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avoid 32-bit relocation to __BOOTLOADER_CONFIG #428

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merged 3 commits into from
Mar 14, 2024
Merged

avoid 32-bit relocation to __BOOTLOADER_CONFIG #428

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6652010
avoid 32-bit relocation to __BOOTLOADER_CONFIG
Freax13 Feb 21, 2024
b785b6d
add another level of indirection
Freax13 Feb 23, 2024
d0d10fe
don't call slice::as_ptr
Freax13 Mar 7, 2024
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10 changes: 7 additions & 3 deletions api/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -120,13 +120,17 @@ macro_rules! entry_point {
config.serialize()
};

// Workaround for https://github.com/rust-osdev/bootloader/issues/427
static __BOOTLOADER_CONFIG_REF: &[u8; $crate::BootloaderConfig::SERIALIZED_LEN] =
&__BOOTLOADER_CONFIG;

#[export_name = "_start"]
pub extern "C" fn __impl_start(boot_info: &'static mut $crate::BootInfo) -> ! {
// validate the signature of the program entry point
let f: fn(&'static mut $crate::BootInfo) -> ! = $path;

// ensure that the config is used so that the linker keeps it
$crate::__force_use(&__BOOTLOADER_CONFIG);
$crate::__force_use(&__BOOTLOADER_CONFIG_REF);

f(boot_info)
}
Expand All @@ -135,7 +139,7 @@ macro_rules! entry_point {
}

#[doc(hidden)]
pub fn __force_use(slice: &[u8]) {
let force_use = slice.as_ptr() as usize;
pub fn __force_use(slice: &&[u8; BootloaderConfig::SERIALIZED_LEN]) {
let force_use = slice as *const _ as usize;
unsafe { core::arch::asm!("add {0}, 0", in(reg) force_use, options(nomem, nostack)) };
}