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Kernel/LibC/DynamicLoader: Update process start ABI

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We now use SysV abi for process startup
This commit is contained in:
Bananymous
2025-04-15 23:04:20 +03:00
parent e6026cb0b8
commit 36baf7b0af
12 changed files with 314 additions and 280 deletions
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93
userspace/programs/DynamicLoader/main.cpp
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@@ -1,5 +1,6 @@
#include "utils.h"
#include <LibELF/AuxiliaryVector.h>
#include <LibELF/Types.h>
#include <LibELF/Values.h>
@@ -15,42 +16,44 @@ void _start()
{
#if defined(__x86_64__)
asm volatile(
"xorq %rbp, %rbp;"
"movq (%rsp), %rdi;"
"leaq 8(%rsp), %rsi;"
"leaq 8(%rsi, %rdi, 8), %rdx;"
"movq %rsp, %rbp;"
"andq $-16, %rsp;"
"call _entry;"
"movq %rbp, %rsp;"
"xorq %rbp, %rbp;"
"jmp *%rax;"
"ud2;"
);
#elif defined(__i686__)
asm volatile(
"xorl %ebp, %ebp;"
"pushl %ecx;"
"movl (%esp), %edi;"
"leal 4(%esp), %esi;"
"leal 4(%esi, %edi, 4), %edx;"
"movl %esp, %ebp;"
"andl $-16, %esp;"
"subl $4, %esp;"
"pushl %edx;"
"pushl %esi;"
"pushl %edi;"
"call _entry;"
"ud2;"
);
#else
#error "unsupported architecture"
#endif
}
__attribute__((naked, noreturn))
static void call_entry_point(int, char**, char**, uintptr_t)
{
#if defined(__x86_64__)
asm volatile(
"andq $-16, %rsp;"
"jmp *%rcx;"
);
#elif defined(__i686__)
asm volatile(
"addl $4, %esp;"
"popl %edi;"
"popl %esi;"
"popl %edx;"
"popl %ecx;"
"andl $-16, %esp;"
"jmp *%ecx;"
"call _entry;"
"movl %ebp, %esp;"
"xorl %ebp, %ebp;"
"jmp *%eax;"
"ud2;"
);
#else
#error "unsupported architecture"
@@ -901,16 +904,33 @@ static void call_init_funcs(LoadedElf& elf, bool is_main_elf)
reinterpret_cast<init_t>(elf.init)();
for (size_t i = 0; i < elf.init_arraysz / sizeof(init_t); i++)
reinterpret_cast<init_t*>(elf.init_array)[i]();
}
static LibELF::AuxiliaryVector* find_auxv(char** envp)
{
if (envp == nullptr)
return nullptr;
char** null_env = envp;
while (*null_env)
null_env++;
return reinterpret_cast<LibELF::AuxiliaryVector*>(null_env + 1);
}
extern "C"
__attribute__((used, noreturn))
int _entry(int argc, char** argv, char** envp, int fd)
__attribute__((used))
uintptr_t _entry(int argc, char* argv[], char* envp[])
{
const bool invoked_directly = (fd < 0);
if (invoked_directly)
int execfd = -1;
if (auto* auxv = find_auxv(envp))
for (auto* aux = auxv; aux->a_type != LibELF::AT_NULL; aux++)
if (aux->a_type == LibELF::AT_EXECFD) {
execfd = aux->a_un.a_val;
aux->a_type = LibELF::AT_IGNORE;
}
if (execfd == -1)
{
if (argc < 2)
print_error_and_exit("missing program name", 0);
@@ -918,18 +938,19 @@ int _entry(int argc, char** argv, char** envp, int fd)
argc--;
argv++;
fd = syscall(SYS_OPENAT, AT_FDCWD, argv[0], O_RDONLY);
if (fd < 0)
print_error_and_exit("could not open program", fd);
execfd = syscall(SYS_OPENAT, AT_FDCWD, argv[0], O_RDONLY);
if (execfd < 0)
print_error_and_exit("could not open program", execfd);
}
init_random();
auto& elf = load_elf(argv[0], fd);
auto& elf = load_elf(argv[0], execfd);
syscall(SYS_CLOSE, fd);
fini_random();
relocate_elf(elf, true);
initialize_environ(envp);
call_init_funcs(elf, true);
call_entry_point(argc, argv, envp, elf.base + elf.file_header.e_entry);
return elf.base + elf.file_header.e_entry;
}