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Kernel: Disable big process lock for sys$get_stack_bounds

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This syscall only reads from the shared m_space field, but that field
is only over written to by Process::attach_resources, before the
process was initialized (aka, before syscalls can happen), by
Process::finalize which is only called after all the process' threads
have exited (aka, syscalls can not happen anymore), and by
Process::do_exec which calls all other syscall-capable threads before
doing so. Space's find_region_containing already holds its own lock,
and as such there's no need to hold the big lock.
This commit is contained in:
Idan Horowitz 2021-08-06 15:21:08 +03:00 committed by Andreas Kling
parent d40038a04f
commit efeb01e35f
Notes: sideshowbarker 2024-07-18 07:23:26 +09:00 
Author: https://github.com/IdanHo
Commit: https://github.com/SerenityOS/serenity/commit/efeb01e35fc
Pull-request: https://github.com/SerenityOS/serenity/pull/9236
Reviewed-by: https://github.com/tomuta ✅
2 changed files with 2 additions and 2 deletions
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2
Kernel/API/Syscall.h
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@ -177,7 +177,7 @@ enum class NeedsBigProcessLock {
S(unveil, NeedsBigProcessLock::Yes) \ S(unveil, NeedsBigProcessLock::Yes) \
S(perf_event, NeedsBigProcessLock::Yes) \ S(perf_event, NeedsBigProcessLock::Yes) \
S(shutdown, NeedsBigProcessLock::Yes) \ S(shutdown, NeedsBigProcessLock::Yes) \
S(get_stack_bounds, NeedsBigProcessLock::Yes) \ S(get_stack_bounds, NeedsBigProcessLock::No) \
S(ptrace, NeedsBigProcessLock::Yes) \ S(ptrace, NeedsBigProcessLock::Yes) \
S(sendfd, NeedsBigProcessLock::Yes) \ S(sendfd, NeedsBigProcessLock::Yes) \
S(recvfd, NeedsBigProcessLock::Yes) \ S(recvfd, NeedsBigProcessLock::Yes) \

2
Kernel/Syscalls/get_stack_bounds.cpp
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@ -11,7 +11,7 @@ namespace Kernel {
KResultOr<FlatPtr> Process::sys$get_stack_bounds(Userspace<FlatPtr*> user_stack_base, Userspace<size_t*> user_stack_size) KResultOr<FlatPtr> Process::sys$get_stack_bounds(Userspace<FlatPtr*> user_stack_base, Userspace<size_t*> user_stack_size)
{ {
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this); VERIFY_NO_PROCESS_BIG_LOCK(this);
auto& regs = Thread::current()->get_register_dump_from_stack(); auto& regs = Thread::current()->get_register_dump_from_stack();
FlatPtr stack_pointer = regs.userspace_sp(); FlatPtr stack_pointer = regs.userspace_sp();
auto* stack_region = address_space().find_region_containing(Memory::VirtualRange { VirtualAddress(stack_pointer), 1 }); auto* stack_region = address_space().find_region_containing(Memory::VirtualRange { VirtualAddress(stack_pointer), 1 });