danielandClaude Fable 5
5db2bd4c7c
MontaukOS binaries could not use thread-local storage: the ELF loader ignored PT_TLS and no FS base was ever programmed, so any %fs access (initial-exec/local-exec TLS, e.g. libbfd's _Thread_local error state) page faulted at address 0. This is the kernel prerequisite for cc1plus/libstdc++ in the GCC port. ELF loader: parse PT_TLS and build the main thread's TLS block above the loaded image (x86-64 variant II ABI: block below the thread pointer, TP = base + align_up(memsz, align), .tdata copied from the template, .tbss zeroed, ABI self-pointer stored at [TP]). The template description is kept on the process for thread spawns. Scheduler: fsBase per thread, loaded into IA32_FS_BASE at every dispatch site through a per-CPU cache - TLS-free processes cost one MSR write per CPU ever, and userspace cannot desync the cache since CR4.FSGSBASE stays off. SYS_THREAD_SPAWN gives each new thread its own TLS block copied from the template (allocated from the process heap; reclaimed at process teardown). Ships tls-test.elf in the SDK (built by the devkit target): checks .tdata values, .tbss zeroing, and the %fs:0 self-pointer, exiting nonzero on failure. Boot-smoke verified; existing TLS-free programs are unaffected. Co-Authored-By: Claude Fable 5 <[email protected]>
38 lines
1.1 KiB
C
38 lines
1.1 KiB
C
/*
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* tls-test.c
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* Verifies the MontaukOS TLS runtime: PT_TLS loading, FS base,
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* .tdata initialization, .tbss zeroing, and the ABI self-pointer.
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* Built by the devkit target and shipped at 0:/sdk/bin/tls-test.elf.
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*/
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#include <stdio.h>
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#include <stdint.h>
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__thread int tls_int = 41;
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__thread char tls_str[32] = "montauk-tls";
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__thread int tls_bss[8]; /* .tbss, must arrive zeroed */
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int main(void) {
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int ok = 1;
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tls_int++;
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tls_bss[3] = 7;
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printf("tls_int = %d (want 42)\n", tls_int);
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printf("tls_str = %s (want montauk-tls)\n", tls_str);
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printf("tls_bss = %d,%d (want 0,7)\n", tls_bss[0], tls_bss[3]);
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if (tls_int != 42) ok = 0;
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if (tls_str[0] != 'm' || tls_str[10] != 's') ok = 0;
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if (tls_bss[0] != 0 || tls_bss[3] != 7) ok = 0;
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/* The thread pointer must hold a self-pointer at %fs:0. */
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uint64_t self;
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__asm__("mov %%fs:0, %0" : "=r"(self));
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printf("fs:0 self = 0x%lx\n", (unsigned long)self);
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if (self == 0) ok = 0;
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printf(ok ? "TLS OK\n" : "TLS BROKEN\n");
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return ok ? 0 : 1;
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}
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