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Merged
merged 19 commits into from
May 9, 2025
Merged

[libc][uefi] add crt1 #132150

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b12c594
[libc][uefi] add crt1
RossComputerGuy Mar 20, 2025
dee779f
[libc][uefi] drop mingw compat in crt0
RossComputerGuy Mar 20, 2025
7428fe0
[libc][uefi] update efi symbols in efi main
RossComputerGuy Mar 21, 2025
bf566bb
[libc][uefi] add status codes
RossComputerGuy Mar 21, 2025
40a26a0
[libc][uefi] fix Uefi.h install name
RossComputerGuy Mar 22, 2025
e5a4692
[libc][uefi] add errno and uefi status conversion
RossComputerGuy Mar 22, 2025
d963ce2
[libc][uefi] fix error, exit, and io OSUtil support compilation
RossComputerGuy Mar 22, 2025
4ccc169
[libc][uefi] get error codes working
RossComputerGuy Mar 22, 2025
65da577
[libc][uefi] fix review
RossComputerGuy Mar 27, 2025
553ec1b
[libc][uefi] fix formatting
RossComputerGuy Mar 27, 2025
6648c0c
[libc][uefi] use cpp::array for the error map
RossComputerGuy Apr 1, 2025
0596ada
[libc][uefi] use LIBC_INLINE in error
RossComputerGuy Apr 2, 2025
f87345a
[libc][uefi] add startup integration test
RossComputerGuy Apr 2, 2025
0a47352
[libc][uefi] use cpp::numeric_limits for UEFI_STATUS_ERRNO_MAP
RossComputerGuy Apr 2, 2025
ae46dfc
[libc][uefi] move uefi system table & image to app config
RossComputerGuy Apr 24, 2025
5e4c64f
[libc] fix formatting
RossComputerGuy Apr 24, 2025
74dd600
[libc][uefi] use constexpr for errno map
RossComputerGuy Apr 24, 2025
3aaccf0
Merge branch 'main' into feat/libc-uefi/start
RossComputerGuy May 1, 2025
b5dbce3
[libc][uefi] review adjustments
RossComputerGuy May 6, 2025
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46 changes: 46 additions & 0 deletions libc/startup/uefi/CMakeLists.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
function(add_startup_object name)
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I apparently missed that each of the targets currently has their own definition of this. Please add a todo referencing #133156 (the bug I've filed for this)

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Done

cmake_parse_arguments(
"ADD_STARTUP_OBJECT"
"ALIAS" # Option argument
"SRC" # Single value arguments
"DEPENDS;COMPILE_OPTIONS" # Multi value arguments
${ARGN}
)

get_fq_target_name(${name} fq_target_name)
if(ADD_STARTUP_OBJECT_ALIAS)
get_fq_deps_list(fq_dep_list ${ADD_STARTUP_OBJECT_DEPENDS})
add_library(${fq_target_name} ALIAS ${fq_dep_list})
return()
endif()

add_object_library(
${name}
SRCS ${ADD_STARTUP_OBJECT_SRC}
COMPILE_OPTIONS ${ADD_STARTUP_OBJECT_COMPILE_OPTIONS}
${ADD_STARTUP_OBJECT_UNPARSED_ARGUMENTS}
DEPENDS ${ADD_STARTUP_OBJECT_DEPENDS}
)
set_target_properties(
${fq_target_name}
PROPERTIES
OUTPUT_NAME ${name}.o
)
endfunction()

add_startup_object(
crt1
SRCS
crt1.cpp
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Nit: formatting.

Suggested change
SRCS
crt1.cpp
SRCS
crt1.cpp

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This is done

)

add_custom_target(libc-startup)
set(startup_components crt1)
foreach(target IN LISTS startup_components)
set(fq_target_name libc.startup.uefi.${target})
add_dependencies(libc-startup ${fq_target_name})
install(FILES $<TARGET_OBJECTS:${fq_target_name}>
DESTINATION ${LIBC_INSTALL_LIBRARY_DIR}
RENAME $<TARGET_PROPERTY:${fq_target_name},OUTPUT_NAME>
COMPONENT libc)
endforeach()
29 changes: 29 additions & 0 deletions libc/startup/uefi/crt1.cpp
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//===-- Implementation of crt for UEFI ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===--------------------------------------------------------------------===//
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Nit: formatting.

Suggested change
//===-- Implementation of crt for UEFI ----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===--------------------------------------------------------------------===//
//===-- Implementation of crt for UEFI ------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

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This is done


#include "include/llvm-libc-macros/stdlib-macros.h"
#include "include/llvm-libc-types/EFI_HANDLE.h"
#include "include/llvm-libc-types/EFI_STATUS.h"
#include "include/llvm-libc-types/EFI_SYSTEM_TABLE.h"
#include "src/__support/macros/config.h"

EFI_HANDLE efi_image_handle;
EFI_SYSTEM_TABLE *efi_system_table;
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We shouldn't be placing new symbols into the global namespace, that's problematic from C standard perspective, so these symbols need to prefixed with __llvm_libc_.

Suggested change
EFI_HANDLE efi_image_handle;
EFI_SYSTEM_TABLE *efi_system_table;
EFI_HANDLE __llvm_libc_efi_image_handle;
EFI_SYSTEM_TABLE *__llvm_libc_efi_system_table;

Do you know if there's a common convention for accessing these symbols? I looked at EDK2 and there it seems like these symbols are usually passed through explicitly as input arguments to functions that need them, but I don't know if there are other examples other than EDK2.

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There isn't a standard way so this was the compromise. I could join the UEFI forum IRC and inquire about it but I wouldn't be surprised if it's a "there is no standard" solution. My thinking was this would at least be an easily recognizable way programs could access the UEFI stuff if they need it for things like graphics or networking.

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Also you need extern "C" for these symbols to avoid mangling.

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I got symbol not found errors with that when I tried linking against the start file.

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I got it to build correctly with extern.


extern "C" int main(int argc, char **argv, char **envp);

extern "C" EFI_STATUS EfiMain(EFI_HANDLE ImageHandle,
EFI_SYSTEM_TABLE *SystemTable) {
efi_image_handle = ImageHandle;
efi_system_table = SystemTable;

main(0, NULL, NULL);
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Nit:

Suggested change
main(0, NULL, NULL);
main(0, nullptr, nullptr);

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This is done


// TODO: convert the return value of main to EFI_STATUS
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How involved is this? Is there a reason for not doing this right away?

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I'm not entirely sure since there's no errno numbers defined so we'll have to make them up. I didn't want to complicate things too much in this PR so this is just a MVP.

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There's C standard errno values if nothing else.

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I was going to add something to convert the error codes, where should it live in src? Under __support/OSUtil or somewhere else? I was thinking it may not be a bad idea for programs to be able to reuse the conversion.

return 0; // TODO: EFI_SUCCESS
}
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