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[libc] Cleanup startup/baremetal/arm/start.cpp #151532

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Merged
merged 1 commit into from
Aug 11, 2025
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[libc] Cleanup startup/baremetal/arm/start.cpp #151532

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51 changes: 27 additions & 24 deletions libc/startup/baremetal/arm/start.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
//
//===----------------------------------------------------------------------===//

#include "hdr/stdint_proxy.h"
#include "src/__support/macros/config.h"
#include "src/stdlib/atexit.h"
#include "src/stdlib/exit.h"
Expand All @@ -14,8 +15,6 @@
#include "startup/baremetal/fini.h"
#include "startup/baremetal/init.h"

#include <stdint.h>

extern "C" {
int main(int argc, char **argv);
void _start();
Expand All @@ -31,7 +30,9 @@ extern uintptr_t __data_start[];
extern uintptr_t __data_size[];
extern uintptr_t __bss_start[];
extern uintptr_t __bss_size[];
} // extern "C"

namespace {
// Based on
// https://developer.arm.com/documentation/107565/0101/Use-case-examples/Generic-Information/What-is-inside-a-program-image-/Vector-table
void NMI_Handler() {}
Expand All @@ -49,35 +50,37 @@ void SysTick_Handler() {}
// to be zero and Cortex-M23 can require up to 10, so 1024-byte align the vector
// table.
using HandlerType = void (*)(void);
const HandlerType vector_table[]
__attribute__((section(".vectors"), aligned(1024), used)) = {
(HandlerType)&__stack, // SP
_start, // Reset
NMI_Handler, // NMI Handler
HardFault_Handler, // Hard Fault Handlerß
MemManage_Handler, // MPU Fault Han`dler
BusFault_Handler, // Bus Fault Handler
UsageFault_Handler, // Usage Fault Handler
0, // Reserved
0, // Reserved
0, // Reserved
0, // Reserved
SVC_Handler, // SVC Handler
DebugMon_Handler, // Debug Monitor Handler
0, // Reserved
PendSV_Handler, // PendSV Handler
SysTick_Handler, // SysTick Handler
// Unused
[[gnu::section(".vectors"), gnu::aligned(1024), gnu::used]]
const HandlerType vector_table[] = {
reinterpret_cast<HandlerType>(&__stack), // SP
_start, // Reset
NMI_Handler, // NMI Handler
HardFault_Handler, // Hard Fault Handlerß
MemManage_Handler, // MPU Fault Han`dler
BusFault_Handler, // Bus Fault Handler
UsageFault_Handler, // Usage Fault Handler
0, // Reserved
0, // Reserved
0, // Reserved
0, // Reserved
SVC_Handler, // SVC Handler
DebugMon_Handler, // Debug Monitor Handler
0, // Reserved
PendSV_Handler, // PendSV Handler
SysTick_Handler, // SysTick Handler
// Unused
};
} // extern "C"
} // namespace

namespace LIBC_NAMESPACE_DECL {
[[noreturn]] void do_start() {
// FIXME: set up the QEMU test environment

// Perform the equivalent of scatterloading
LIBC_NAMESPACE::memcpy(__data_start, __data_source, (uintptr_t)__data_size);
LIBC_NAMESPACE::memset(__bss_start, '\0', (uintptr_t)__bss_size);
LIBC_NAMESPACE::memcpy(__data_start, __data_source,
reinterpret_cast<uintptr_t>(__data_size));
LIBC_NAMESPACE::memset(__bss_start, '\0',
reinterpret_cast<uintptr_t>(__bss_size));
__libc_init_array();

_platform_init();
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