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Kernel: Load ELF executable pages lazily when possible.

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This currently only works for "normal" processes created by fork().
It does not work for create_user_process() processes spawned by the
kernel, as those are a bit special during construction.
This commit is contained in:
Andreas Kling 2019-03-27 04:01:15 +01:00
parent baab9f4402
commit 75207ddffd
1 changed files with 8 additions and 14 deletions
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22
Kernel/Process.cpp
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@ -322,13 +322,15 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
#endif
RetainPtr<Region> region = allocate_region_with_vmo(LinearAddress(), descriptor->metadata().size, vmo.copy_ref(), 0, "executable", true, false);
// FIXME: Should we consider doing on-demand paging here? Is it actually useful?
bool success = region->page_in();
ASSERT(success);
if (this != &current->process()) {
// FIXME: Don't force-load the entire executable at once, let the on-demand pager take care of it.
bool success = region->page_in();
ASSERT(success);
}
{
// Okay, here comes the sleight of hand, pay close attention..
auto old_regions = move(m_regions);
m_regions.append(*region);
ELFLoader loader(region->laddr().as_ptr());
loader.map_section_hook = [&] (LinearAddress laddr, size_t size, size_t alignment, size_t offset_in_image, bool is_readable, bool is_writable, const String& name) {
ASSERT(size);
@ -347,25 +349,17 @@ int Process::do_exec(String path, Vector<String> arguments, Vector<String> envir
return laddr.as_ptr();
};
bool success = loader.load();
if (!success) {
if (!success || !loader.entry().get()) {
m_page_directory = move(old_page_directory);
// FIXME: RAII this somehow instead.
ASSERT(&current->process() == this);
MM.enter_process_paging_scope(*this);
m_regions = move(old_regions);
kprintf("sys$execve: Failure loading %s\n", path.characters());
kprintf("do_exec: Failure loading %s\n", path.characters());
return -ENOEXEC;
}
entry_eip = loader.entry().get();
if (!entry_eip) {
m_page_directory = move(old_page_directory);
// FIXME: RAII this somehow instead.
ASSERT(&current->process() == this);
MM.enter_process_paging_scope(*this);
m_regions = move(old_regions);
return -ENOEXEC;
}
}
kfree(current->m_kernel_stack_for_signal_handler);