kernel/arm: implement signals, fork, restart syscall

Change-Id: I24219b83d90710ef719190183ba6f069f82dae61
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6198
Tested-by: Automation <automation@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

headers/posix/arch/arm/signal.h

@@ -30,7 +30,9 @@ struct vregs
 	ulong r14;	/* link register */
 	ulong r15;	/* program counter */
 	ulong cpsr;
-// TODO: ARM: fix floats in vregs, add missing stuff.
+
+	double d[32];
+	ulong fpscr;
 };
 #endif /* defined(__arm__) */
 

headers/private/kernel/arch/arm/arch_cpu.h

@@ -24,30 +24,6 @@
 #include <arch/arm/arch_thread_types.h>
 #include <kernel.h>
 
-
-/* raw exception frames */
-struct iframe {
-	uint32 spsr;
-	uint32 r0;
-	uint32 r1;
-	uint32 r2;
-	uint32 r3;
-	uint32 r4;
-	uint32 r5;
-	uint32 r6;
-	uint32 r7;
-	uint32 r8;
-	uint32 r9;
-	uint32 r10;
-	uint32 r11;
-	uint32 r12;
-	uint32 usr_sp;
-	uint32 usr_lr;
-	uint32 svc_sp;
-	uint32 svc_lr;
-	uint32 pc;
-} _PACKED;
-
 /**! Values for arch_cpu_info.arch */
 enum {
 	ARCH_ARM_PRE_ARM7,

headers/private/kernel/arch/arm/arch_thread_types.h

@@ -7,6 +7,30 @@
 
 #include <kernel.h>
 
+
+/* raw exception frames */
+struct iframe {
+	uint32 spsr;
+	uint32 r0;
+	uint32 r1;
+	uint32 r2;
+	uint32 r3;
+	uint32 r4;
+	uint32 r5;
+	uint32 r6;
+	uint32 r7;
+	uint32 r8;
+	uint32 r9;
+	uint32 r10;
+	uint32 r11;
+	uint32 r12;
+	uint32 usr_sp;
+	uint32 usr_lr;
+	uint32 svc_sp;
+	uint32 svc_lr;
+	uint32 pc;
+} _PACKED;
+
 #define	IFRAME_TRACE_DEPTH 4
 
 struct iframe_stack {
@@ -26,6 +50,9 @@ struct arch_thread {
 
 	// used to track interrupts on this thread
 	struct iframe_stack	iframes;
+
+	struct iframe*	userFrame;
+	uint32	oldR0;
 };
 
 struct arch_team {
@@ -36,10 +63,7 @@ struct arch_team {
 };
 
 struct arch_fork_arg {
-	// gcc treats empty structures as zero-length in C, but as if they contain
+	struct iframe	frame;
-	// a char in C++. So we have to put a dummy in to be able to use the struct
-	// from both in a consistent way.
-	char	dummy;
 };
 
 

headers/private/system/arch/arm/arch_commpage_defs.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, Haiku Inc. All rights reserved.
+ * Copyright 2022-2023, Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Copyright 2007, Travis Geiselbrecht. All rights reserved.
@@ -12,6 +12,7 @@
 #	error Must not be included directly. Include <commpage_defs.h> instead!
 #endif
 
-#define COMMPAGE_ENTRY_ARM_THREAD_EXIT	(COMMPAGE_ENTRY_FIRST_ARCH_SPECIFIC + 0)
+#define COMMPAGE_ENTRY_ARM_SIGNAL_HANDLER	(COMMPAGE_ENTRY_FIRST_ARCH_SPECIFIC + 0)
+#define COMMPAGE_ENTRY_ARM_THREAD_EXIT		(COMMPAGE_ENTRY_FIRST_ARCH_SPECIFIC + 1)
 
 #endif	/* _SYSTEM_ARCH_ARM_COMMPAGE_DEFS_H */

src/system/kernel/arch/arm/Jamfile

@@ -67,5 +67,5 @@ KernelMergeObject kernel_arch_arm.o :
 CreateAsmStructOffsetsHeader asm_offsets.h : asm_offsets.cpp : $(TARGET_KERNEL_ARCH) ;
 
 # syscall headers are generated on the fly, so we need a explicit dependency.
-Includes [ FGristFiles arch_int.cpp arch_asm.S ]
+Includes [ FGristFiles arch_commpage.cpp arch_int.cpp arch_asm.S ]
 	: <syscalls!$(TARGET_PACKAGING_ARCH)>syscall_numbers.h ;

src/system/kernel/arch/arm/arch_commpage.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022, Haiku Inc. All rights reserved.
+ * Copyright 2022-2023, Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Copyright 2009, Johannes Wischert, johanneswi@gmail.com.
@@ -17,10 +17,34 @@
 #include <elf.h>
 #include <smp.h>
 
+#include "syscall_numbers.h"
+
 
 extern "C" void arch_user_thread_exit();
 
 
+extern "C" void __attribute__((noreturn))
+arch_user_signal_handler(signal_frame_data* data)
+{
+	if (data->siginfo_handler) {
+		auto handler = (void (*)(int, siginfo_t*, void*, void*))data->handler;
+		handler(data->info.si_signo, &data->info, &data->context, data->user_data);
+	} else {
+		auto handler = (void (*)(int, void*, vregs*))data->handler;
+		handler(data->info.si_signo, data->user_data, &data->context.uc_mcontext);
+	}
+
+	// _kern_restore_signal_frame(data)
+	asm volatile(
+		"mov r0, %[data];"
+		"svc %[syscall_num]"
+		:: [data] "r"(data), [syscall_num] "i" (SYSCALL_RESTORE_SIGNAL_FRAME)
+	);
+
+	__builtin_unreachable();
+}
+
+
 static void
 register_commpage_function(const char* functionName, int32 commpageIndex,
 	const char* commpageSymbolName, addr_t expectedAddress)
@@ -55,10 +79,13 @@ arch_commpage_init(void)
 status_t
 arch_commpage_init_post_cpus(void)
 {
+	register_commpage_function("arch_user_signal_handler",
+		COMMPAGE_ENTRY_ARM_SIGNAL_HANDLER, "commpage_signal_handler",
+		(addr_t)&arch_user_signal_handler);
+
 	register_commpage_function("arch_user_thread_exit",
 		COMMPAGE_ENTRY_ARM_THREAD_EXIT, "commpage_thread_exit",
 		(addr_t)&arch_user_thread_exit);
 
 	return B_OK;
 }
-

src/system/kernel/arch/arm/arch_int.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2022, Haiku Inc. All rights reserved.
+ * Copyright 2003-2023, Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -276,6 +276,10 @@ arch_arm_syscall(struct iframe *iframe)
 		}
 	}
 
+	thread_get_current_thread()->arch_info.userFrame = iframe;
+	thread_get_current_thread()->arch_info.oldR0 = iframe->r0;
+	thread_at_kernel_entry(system_time());
+
 	enable_interrupts();
 
 	uint64 returnValue = 0;
@@ -283,6 +287,24 @@ arch_arm_syscall(struct iframe *iframe)
 
 	TRACE("returning %" B_PRId64 "\n", returnValue);
 	iframe->r0 = returnValue;
+
+	disable_interrupts();
+	atomic_and(&thread_get_current_thread()->flags, ~THREAD_FLAGS_SYSCALL_RESTARTED);
+	if ((thread_get_current_thread()->flags & (THREAD_FLAGS_SIGNALS_PENDING
+			| THREAD_FLAGS_DEBUG_THREAD | THREAD_FLAGS_TRAP_FOR_CORE_DUMP)) != 0) {
+		enable_interrupts();
+		thread_at_kernel_exit();
+	} else {
+		thread_at_kernel_exit_no_signals();
+	}
+	if ((thread_get_current_thread()->flags & THREAD_FLAGS_RESTART_SYSCALL) != 0) {
+		atomic_and(&thread_get_current_thread()->flags, ~THREAD_FLAGS_RESTART_SYSCALL);
+		atomic_or(&thread_get_current_thread()->flags, THREAD_FLAGS_SYSCALL_RESTARTED);
+		iframe->r0 = thread_get_current_thread()->arch_info.oldR0;
+		iframe->pc -= 4;
+	}
+
+	thread_get_current_thread()->arch_info.userFrame = NULL;
 }
 
 

src/system/kernel/arch/arm/arch_thread.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2022, Haiku Inc. All rights reserved.
+ * Copyright 2003-2023, Haiku Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  *
  * Authors:
@@ -234,7 +234,31 @@ arch_thread_enter_userspace(Thread *thread, addr_t entry,
 bool
 arch_on_signal_stack(Thread *thread)
 {
-	return false;
+	struct iframe* frame = thread->arch_info.userFrame;
+	if (frame == NULL) {
+		panic("arch_on_signal_stack(): No user iframe!");
+		return false;
+	}
+
+	return frame->usr_sp >= thread->signal_stack_base
+		&& frame->usr_sp < thread->signal_stack_base
+			+ thread->signal_stack_size;
+}
+
+
+static uint8*
+get_signal_stack(Thread* thread, struct iframe* frame,
+	struct sigaction* action, size_t spaceNeeded)
+{
+	// use the alternate signal stack if we should and can
+	if (thread->signal_stack_enabled && (action->sa_flags & SA_ONSTACK) != 0
+			&& (frame->usr_sp < thread->signal_stack_base
+			|| frame->usr_sp >= thread->signal_stack_base + thread->signal_stack_size)) {
+		addr_t stackTop = thread->signal_stack_base + thread->signal_stack_size;
+		return (uint8*)ROUNDDOWN(stackTop - spaceNeeded, 16);
+	}
+
+	return (uint8*)ROUNDDOWN(frame->usr_sp - spaceNeeded, 16);
 }
 
 
@@ -242,14 +266,99 @@ status_t
 arch_setup_signal_frame(Thread *thread, struct sigaction *sa,
 	struct signal_frame_data *signalFrameData)
 {
-	return B_ERROR;
+	iframe* frame = thread->arch_info.userFrame;
+	if (frame == NULL) {
+		panic("arch_setup_signal_frame(): No user iframe!");
+		return B_ERROR;
+	}
+
+	// store the register state in signalFrameData->context.uc_mcontext
+	signalFrameData->context.uc_mcontext.r0   = frame->r0;
+	signalFrameData->context.uc_mcontext.r1   = frame->r1;
+	signalFrameData->context.uc_mcontext.r2   = frame->r2;
+	signalFrameData->context.uc_mcontext.r3   = frame->r3;
+	signalFrameData->context.uc_mcontext.r4   = frame->r4;
+	signalFrameData->context.uc_mcontext.r5   = frame->r5;
+	signalFrameData->context.uc_mcontext.r6   = frame->r6;
+	signalFrameData->context.uc_mcontext.r7   = frame->r7;
+	signalFrameData->context.uc_mcontext.r8   = frame->r8;
+	signalFrameData->context.uc_mcontext.r9   = frame->r9;
+	signalFrameData->context.uc_mcontext.r10  = frame->r10;
+	signalFrameData->context.uc_mcontext.r11  = frame->r11;
+	signalFrameData->context.uc_mcontext.r12  = frame->r12;
+	signalFrameData->context.uc_mcontext.r13  = frame->usr_sp;
+	signalFrameData->context.uc_mcontext.r14  = frame->usr_lr;
+	signalFrameData->context.uc_mcontext.r15  = frame->pc;
+	signalFrameData->context.uc_mcontext.cpsr = frame->spsr;
+
+	arm_save_fpu((arch_fpu_context*)&signalFrameData->context.uc_mcontext.d[0]);
+
+	// Fill in signalFrameData->context.uc_stack
+	signal_get_user_stack(frame->usr_sp, &signalFrameData->context.uc_stack);
+
+	// store oldR0 in syscall_restart_return_value
+	signalFrameData->syscall_restart_return_value = thread->arch_info.oldR0;
+
+	// get the stack to use -- that's either the current one or a special signal stack
+	uint8* userStack = get_signal_stack(thread, frame, sa,
+		sizeof(*signalFrameData));
+
+	// copy the signal frame data onto the stack
+	status_t res = user_memcpy(userStack, signalFrameData,
+		sizeof(*signalFrameData));
+	if (res < B_OK)
+		return res;
+
+	// prepare the user stack frame for a function call to the signal handler wrapper function
+	addr_t commpageAddr = (addr_t)thread->team->commpage_address;
+	addr_t signalHandlerAddr;
+	ASSERT(user_memcpy(&signalHandlerAddr,
+		&((addr_t*)commpageAddr)[COMMPAGE_ENTRY_ARM_SIGNAL_HANDLER],
+		sizeof(signalHandlerAddr)) >= B_OK);
+	signalHandlerAddr += commpageAddr;
+
+	frame->usr_lr = frame->pc;
+	frame->usr_sp = (addr_t)userStack;
+	frame->pc = signalHandlerAddr;
+	frame->r0 = frame->usr_sp;
+
+	return B_OK;
 }
 
 
 int64
 arch_restore_signal_frame(struct signal_frame_data* signalFrameData)
 {
-	return 0;
+	iframe* frame = thread_get_current_thread()->arch_info.userFrame;
+	if (frame == NULL) {
+		panic("arch_restore_signal_frame(): No user iframe!");
+		return 0;
+	}
+
+	thread_get_current_thread()->arch_info.oldR0
+		= signalFrameData->syscall_restart_return_value;
+
+	frame->r0     = signalFrameData->context.uc_mcontext.r0;
+	frame->r1     = signalFrameData->context.uc_mcontext.r1;
+	frame->r2     = signalFrameData->context.uc_mcontext.r2;
+	frame->r3     = signalFrameData->context.uc_mcontext.r3;
+	frame->r4     = signalFrameData->context.uc_mcontext.r4;
+	frame->r5     = signalFrameData->context.uc_mcontext.r5;
+	frame->r6     = signalFrameData->context.uc_mcontext.r6;
+	frame->r7     = signalFrameData->context.uc_mcontext.r7;
+	frame->r8     = signalFrameData->context.uc_mcontext.r8;
+	frame->r9     = signalFrameData->context.uc_mcontext.r9;
+	frame->r10    = signalFrameData->context.uc_mcontext.r10;
+	frame->r11    = signalFrameData->context.uc_mcontext.r11;
+	frame->r12    = signalFrameData->context.uc_mcontext.r12;
+	frame->usr_sp = signalFrameData->context.uc_mcontext.r13;
+	frame->usr_lr = signalFrameData->context.uc_mcontext.r14;
+	frame->pc     = signalFrameData->context.uc_mcontext.r15;
+	frame->spsr   = signalFrameData->context.uc_mcontext.cpsr;
+
+	arm_restore_fpu((arch_fpu_context*)&signalFrameData->context.uc_mcontext.d[0]);
+
+	return frame->r0;
 }
 
 
@@ -266,6 +375,13 @@ arch_check_syscall_restart(Thread *thread)
 void
 arch_store_fork_frame(struct arch_fork_arg *arg)
 {
+	struct iframe* frame = thread_get_current_thread()->arch_info.userFrame;
+	if (frame == NULL) {
+		panic("arch_store_fork_frame(): No user iframe!");
+	}
+
+	arg->frame = *frame;
+	arg->frame.r0 = 0; // fork return value
 }
 
 
@@ -279,4 +395,6 @@ arch_store_fork_frame(struct arch_fork_arg *arg)
 void
 arch_restore_fork_frame(struct arch_fork_arg *arg)
 {
+	disable_interrupts();
+	arch_return_to_userland(&arg->frame);
 }