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Kernel: Implement signal trampoline for aarch64

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With this change, we are now able to successfully boot into the text
mode! :^)
This commit is contained in:
Timon Kruiper 2023-04-01 15:30:11 +02:00 committed by Idan Horowitz
parent ec765544a5
commit 4e00c63897
Notes: sideshowbarker 2024-07-17 02:05:41 +09:00 
Author: https://github.com/FireFox317
Commit: https://github.com/SerenityOS/serenity/commit/4e00c63897
Pull-request: https://github.com/SerenityOS/serenity/pull/18149
Reviewed-by: https://github.com/IdanHo ✅
1 changed files with 26 additions and 3 deletions
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29
Kernel/Process.cpp
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@ -1,5 +1,6 @@
/*
* Copyright (c) 2018-2023, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2023, Timon Kruiper <timonkruiper@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -411,14 +412,36 @@ void signal_trampoline_dummy()
: "i"(Syscall::SC_sigreturn),
"i"(offset_to_first_register_slot));
#elif ARCH(AARCH64)
constexpr static auto offset_to_first_register_slot = align_up_to(sizeof(__ucontext) + sizeof(siginfo) + sizeof(FPUState) + 3 * sizeof(FlatPtr), 16);
asm(
".global asm_signal_trampoline\n"
"asm_signal_trampoline:\n"
// TODO: Implement this when we support userspace for aarch64
"wfi\n"
// stack state: 0, ucontext, signal_info (alignment = 16), fpu_state (alignment = 16), ucontext*, siginfo*, signal, handler
// Load the handler address into x3.
"ldr x3, [sp, #0]\n"
// Store x0 (return value from a syscall) into the register slot, such that we can return the correct value in sys$sigreturn.
"str x0, [sp, %[offset_to_first_register_slot]]\n"
// Load the signal number into the first argument.
"ldr x0, [sp, #8]\n"
// Load a pointer to the signal_info structure into the second argument.
"ldr x1, [sp, #16]\n"
// Load a pointer to the ucontext into the third argument.
"ldr x2, [sp, #24]\n"
// Pop the values off the stack.
"add sp, sp, 32\n"
// Call the signal handler.
"blr x3\n"
// Call sys$sigreturn.
"mov x8, %[sigreturn_syscall_number]\n"
"svc #0\n"
// We should never return, so trap if we do return.
"brk #0\n"
"\n"
".global asm_signal_trampoline_end\n"
"asm_signal_trampoline_end: \n");
"asm_signal_trampoline_end: \n" ::[sigreturn_syscall_number] "i"(Syscall::SC_sigreturn),
[offset_to_first_register_slot] "i"(offset_to_first_register_slot));
#else
# error Unknown architecture
#endif