rework signal handling

JIRA: RTOS-539

arch/armv7a/signal.S

@@ -20,15 +20,13 @@
 .globl _signal_trampoline
 .type _signal_trampoline, %function
 _signal_trampoline:
-	// stack: return address, signal number
-	push {r0-r3,r9,r12,lr}
-	mrs r0, apsr
-	push {r0}
-	ldr r0, [sp, #32]
-	blx _signal_handler
+	/* Get signal number from stack */
 	pop {r0}
-	msr apsr_nzcvqg, r0
-	pop {r0-r3,r9,r12,lr}
-	add sp, #4
-	pop {pc}
+	blx _signal_handler
+
+	/* Old signal mask in r0 */
+	pop {r1} /* cpu context * */
+	pop {r2} /* pc */
+	pop {r3} /* sp */
+	bl sigreturn
 .size _signal_trampoline, .-_signal_trampoline

arch/ia32/signal.S

@@ -20,22 +20,13 @@
 .globl _signal_trampoline
 .type _signal_trampoline, %function
 _signal_trampoline:
-	// stack: return address, signal number
-	xchgl (%esp), %eax
-	push %ebx
-	push %ecx
-	push %edx
-	pushf
-
-	push %eax
+	/* Signal number on stack */
 	call _signal_handler
-	addl $4, %esp
 
-	popf
-	pop %edx
-	pop %ecx
-	pop %ebx
-	pop %eax
-	ret
+	addl $4, %esp
+	/* Put old mask on stack */
+	push %eax
+	/* cpu context *, eip, esp on stack */
+	call sigreturn
 .size _signal_trampoline, .-_signal_trampoline
 

arch/riscv64/signal.S

@@ -20,51 +20,14 @@
 .globl _signal_trampoline
 .type _signal_trampoline, %function
 _signal_trampoline:
-
-	// stack: return address, signal number
-	addi sp, sp, -136
-	sd x1, (sp)          /* ra */
-	sd x3, 8(sp)         /* gp */
-	sd x5, 16(sp)        /* t0 */
-	sd x6, 24(sp)        /* t1 */
-	sd x7, 32(sp)        /* t2 */
-	sd x10, 40(sp)       /* a0 */
-	sd x11, 48(sp)       /* a1 */
-	sd x12, 56(sp)       /* a2 */
-	sd x13, 64(sp)       /* a3 */
-	sd x14, 72(sp)       /* a4 */
-	sd x15, 80(sp)       /* a5 */
-	sd x16, 88(sp)       /* a6 */
-	sd x17, 96(sp)       /* a7 */
-	sd x28, 104(sp)      /* t3 */
-	sd x29, 112(sp)      /* t4 */
-	sd x30, 120(sp)      /* t5 */
-	sd x31, 128(sp)      /* t6 */
-
-	ld a0, 136(sp)      /* signal number is 1st argument */
+	/* Get signal number from stack */
+	lw a0, (sp)
 	call _signal_handler
 
-	ld x1, (sp)          /* ra */
-	ld x3, 8(sp)         /* gp */
-	ld x5, 16(sp)        /* t0 */
-	ld x6, 24(sp)        /* t1 */
-	ld x7, 32(sp)        /* t2 */
-	ld x10, 40(sp)       /* a0 */
-	ld x11, 48(sp)       /* a1 */
-	ld x12, 56(sp)       /* a2 */
-	ld x13, 64(sp)       /* a3 */
-	ld x14, 72(sp)       /* a4 */
-	ld x15, 80(sp)       /* a5 */
-	ld x16, 88(sp)       /* a6 */
-	ld x17, 96(sp)       /* a7 */
-	ld x28, 104(sp)      /* t3 */
-	ld x29, 112(sp)      /* t4 */
-	ld x30, 120(sp)      /* t5 */
-	ld x31, 128(sp)      /* t6 */
-	addi sp, sp, 144     /* saved state, signal number and return address on stack */
-
-	/* TODO correct this, it is wrong, we need a way to load pc without touching any other register */
-	ld t4, -8(sp)
-	jr t4
-
+	/* Old signal mask in a0 */
+	ld a1, 8(sp)  /* cpu context * */
+	ld a2, 16(sp) /* sepc */
+	ld a3, 24(sp) /* sp */
+	addi sp, sp, 32
+	call sigreturn
 .size _signal_trampoline, .-_signal_trampoline

signal/signal.c

@@ -123,14 +123,14 @@ static int _signal_ismutable(int sig)
 }
 
 
-void _signal_handler(int phxsig)
+unsigned int _signal_handler(int phxsig)
 {
 	int sig;
 	unsigned int oldmask;
 
 	if (phxsig < 0 || phxsig >= NSIG) {
 		/* Don't know what to do, ignore it */
-		return;
+		return signalMask(0U, 0U);
 	}
 
 	/* Received Phoenix signal, need to convert it to POSIX signal */
@@ -141,7 +141,9 @@ void _signal_handler(int phxsig)
 	/* Invoke handler */
 	(signal_common.sightab[sig])(sig);
 
-	signalMask(oldmask, 0xffffffffUL);
+	/* Mask restored by sigreturn */
+
+	return oldmask;
 }