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Kernel: Simplify PageDirectory swapping in sys$execve()

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Swap out both the PageDirectory and the Region list at the same time,
instead of doing the Region list slightly later.
This commit is contained in:
Andreas Kling 2020-01-19 16:05:42 +01:00
parent d394267f50
commit 1dc9fa9506
1 changed files with 2 additions and 10 deletions
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12
Kernel/Process.cpp
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@ -727,9 +727,8 @@ int Process::do_exec(NonnullRefPtr<FileDescription> main_program_description, Ve
return -ETXTBSY; return -ETXTBSY;
} }
u32 entry_eip = 0;
// FIXME: Is there a race here?
auto old_page_directory = move(m_page_directory); auto old_page_directory = move(m_page_directory);
auto old_regions = move(m_regions);
m_page_directory = PageDirectory::create_for_userspace(*this); m_page_directory = PageDirectory::create_for_userspace(*this);
#ifdef MM_DEBUG #ifdef MM_DEBUG
dbgprintf("Process %u exec: PD=%x created\n", pid(), m_page_directory.ptr()); dbgprintf("Process %u exec: PD=%x created\n", pid(), m_page_directory.ptr());
@ -761,20 +760,13 @@ int Process::do_exec(NonnullRefPtr<FileDescription> main_program_description, Ve
ASSERT(region); ASSERT(region);
// NOTE: We yank this out of 'm_regions' since we're about to manipulate the vector
// and we don't want it getting lost.
auto executable_region = m_regions.take_last();
Region* master_tls_region { nullptr }; Region* master_tls_region { nullptr };
size_t master_tls_size = 0; size_t master_tls_size = 0;
size_t master_tls_alignment = 0; size_t master_tls_alignment = 0;
u32 entry_eip = 0;
OwnPtr<ELFLoader> loader; OwnPtr<ELFLoader> loader;
{ {
// Okay, here comes the sleight of hand, pay close attention..
auto old_regions = move(m_regions);
m_regions.append(move(executable_region));
ArmedScopeGuard rollback_regions_guard([&]() { ArmedScopeGuard rollback_regions_guard([&]() {
ASSERT(&current->process() == this); ASSERT(&current->process() == this);
m_page_directory = move(old_page_directory); m_page_directory = move(old_page_directory);