GDB architecture-specific bits for x86. More...

#include <stddef.h>
#include <stdio.h>
#include <errno.h>
#include <assert.h>
#include <ipxe/uaccess.h>
#include <ipxe/gdbstub.h>
#include <librm.h>

Macros
#define	NUM_HWBP 4
	Number of hardware breakpoints. More...

#define	DR7_G(bp) ( 2 << ( 2 * (bp) ) )
	Debug register 7: Global breakpoint enable. More...

#define	DR7_GE ( 1 << 9 )
	Debug register 7: Global exact breakpoint enable. More...

#define	DR7_RWLEN_WRITE 0x11110000
	Debug register 7: Break on data writes. More...

#define	DR7_RWLEN_ACCESS 0x33330000
	Debug register 7: Break on data access. More...

#define	DR7_RWLEN_1 0x00000000
	Debug register 7: One-byte length. More...

#define	DR7_RWLEN_2 0x44440000
	Debug register 7: Two-byte length. More...

#define	DR7_RWLEN_4 0xcccc0000
	Debug register 7: Four-byte length. More...

#define	DR7_RWLEN_8 0x88880000
	Debug register 7: Eight-byte length. More...

#define	DR7_RWLEN_MASK(bp) ( 0xf0000 << ( 4 * (bp) ) )
	Debug register 7: Breakpoint R/W and length mask. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)

static void	gdbmach_update (void)
	Update debug registers. More...

static int	gdbmach_find (unsigned long addr, unsigned int rwlen)
	Find reusable or available hardware breakpoint. More...

int	gdbmach_set_breakpoint (int type, unsigned long addr, size_t len, int enable)
	Set hardware breakpoint. More...

__asmcall void	gdbmach_handler (int signo, gdbreg_t *regs)
	Handle exception. More...

void	gdbmach_init (void)
	Initialise GDB. More...

Variables
static unsigned long	dr [NUM_HWBP]
	Hardware breakpoint addresses (debug registers 0-3) More...

static unsigned long	dr7 = DR7_GE
	Active value of debug register 7. More...

static void *	gdbmach_vectors []
	CPU exception vectors. More...

Detailed Description

GDB architecture-specific bits for x86.

Definition in file gdbmach.c.

Macro Definition Documentation

◆ NUM_HWBP

#define NUM_HWBP 4

Number of hardware breakpoints.

Definition at line 42 of file gdbmach.c.

◆ DR7_G

#define DR7_G ( bp ) ( 2 << ( 2 * (bp) ) )

Debug register 7: Global breakpoint enable.

Definition at line 45 of file gdbmach.c.

◆ DR7_GE

#define DR7_GE ( 1 << 9 )

Debug register 7: Global exact breakpoint enable.

Definition at line 48 of file gdbmach.c.

◆ DR7_RWLEN_WRITE

#define DR7_RWLEN_WRITE 0x11110000

Debug register 7: Break on data writes.

Definition at line 51 of file gdbmach.c.

◆ DR7_RWLEN_ACCESS

#define DR7_RWLEN_ACCESS 0x33330000

Debug register 7: Break on data access.

Definition at line 54 of file gdbmach.c.

◆ DR7_RWLEN_1

#define DR7_RWLEN_1 0x00000000

Debug register 7: One-byte length.

Definition at line 57 of file gdbmach.c.

◆ DR7_RWLEN_2

#define DR7_RWLEN_2 0x44440000

Debug register 7: Two-byte length.

Definition at line 60 of file gdbmach.c.

◆ DR7_RWLEN_4

#define DR7_RWLEN_4 0xcccc0000

Debug register 7: Four-byte length.

Definition at line 63 of file gdbmach.c.

◆ DR7_RWLEN_8

#define DR7_RWLEN_8 0x88880000

Debug register 7: Eight-byte length.

Definition at line 66 of file gdbmach.c.

◆ DR7_RWLEN_MASK

#define DR7_RWLEN_MASK ( bp ) ( 0xf0000 << ( 4 * (bp) ) )

Debug register 7: Breakpoint R/W and length mask.

Definition at line 69 of file gdbmach.c.

Function Documentation

◆ FILE_LICENCE()

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL )

◆ gdbmach_update()

static void gdbmach_update ( void )

static

Update debug registers.

Definition at line 81 of file gdbmach.c.

                                     {
 
         /* 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 ) );
 }

References __asm__(), __volatile__(), dr, and dr7.

Referenced by gdbmach_set_breakpoint().

◆ gdbmach_find()

static int gdbmach_find	(	unsigned long	addr,
		unsigned int	rwlen
	)

static

Find reusable or available hardware breakpoint.

Parameters

addr	Linear address
rwlen	Control bits

Return values

bp	Hardware breakpoint, or negative error

Definition at line 98 of file gdbmach.c.

                                                                    {
         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;
 }

References addr, bp, dr, dr7, DR7_G, DR7_RWLEN_MASK, ENOENT, and NUM_HWBP.

Referenced by gdbmach_set_breakpoint().

◆ gdbmach_set_breakpoint()

int gdbmach_set_breakpoint	(	int	type,
		unsigned long	addr,
		size_t	len,
		int	enable
	)

Set hardware breakpoint.

Parameters

type	GDB breakpoint type
addr	Virtual address
len	Length
enable	Enable (not disable) breakpoint

Return values

rc	Return status code

Definition at line 133 of file gdbmach.c.

                                           {
         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;
 }

References addr, bp, DBGC, dr, dr7, DR7_G, DR7_RWLEN_1, DR7_RWLEN_2, DR7_RWLEN_4, DR7_RWLEN_8, DR7_RWLEN_ACCESS, DR7_RWLEN_MASK, DR7_RWLEN_WRITE, ENOBUFS, ENOTSUP, GDBMACH_AWATCH, gdbmach_find(), gdbmach_update(), GDBMACH_WATCH, len, type, and virt_to_phys().

Referenced by gdbstub_breakpoint().

◆ gdbmach_handler()

__asmcall void gdbmach_handler	(	int	signo,
		gdbreg_t *	regs
	)

Handle exception.

Parameters

signo	GDB signal number
regs	Register dump

Definition at line 201 of file gdbmach.c.

                                                              {
         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 ) );
 }

References __asm__(), __volatile__(), DBGC, DBGC2_HDA, dr, dr7, DR7_GE, GDBMACH_NREGS, gdbstub_handler(), and regs.

◆ gdbmach_init()

void gdbmach_init ( void )

Initialise GDB.

Definition at line 241 of file gdbmach.c.

                            {
         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] );
         }
 }

References gdbmach_vectors, and set_interrupt_vector().

Referenced by gdbstub_start().

Variable Documentation

◆ dr

unsigned long dr[NUM_HWBP]

static

Hardware breakpoint addresses (debug registers 0-3)

Definition at line 72 of file gdbmach.c.

Referenced by gdbmach_find(), gdbmach_handler(), gdbmach_set_breakpoint(), and gdbmach_update().

◆ dr7

unsigned long dr7 = DR7_GE

static

Active value of debug register 7.

Definition at line 75 of file gdbmach.c.

Referenced by gdbmach_find(), gdbmach_handler(), gdbmach_set_breakpoint(), and gdbmach_update().

◆ gdbmach_vectors

void* gdbmach_vectors[]

static

Initial value:

= {
        gdbmach_sigfpe,         
        gdbmach_sigtrap,        
        NULL,                   
        gdbmach_sigtrap,        
        gdbmach_sigstkflt,      
        gdbmach_sigstkflt,      
        gdbmach_sigill,         
}

CPU exception vectors.

Note that we cannot intercept anything from INT8 (double fault) upwards, since these overlap by default with IRQ0-7.

Definition at line 228 of file gdbmach.c.

Referenced by gdbmach_init().

Macros

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ NUM_HWBP

◆ DR7_G

◆ DR7_GE

◆ DR7_RWLEN_WRITE

◆ DR7_RWLEN_ACCESS

◆ DR7_RWLEN_1

◆ DR7_RWLEN_2

◆ DR7_RWLEN_4

◆ DR7_RWLEN_8

◆ DR7_RWLEN_MASK

Function Documentation

◆ FILE_LICENCE()

◆ gdbmach_update()

◆ gdbmach_find()

◆ gdbmach_set_breakpoint()

◆ gdbmach_handler()

◆ gdbmach_init()

Variable Documentation

◆ dr

◆ dr7

◆ gdbmach_vectors