Bananymous/banan-os
1
1
Fork 1
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Kernel: If userspace sets fs or gs, dont overwrite it

Browse Source 
Current cpu index is stored at either segment. If userspace sets that
segment, kernel will not overwrite it on every reschedule. This is fine
as long as user program does not use anything that relies on it :)
This commit is contained in:
Bananymous
2026-04-04 23:35:33 +03:00
parent d7e292a9f8
commit df257755f7
3 changed files with 16 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/include/kernel/Thread.h
View File

@@ -177,7 +177,9 @@ namespace Kernel
bool m_is_userspace { false };
bool m_delete_process { false };
bool m_has_custom_fsbase { false };
vaddr_t m_fsbase { 0 };
bool m_has_custom_gsbase { false };
vaddr_t m_gsbase { 0 };
SchedulerQueue::Node* m_scheduler_node { nullptr };

8
kernel/kernel/Process.cpp
View File

@@ -3302,7 +3302,9 @@ namespace Kernel
BAN::ErrorOr<long> Process::sys_set_fsbase(void* addr)
{
Thread::current().set_fsbase(reinterpret_cast<vaddr_t>(addr));
auto& thread = Thread::current();
thread.m_has_custom_fsbase = true;
thread.set_fsbase(reinterpret_cast<vaddr_t>(addr));
Processor::load_fsbase();
return 0;
}
@@ -3314,7 +3316,9 @@ namespace Kernel
BAN::ErrorOr<long> Process::sys_set_gsbase(void* addr)
{
Thread::current().set_gsbase(reinterpret_cast<vaddr_t>(addr));
auto& thread = Thread::current();
thread.m_has_custom_gsbase = true;
thread.set_gsbase(reinterpret_cast<vaddr_t>(addr));
Processor::load_gsbase();
return 0;
}

8
kernel/kernel/Thread.cpp
View File

@@ -305,6 +305,14 @@ namespace Kernel
if (!is_userspace() || !has_process())
return;
#if ARCH(x86_64)
if (m_has_custom_gsbase)
return;
#elif ARCH(i686)
if (m_has_custom_fsbase)
return;
#endif
const vaddr_t vaddr = process().shared_page_vaddr() + Processor::current_index();
#if ARCH(x86_64)