252 lines
6.3 KiB
C
252 lines
6.3 KiB
C
/*
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* Copyright (C) 2008 Stefan Hajnoczi <stefanha@gmail.com>.
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* Copyright (C) 2016 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*
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* You can also choose to distribute this program under the terms of
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* the Unmodified Binary Distribution Licence (as given in the file
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* COPYING.UBDL), provided that you have satisfied its requirements.
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*/
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FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
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#include <stddef.h>
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#include <stdio.h>
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#include <errno.h>
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#include <assert.h>
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#include <ipxe/uaccess.h>
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#include <ipxe/gdbstub.h>
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#include <librm.h>
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#include <gdbmach.h>
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/** @file
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*
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* GDB architecture-specific bits for x86
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*
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*/
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/** Number of hardware breakpoints */
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#define NUM_HWBP 4
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/** Debug register 7: Global breakpoint enable */
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#define DR7_G( bp ) ( 2 << ( 2 * (bp) ) )
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/** Debug register 7: Global exact breakpoint enable */
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#define DR7_GE ( 1 << 9 )
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/** Debug register 7: Break on data writes */
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#define DR7_RWLEN_WRITE 0x11110000
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/** Debug register 7: Break on data access */
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#define DR7_RWLEN_ACCESS 0x33330000
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/** Debug register 7: One-byte length */
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#define DR7_RWLEN_1 0x00000000
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/** Debug register 7: Two-byte length */
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#define DR7_RWLEN_2 0x44440000
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/** Debug register 7: Four-byte length */
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#define DR7_RWLEN_4 0xcccc0000
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/** Debug register 7: Eight-byte length */
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#define DR7_RWLEN_8 0x88880000
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/** Debug register 7: Breakpoint R/W and length mask */
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#define DR7_RWLEN_MASK( bp ) ( 0xf0000 << ( 4 * (bp) ) )
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/** Hardware breakpoint addresses (debug registers 0-3) */
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static unsigned long dr[NUM_HWBP];
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/** Active value of debug register 7 */
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static unsigned long dr7 = DR7_GE;
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/**
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* Update debug registers
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*
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*/
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static void gdbmach_update ( void ) {
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/* Set debug registers */
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__asm__ __volatile__ ( "mov %0, %%dr0" : : "r" ( dr[0] ) );
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__asm__ __volatile__ ( "mov %0, %%dr1" : : "r" ( dr[1] ) );
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__asm__ __volatile__ ( "mov %0, %%dr2" : : "r" ( dr[2] ) );
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__asm__ __volatile__ ( "mov %0, %%dr3" : : "r" ( dr[3] ) );
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__asm__ __volatile__ ( "mov %0, %%dr7" : : "r" ( dr7 ) );
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}
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/**
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* Find reusable or available hardware breakpoint
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*
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* @v addr Linear address
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* @v rwlen Control bits
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* @ret bp Hardware breakpoint, or negative error
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*/
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static int gdbmach_find ( unsigned long addr, unsigned int rwlen ) {
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unsigned int i;
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int bp = -ENOENT;
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/* Look for a reusable or available breakpoint */
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for ( i = 0 ; i < NUM_HWBP ; i++ ) {
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/* If breakpoint is not enabled, then it is available */
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if ( ! ( dr7 & DR7_G ( i ) ) ) {
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bp = i;
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continue;
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}
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/* If breakpoint is enabled and has the same address
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* and control bits, then reuse it.
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*/
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if ( ( dr[i] == addr ) &&
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( ( ( dr7 ^ rwlen ) & DR7_RWLEN_MASK ( i ) ) == 0 ) ) {
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bp = i;
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break;
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}
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}
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return bp;
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}
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/**
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* Set hardware breakpoint
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*
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* @v type GDB breakpoint type
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* @v addr Virtual address
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* @v len Length
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* @v enable Enable (not disable) breakpoint
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* @ret rc Return status code
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*/
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int gdbmach_set_breakpoint ( int type, unsigned long addr, size_t len,
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int enable ) {
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unsigned int rwlen;
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unsigned long mask;
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int bp;
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/* Parse breakpoint type */
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switch ( type ) {
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case GDBMACH_WATCH:
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rwlen = DR7_RWLEN_WRITE;
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break;
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case GDBMACH_AWATCH:
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rwlen = DR7_RWLEN_ACCESS;
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break;
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default:
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return -ENOTSUP;
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}
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/* Parse breakpoint length */
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switch ( len ) {
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case 1:
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rwlen |= DR7_RWLEN_1;
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break;
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case 2:
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rwlen |= DR7_RWLEN_2;
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break;
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case 4:
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rwlen |= DR7_RWLEN_4;
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break;
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case 8:
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rwlen |= DR7_RWLEN_8;
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break;
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default:
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return -ENOTSUP;
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}
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/* Convert to linear address */
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if ( sizeof ( physaddr_t ) <= sizeof ( uint32_t ) )
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addr = virt_to_phys ( ( void * ) addr );
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/* Find reusable or available hardware breakpoint */
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bp = gdbmach_find ( addr, rwlen );
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if ( bp < 0 )
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return ( enable ? -ENOBUFS : 0 );
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/* Configure this breakpoint */
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DBGC ( &dr[0], "GDB bp %d at %p+%zx type %d (%sabled)\n",
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bp, ( ( void * ) addr ), len, type, ( enable ? "en" : "dis" ) );
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dr[bp] = addr;
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mask = DR7_RWLEN_MASK ( bp );
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dr7 = ( ( dr7 & ~mask ) | ( rwlen & mask ) );
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mask = DR7_G ( bp );
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dr7 &= ~mask;
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if ( enable )
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dr7 |= mask;
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/* Update debug registers */
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gdbmach_update();
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return 0;
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}
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/**
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* Handle exception
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*
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* @v signo GDB signal number
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* @v regs Register dump
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*/
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__asmcall void gdbmach_handler ( int signo, gdbreg_t *regs ) {
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unsigned long dr7_disabled = DR7_GE;
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unsigned long dr6_clear = 0;
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/* Temporarily disable breakpoints */
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__asm__ __volatile__ ( "mov %0, %%dr7\n" : : "r" ( dr7_disabled ) );
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/* Handle exception */
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DBGC ( &dr[0], "GDB signal %d\n", signo );
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DBGC2_HDA ( &dr[0], 0, regs, ( GDBMACH_NREGS * sizeof ( *regs ) ) );
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gdbstub_handler ( signo, regs );
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DBGC ( &dr[0], "GDB signal %d returning\n", signo );
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DBGC2_HDA ( &dr[0], 0, regs, ( GDBMACH_NREGS * sizeof ( *regs ) ) );
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/* Clear breakpoint status register */
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__asm__ __volatile__ ( "mov %0, %%dr6\n" : : "r" ( dr6_clear ) );
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/* Re-enable breakpoints */
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__asm__ __volatile__ ( "mov %0, %%dr7\n" : : "r" ( dr7 ) );
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}
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/**
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* CPU exception vectors
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*
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* Note that we cannot intercept anything from INT8 (double fault)
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* upwards, since these overlap by default with IRQ0-7.
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*/
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static void * gdbmach_vectors[] = {
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gdbmach_sigfpe, /* Divide by zero */
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gdbmach_sigtrap, /* Debug trap */
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NULL, /* Non-maskable interrupt */
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gdbmach_sigtrap, /* Breakpoint */
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gdbmach_sigstkflt, /* Overflow */
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gdbmach_sigstkflt, /* Bound range exceeded */
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gdbmach_sigill, /* Invalid opcode */
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};
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/**
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* Initialise GDB
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*/
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void gdbmach_init ( void ) {
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unsigned int i;
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/* Hook CPU exception vectors */
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for ( i = 0 ; i < ( sizeof ( gdbmach_vectors ) /
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sizeof ( gdbmach_vectors[0] ) ) ; i++ ) {
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if ( gdbmach_vectors[i] )
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set_interrupt_vector ( i, gdbmach_vectors[i] );
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}
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}
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