it: no user mode, no TLS;
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* the trap entry never touches it).
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*
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* MC-0a: only the boot core exists, and its block is a single statically
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* allocated object (not a table of cores -- secondary cores' blocks are
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* allocated as they come online, MC-1). What moves in first is the switch
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* mechanism's "who is running on this core" (was switch.c's global
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* g_switch_current_vm).
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*/
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#ifndef STARKERNEL_PERCPU_H
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#define STARKERNEL_PERCPU_H
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#include <stdint.h>
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struct VM;
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typedef struct sk_percpu {
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struct sk_percpu *self; /* must stay first: amd64 reads it as %gs:0 */
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uint32_t core_id; /* 0 = the boot core (the system core, MC-R1) */
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struct VM *current_vm; /* who is running on this core (switch.c) */
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} sk_percpu_t;
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/* Installs the boot core's block in this core's per-CPU register. Call
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* once, as early as possible (kernel_main, straight after
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* arch_early_init(): on amd64 that reloads GS, which would reset the base). */
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void sk_percpu_boot_init(void);
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/* This core's block. Valid from sk_percpu_boot_init() on. */
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static inline sk_percpu_t *sk_percpu(void)
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{
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sk_percpu_t *p;
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#if defined(__x86_64__)
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__asm__ volatile ("movq %%gs:0, %0" : "=r"(p));
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#elif defined(__aarch64__)
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__asm__ volatile ("mrs %0, tpidr_el1" : "=r"(p));
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#elif defined(__riscv)
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__asm__ volatile ("mv %0, tp" : "=r"(p));
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#else
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#error "percpu.h: unsupported architecture"
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#endif
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return p;
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}
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/* Architecture hook: point this core's per-CPU register at `p`. */
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static inline void sk_percpu_install(sk_percpu_t *p)
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{
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#if defined(__x86_64__)
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uint64_t v = (uint64_t)(uintptr_t)p;
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__asm__ volatile ("wrmsr" : : "c"(0xC0000101u) /* IA32_GS_BASE */,
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"a"((uint32_t)v), "d"((uint32_t)(v >> 32)) : "memory");
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#elif defined(__aarch64__)
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__asm__ volatile ("msr tpidr_el1, %0" : : "r"(p) : "memory");
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#elif defined(__riscv)
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__asm__ volatile ("mv tp, %0" : : "r"(p) : "memory");
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#endif
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}
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#endif /* STARKERNEL_PERCPU_H */
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