Eyck Jentzsch
1c9c00235d
This change updates the linker script and dependend wile so that thread local storage sections are properly supported and initailaized
111 lines
3.5 KiB
C
111 lines
3.5 KiB
C
/*
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Simple C++ startup routine to setup CRT
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SPDX-License-Identifier: Unlicense
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(https://five-embeddev.com/ | http://www.shincbm.com/)
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*/
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#include <stdint.h>
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#include <string.h>
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#include <picotls.h>
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#ifdef __cplusplus
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#define EXTERN_C extern "C"
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#else
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#define EXTERN_C extern
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#endif
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// Generic C function pointer.
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typedef void(*function_t)(void) ;
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// These symbols are defined by the linker script.
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// See linker.lds
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EXTERN_C uint8_t __bss_start;
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EXTERN_C uint8_t __bss_end;
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EXTERN_C const uint8_t __data_source;
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EXTERN_C uint8_t __data_start;
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EXTERN_C uint8_t __data_end;
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EXTERN_C const uint8_t __data_source;
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EXTERN_C uint8_t __tbss_start;
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EXTERN_C uintptr_t __tbss_size;
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EXTERN_C const uint8_t __tdata_source;
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EXTERN_C uint8_t __tls_base;
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EXTERN_C uintptr_t __tdata_size;
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EXTERN_C function_t __init_array_start;
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EXTERN_C function_t __init_array_end;
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EXTERN_C function_t __fini_array_start;
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EXTERN_C function_t __fini_array_end;
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// This function will be placed by the linker script according to the section
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// Raw function 'called' by the CPU with no runtime.
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EXTERN_C void _start(void) __attribute__ ((naked,section(".text.boot")));
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// Entry and exit points as C functions.
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EXTERN_C void _initialize(void) __attribute__ ((noreturn,section(".text.boot")));
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EXTERN_C void _exit(int exit_code) __attribute__ ((noreturn,noinline,weak));
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// Standard entry point, no arguments.
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extern int main(void);
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// The linker script will place this in the reset entry point.
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// It will be 'called' with no stack or C runtime configuration.
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// NOTE - this only supports a single hart.
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// tp will not be initialized
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void _start(void) {
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// Setup SP and GP
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// The locations are defined in the linker script
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__asm__ volatile (
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".option push;"
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// The 'norelax' option is critical here.
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// Without 'norelax' the global pointer will
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// be loaded relative to the global pointer!
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".option norelax;"
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"la gp, __global_pointer$;"
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".option pop;"
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"la sp, _sp;"
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"jal zero, _initialize;"
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: /* output: none %0 */
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: /* input: none */
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: /* clobbers: none */);
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// This point will not be executed, _initialize() will be called with no return.
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}
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// At this point we have a stack and global poiner, but no access to global variables.
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void _initialize(void) {
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// Init memory regions
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// Clear the .bss section (global variables with no initial values)
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memset((void*) &__bss_start, 0, (&__bss_end - &__bss_start));
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// Initialize the .data section (global variables with initial values)
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memcpy((void*)&__data_start, (const void*)&__data_source, (&__data_end - &__data_start));
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// Clear the .tbss section (thread local variables with no initial values)
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memset((void*) &__tbss_start, 0, __tbss_size);
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// Initialize the .tls section (thread local variables with initial values)
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memcpy((void*) &__tls_base, (const void*)&__tdata_source, __tdata_size);
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// Call constructors
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for (const function_t* entry=&__init_array_start;
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entry < &__init_array_end;
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++entry) {
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(*entry)();
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}
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#ifdef __THREAD_LOCAL_STORAGE
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_set_tls(__tls_base)
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#endif
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int rc = main();
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// Call destructors
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for (const function_t* entry=&__fini_array_start;
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entry < &__fini_array_end;
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++entry) {
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(*entry)();
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}
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_exit(rc);
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}
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// This should never be called. Busy loop with the CPU in idle state.
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void _exit(int exit_code) {
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(void)exit_code;
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// Halt
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while (1) {
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__asm__ volatile ("wfi");
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}
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} |