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Kernel: Add support for SA_SIGINFO

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We currently don't really populate most of the fields, but that can
wait :^)
This commit is contained in:
Ali Mohammad Pur 2022-02-26 00:58:06 +03:30 • committed by Andreas Kling
parent 585054d68b
commit 4bd01b7fe9
12 changed files with 408 additions and 195 deletions
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60
Kernel/Process.cpp
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@ -293,63 +293,69 @@ void signal_trampoline_dummy()
// blocking syscall, that syscall may return some special error code in eax;
// This error code would likely be overwritten by the signal handler, so it's
// necessary to preserve it here.
constexpr static auto offset_to_first_register_slot = sizeof(__ucontext) + sizeof(siginfo) + 5 * sizeof(FlatPtr);
asm(
".intel_syntax noprefix\n"
".globl asm_signal_trampoline\n"
"asm_signal_trampoline:\n"
// stack state: ret flags, ret ip, register dump, signal mask, signal, handler (alignment = 16), 0
// stack state: 0, ucontext, signal_info, (alignment = 16), 0, ucontext*, siginfo*, signal, (alignment = 16), handler
// save ebp
"push ebp\n"
"mov ebp, esp\n"
// Pop the handler into ecx
"pop ecx\n" // save handler
// we have to save eax 'cause it might be the return value from a syscall
"push eax\n"
// align the stack to 16 bytes (as our current offset is 12 from the fake return addr, saved ebp and saved eax)
"sub esp, 4\n"
// push the signal code
"mov eax, [ebp+12]\n"
"push eax\n"
"mov [esp+%P1], eax\n"
// Note that the stack is currently aligned to 16 bytes as we popped the extra entries above.
// and it's already setup to call the handler with the expected values on the stack.
// call the signal handler
"call [ebp+8]\n"
// Unroll stack back to the saved eax
"add esp, 8\n"
"call ecx\n"
// drop the 4 arguments
"add esp, 16\n"
// Current stack state is just saved_eax, ucontext, signal_info.
// syscall SC_sigreturn
"mov eax, %P0\n"
"int 0x82\n"
".globl asm_signal_trampoline_end\n"
"asm_signal_trampoline_end:\n"
".att_syntax" ::"i"(Syscall::SC_sigreturn));
".att_syntax"
:
: "i"(Syscall::SC_sigreturn),
"i"(offset_to_first_register_slot));
#elif ARCH(X86_64)
// The trampoline preserves the current rax, pushes the signal code and
// then calls the signal handler. We do this because, when interrupting a
// blocking syscall, that syscall may return some special error code in eax;
// This error code would likely be overwritten by the signal handler, so it's
// necessary to preserve it here.
constexpr static auto offset_to_first_register_slot = sizeof(__ucontext) + sizeof(siginfo) + 4 * sizeof(FlatPtr);
asm(
".intel_syntax noprefix\n"
".globl asm_signal_trampoline\n"
"asm_signal_trampoline:\n"
// stack state: ret flags, ret ip, register dump, signal mask, signal, handler (alignment = 16), 0
// stack state: 0, ucontext, signal_info (alignment = 16), ucontext*, siginfo*, signal, handler
// save rbp
"push rbp\n"
"mov rbp, rsp\n"
// Pop the handler into rcx
"pop rcx\n" // save handler
// we have to save rax 'cause it might be the return value from a syscall
"push rax\n"
// align the stack to 16 bytes (our offset is 24 bytes from the fake return addr, saved rbp and saved rax).
"sub rsp, 8\n"
// push the signal code
"mov rdi, [rbp+24]\n"
"mov [rsp+%P1], rax\n"
// pop signal number into rdi (first param)
"pop rdi\n"
// pop siginfo* into rsi (second param)
"pop rsi\n"
// pop ucontext* into rdx (third param)
"pop rdx\n"
// Note that the stack is currently aligned to 16 bytes as we popped the extra entries above.
// call the signal handler
"call [rbp+16]\n"
// unroll stack back to the saved rax
"add rsp, 8\n"
"call rcx\n"
// Current stack state is just saved_rax, ucontext, signal_info.
// syscall SC_sigreturn
"mov rax, %P0\n"
"int 0x82\n"
".globl asm_signal_trampoline_end\n"
"asm_signal_trampoline_end:\n"
".att_syntax" ::"i"(Syscall::SC_sigreturn));
".att_syntax"
:
: "i"(Syscall::SC_sigreturn),
"i"(offset_to_first_register_slot));
#endif
}