//-------------------------------------------------------------------
//	segvtrap.cpp
//
//	This program shows how a signal-handler can be used to help
//	diagnose the cause of a 'Segmentation Violation' exception.
//
//		to compile:  $ g++ segvtrap.cpp -o segvtrap
//		to execute:  $ ./segvtrap
//
//	programmer: ALLAN CRUSE
//	written on: 11 MAY 2005
//	revised on: 18 MAR 2009 -- for x86_64 Linux kernel 2.6.26.6
//-------------------------------------------------------------------

#include <stdio.h>	// for printf() 
#include <stdlib.h>	// for exit() 
#include <signal.h>	// for sigaction()



// declare the function prototype for our signal-handler
void my_sigaction( int signum, siginfo_t *si, void *data );



int main( int argc, char **argv )
{
	// install our signal-handler
	static struct sigaction	sa = {0};
	sigemptyset( &sa.sa_mask );
	sa.sa_flags = SA_SIGINFO;
	sa.sa_sigaction = my_sigaction;
	sigaction( SIGSEGV, &sa, NULL );

	// setup registers with demonstration values
	asm(" movq $0xAAAAAAAAAAAAAAAA, %rax ");
	asm(" movq $0xBBBBBBBBBBBBBBBB, %rbx ");
	asm(" movq $0xCCCCCCCCCCCCCCCC, %rcx ");
	asm(" movq $0xDDDDDDDDDDDDDDDD, %rdx ");
	asm(" movq $0xEEEEEEEEEEEEEEEE, %rsi ");
	asm(" movq $0xFFFFFFFFFFFFFFFF, %rdi ");
	asm(" movq $0x8888888888888888, %r8  ");
	asm(" movq $0x9999999999999999, %r9  ");
	
	// try to execute a privileged instruction
	asm(" hlt ");	
	
	// terminate this program with status-code 0
	exit( 0 );
}







void my_sigaction( int signum, siginfo_t *si, void *data )
{
	struct sigcontext	*sc = (struct sigcontext *)((long)data+40);

	// display CPU registers
	printf( "\nsignal %d ", signum );
	printf( "EFLAGS=%016lX ", sc->eflags );
	printf( "\n" );
	printf( "RAX=%016lX ", sc->rax );
	printf( "RBX=%016lX ", sc->rbx );
	printf( "RSP=%016lX ", sc->rsp );
	//printf( "SS=%04lX ", sc->ss );
	//printf( "ES=%04lX ", sc->es );
	printf( "\n" );
	printf( "RCX=%016lX ", sc->rcx );
	printf( "RDX=%016lX ", sc->rdx );
	printf( "RIP=%016lX ", sc->rip );
	//printf( "CS=%04lX ", sc->cs );
	//printf( "FS=%04lX ", sc->fs );
	printf( "\n" );
	printf( "RSI=%016lX ", sc->rsi );
	printf( "RDI=%016lX ", sc->rdi );
	printf( "RBP=%016lX ", sc->rbp );
	//printf( "DS=%04lX ", sc->ds );
	//printf( "GS=%04lX ", sc->gs );
	printf( "\n" );

	printf( " R8=%016lX ", sc->r8 );
	printf( " R9=%016lX ", sc->r9 );
	printf( "R10=%016lX ", sc->r10 );
	printf( "\n" );

	printf( "R11=%016lX ", sc->r11 );
	printf( "R12=%016lX ", sc->r12 );
	printf( "R13=%016lX ", sc->r13 );
	printf( "\n" );

	printf( "R14=%016lX ", sc->r14 );
	printf( "R15=%016lX ", sc->r15 );
	printf( "\n" );

	// display some values from the top of the stack
	unsigned long	*lp = (unsigned long *)sc->rsp;
	printf( "\n[SS:ESP]  " );
	for (int i = 0; i < 4; i++) printf( "%016X ", lp[i] );

	// display some bytes from the instruction-stream
	unsigned char	*ip = (unsigned char *)sc->rip;
	printf( "\n[CS:RIP]  " );
	for (int i = 0; i < 15; i++) printf( "%02X ", ip[i] );
	printf( "\n\n" );
	// terminate this program with status-code 1
	exit( 1 );
}