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Kernel: Make processes start with a 16-byte-aligned stack

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Sahan Fernando 2021-05-02 03:22:00 +10:00 • committed by Andreas Kling
parent cf7df418ed
commit bd563f0b3c
1 changed files with 6 additions and 0 deletions
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6
Kernel/Syscalls/execve.cpp
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@ -131,12 +131,18 @@ static KResultOr<FlatPtr> make_userspace_stack_for_main_thread(Region& region, V
// NOTE: The stack needs to be 16-byte aligned.
new_esp -= new_esp % 16;
// GCC assumes that the return address has been pushed to the stack when it enters the function,
// so we need to reserve an extra pointer's worth of bytes below this to make GCC's stack alignment
// calculations work
new_esp -= sizeof(void*);
push_on_new_stack((FlatPtr)envp);
push_on_new_stack((FlatPtr)argv);
push_on_new_stack((FlatPtr)argv_entries.size());
push_on_new_stack(0);
VERIFY((new_esp + sizeof(void*)) % 16 == 0);
return new_esp;
}