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Userland: Respect red-zone for signal handlers

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We were building with red-zone before, but were not accounting for it on
signal handler entries. This should fix that.

Also shorten the stack alignment calculations for this.
This commit is contained in:
Hediadyoin1 2021-07-02 00:57:48 +02:00 • committed by Gunnar Beutner
parent 0fcb048448
commit d12e14fa95
Notes: sideshowbarker 2024-07-18 11:04:08 +09:00
1 changed files with 8 additions and 3 deletions
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11
Kernel/Thread.cpp
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@ -846,7 +846,9 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
// Align the stack to 16 bytes.
// Note that we push 56 bytes (4 * 14) on to the stack,
// so we need to account for this here.
FlatPtr stack_alignment = (*stack - 56) % 16;
// 56 % 16 = 8, so we only need to take 8 bytes into consideration for
// the stack alignment.
FlatPtr stack_alignment = (*stack - 8) % 16;
*stack -= stack_alignment;
push_value_on_user_stack(stack, ret_eflags);
@ -864,8 +866,11 @@ DispatchSignalResult Thread::dispatch_signal(u8 signal)
// Align the stack to 16 bytes.
// Note that we push 176 bytes (8 * 22) on to the stack,
// so we need to account for this here.
FlatPtr stack_alignment = (*stack - 112) % 16;
*stack -= stack_alignment;
// 22 % 2 = 0, so we dont need to take anything into consideration
// for the alignment.
// We also are not allowed to touch the thread's red-zone of 128 bytes
FlatPtr stack_alignment = *stack % 16;
*stack -= 128 + stack_alignment;
push_value_on_user_stack(stack, ret_rflags);