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Kernel: Share the "return to ring 0/3 from signal" trampolines globally.

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Generate a special page containing the "return from signal" trampoline code
on startup and then route signalled threads to it. This avoids a page
allocation in every process that ever receives a signal.
This commit is contained in:
Andreas Kling
2019-07-19 17:01:16 +02:00
parent fdf931cfce
commit f8beb0f665
5 changed files with 36 additions and 21 deletions
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5
Kernel/Thread.cpp
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@@ -362,7 +362,6 @@ ShouldUnblockThread Thread::dispatch_signal(u8 signal)
bool interrupting_in_kernel = (ret_cs & 3) == 0;
ProcessPagingScope paging_scope(m_process);
m_process.create_signal_trampolines_if_needed();
if (interrupting_in_kernel) {
#ifdef SIGNAL_DEBUG
@@ -419,9 +418,9 @@ ShouldUnblockThread Thread::dispatch_signal(u8 signal)
push_value_on_stack(signal);
if (interrupting_in_kernel)
push_value_on_stack(m_process.m_return_to_ring0_from_signal_trampoline.get());
push_value_on_stack(g_return_to_ring0_from_signal_trampoline.get());
else
push_value_on_stack(m_process.m_return_to_ring3_from_signal_trampoline.get());
push_value_on_stack(g_return_to_ring3_from_signal_trampoline.get());
ASSERT((m_tss.esp % 16) == 0);