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