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u-boot/arch/powerpc/lib/kgdb.c
Wolfgang Denk 54841ab50c Make sure that argv[] argument pointers are not modified. 
The hush shell dynamically allocates (and re-allocates) memory for the
argument strings in the "char *argv[]" argument vector passed to
commands.  Any code that modifies these pointers will cause serious
corruption of the malloc data structures and crash U-Boot, so make
sure the compiler can check that no such modifications are being done
by changing the code into "char * const argv[]".

This modification is the result of debugging a strange crash caused
after adding a new command, which used the following argument
processing code which has been working perfectly fine in all Unix
systems since version 6 - but not so in U-Boot:

int main (int argc, char **argv)
{
	while (--argc > 0 && **++argv == '-') {
/* ====> */	while (*++*argv) {
			switch (**argv) {
			case 'd':
				debug++;
				break;
			...
			default:
				usage ();
			}
		}
	}
	...
}

The line marked "====>" will corrupt the malloc data structures and
usually cause U-Boot to crash when the next command gets executed by
the shell.  With the modification, the compiler will prevent this with
an
	error: increment of read-only location '*argv'

N.B.: The code above can be trivially rewritten like this:

	while (--argc > 0 && **++argv == '-') {
		char *arg = *argv;
		while (*++arg) {
			switch (*arg) {
			...

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
2010-07-04 23:55:42 +02:00

321 lines
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#include <common.h>
#include <command.h>
#include <kgdb.h>
#include <asm/signal.h>
#include <asm/processor.h>
#define PC_REGNUM 64
#define SP_REGNUM 1
void breakinst(void);
int
kgdb_setjmp(long *buf)
{
asm ("mflr 0; stw 0,0(%0);"
"stw 1,4(%0); stw 2,8(%0);"
"mfcr 0; stw 0,12(%0);"
"stmw 13,16(%0)"
: : "r" (buf));
/* XXX should save fp regs as well */
return 0;
}
void
kgdb_longjmp(long *buf, int val)
{
if (val == 0)
val = 1;
asm ("lmw 13,16(%0);"
"lwz 0,12(%0); mtcrf 0x38,0;"
"lwz 0,0(%0); lwz 1,4(%0); lwz 2,8(%0);"
"mtlr 0; mr 3,%1"
: : "r" (buf), "r" (val));
}
static inline unsigned long
get_msr(void)
{
unsigned long msr;
asm volatile("mfmsr %0" : "=r" (msr):);
return msr;
}
static inline void
set_msr(unsigned long msr)
{
asm volatile("mtmsr %0" : : "r" (msr));
}
/* Convert the SPARC hardware trap type code to a unix signal number. */
/*
* This table contains the mapping between PowerPC hardware trap types, and
* signals, which are primarily what GDB understands.
*/
static struct hard_trap_info
{
unsigned int tt; /* Trap type code for powerpc */
unsigned char signo; /* Signal that we map this trap into */
} hard_trap_info[] = {
{ 0x200, SIGSEGV }, /* machine check */
{ 0x300, SIGSEGV }, /* address error (store) */
{ 0x400, SIGBUS }, /* instruction bus error */
{ 0x500, SIGINT }, /* interrupt */
{ 0x600, SIGBUS }, /* alingment */
{ 0x700, SIGTRAP }, /* breakpoint trap */
{ 0x800, SIGFPE }, /* fpu unavail */
{ 0x900, SIGALRM }, /* decrementer */
{ 0xa00, SIGILL }, /* reserved */
{ 0xb00, SIGILL }, /* reserved */
{ 0xc00, SIGCHLD }, /* syscall */
{ 0xd00, SIGTRAP }, /* single-step/watch */
{ 0xe00, SIGFPE }, /* fp assist */
{ 0, 0} /* Must be last */
};
static int
computeSignal(unsigned int tt)
{
struct hard_trap_info *ht;
for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
if (ht->tt == tt)
return ht->signo;
return SIGHUP; /* default for things we don't know about */
}
void
kgdb_enter(struct pt_regs *regs, kgdb_data *kdp)
{
unsigned long msr;
kdp->private[0] = msr = get_msr();
set_msr(msr & ~MSR_EE); /* disable interrupts */
if (regs->nip == (unsigned long)breakinst) {
/* Skip over breakpoint trap insn */
regs->nip += 4;
}
regs->msr &= ~MSR_SE;
/* reply to host that an exception has occurred */
kdp->sigval = computeSignal(regs->trap);
kdp->nregs = 2;
kdp->regs[0].num = PC_REGNUM;
kdp->regs[0].val = regs->nip;
kdp->regs[1].num = SP_REGNUM;
kdp->regs[1].val = regs->gpr[SP_REGNUM];
}
void
kgdb_exit(struct pt_regs *regs, kgdb_data *kdp)
{
unsigned long msr = kdp->private[0];
if (kdp->extype & KGDBEXIT_WITHADDR)
regs->nip = kdp->exaddr;
switch (kdp->extype & KGDBEXIT_TYPEMASK) {
case KGDBEXIT_KILL:
case KGDBEXIT_CONTINUE:
set_msr(msr);
break;
case KGDBEXIT_SINGLE:
regs->msr |= MSR_SE;
#if 0
set_msr(msr | MSR_SE);
#endif
break;
}
}
int
kgdb_trap(struct pt_regs *regs)
{
return (regs->trap);
}
/* return the value of the CPU registers.
* some of them are non-PowerPC names :(
* they are stored in gdb like:
* struct {
* u32 gpr[32];
* f64 fpr[32];
* u32 pc, ps, cnd, lr; (ps=msr)
* u32 cnt, xer, mq;
* }
*/
#define SPACE_REQUIRED ((32*4)+(32*8)+(6*4))
#ifdef CONFIG_8260
/* store floating double indexed */
#define STFDI(n,p) __asm__ __volatile__ ("stfd " #n ",%0" : "=o"(p[2*n]))
/* store floating double multiple */
#define STFDM(p) { STFDI( 0,p); STFDI( 1,p); STFDI( 2,p); STFDI( 3,p); \
STFDI( 4,p); STFDI( 5,p); STFDI( 6,p); STFDI( 7,p); \
STFDI( 8,p); STFDI( 9,p); STFDI(10,p); STFDI(11,p); \
STFDI(12,p); STFDI(13,p); STFDI(14,p); STFDI(15,p); \
STFDI(16,p); STFDI(17,p); STFDI(18,p); STFDI(19,p); \
STFDI(20,p); STFDI(21,p); STFDI(22,p); STFDI(23,p); \
STFDI(24,p); STFDI(25,p); STFDI(26,p); STFDI(27,p); \
STFDI(28,p); STFDI(29,p); STFDI(30,p); STFDI(31,p); }
#endif
int
kgdb_getregs(struct pt_regs *regs, char *buf, int max)
{
int i;
unsigned long *ptr = (unsigned long *)buf;
if (max < SPACE_REQUIRED)
kgdb_error(KGDBERR_NOSPACE);
if ((unsigned long)ptr & 3)
kgdb_error(KGDBERR_ALIGNFAULT);
/* General Purpose Regs */
for (i = 0; i < 32; i++)
*ptr++ = regs->gpr[i];
/* Floating Point Regs */
#ifdef CONFIG_8260
STFDM(ptr);
ptr += 32*2;
#else
for (i = 0; i < 32; i++) {
*ptr++ = 0;
*ptr++ = 0;
}
#endif
/* pc, msr, cr, lr, ctr, xer, (mq is unused) */
*ptr++ = regs->nip;
*ptr++ = regs->msr;
*ptr++ = regs->ccr;
*ptr++ = regs->link;
*ptr++ = regs->ctr;
*ptr++ = regs->xer;
return (SPACE_REQUIRED);
}
/* set the value of the CPU registers */
#ifdef CONFIG_8260
/* load floating double */
#define LFD(n,v) __asm__ __volatile__ ("lfd " #n ",%0" :: "o"(v))
/* load floating double indexed */
#define LFDI(n,p) __asm__ __volatile__ ("lfd " #n ",%0" :: "o"((p)[2*n]))
/* load floating double multiple */
#define LFDM(p) { LFDI( 0,p); LFDI( 1,p); LFDI( 2,p); LFDI( 3,p); \
LFDI( 4,p); LFDI( 5,p); LFDI( 6,p); LFDI( 7,p); \
LFDI( 8,p); LFDI( 9,p); LFDI(10,p); LFDI(11,p); \
LFDI(12,p); LFDI(13,p); LFDI(14,p); LFDI(15,p); \
LFDI(16,p); LFDI(17,p); LFDI(18,p); LFDI(19,p); \
LFDI(20,p); LFDI(21,p); LFDI(22,p); LFDI(23,p); \
LFDI(24,p); LFDI(25,p); LFDI(26,p); LFDI(27,p); \
LFDI(28,p); LFDI(29,p); LFDI(30,p); LFDI(31,p); }
#endif
void
kgdb_putreg(struct pt_regs *regs, int regno, char *buf, int length)
{
unsigned long *ptr = (unsigned long *)buf;
if (regno < 0 || regno >= 70)
kgdb_error(KGDBERR_BADPARAMS);
else if (regno >= 32 && regno < 64) {
if (length < 8)
kgdb_error(KGDBERR_NOSPACE);
}
else {
if (length < 4)
kgdb_error(KGDBERR_NOSPACE);
}
if ((unsigned long)ptr & 3)
kgdb_error(KGDBERR_ALIGNFAULT);
if (regno >= 0 && regno < 32)
regs->gpr[regno] = *ptr;
else switch (regno) {
#ifdef CONFIG_8260
#define caseF(n) \
case (n) + 32: LFD(n, *ptr); break;
caseF( 0) caseF( 1) caseF( 2) caseF( 3) caseF( 4) caseF( 5) caseF( 6) caseF( 7)
caseF( 8) caseF( 9) caseF(10) caseF(11) caseF(12) caseF(13) caseF(14) caseF(15)
caseF(16) caseF(17) caseF(18) caseF(19) caseF(20) caseF(21) caseF(22) caseF(23)
caseF(24) caseF(25) caseF(26) caseF(27) caseF(28) caseF(29) caseF(30) caseF(31)
#undef caseF
#endif
case 64: regs->nip = *ptr; break;
case 65: regs->msr = *ptr; break;
case 66: regs->ccr = *ptr; break;
case 67: regs->link = *ptr; break;
case 68: regs->ctr = *ptr; break;
case 69: regs->ctr = *ptr; break;
default:
kgdb_error(KGDBERR_BADPARAMS);
}
}
void
kgdb_putregs(struct pt_regs *regs, char *buf, int length)
{
int i;
unsigned long *ptr = (unsigned long *)buf;
if (length < SPACE_REQUIRED)
kgdb_error(KGDBERR_NOSPACE);
if ((unsigned long)ptr & 3)
kgdb_error(KGDBERR_ALIGNFAULT);
/*
* If the stack pointer has moved, you should pray.
* (cause only god can help you).
*/
/* General Purpose Regs */
for (i = 0; i < 32; i++)
regs->gpr[i] = *ptr++;
/* Floating Point Regs */
#ifdef CONFIG_8260
LFDM(ptr);
#endif
ptr += 32*2;
/* pc, msr, cr, lr, ctr, xer, (mq is unused) */
regs->nip = *ptr++;
regs->msr = *ptr++;
regs->ccr = *ptr++;
regs->link = *ptr++;
regs->ctr = *ptr++;
regs->xer = *ptr++;
}
/* This function will generate a breakpoint exception. It is used at the
beginning of a program to sync up with a debugger and can be used
otherwise as a quick means to stop program execution and "break" into
the debugger. */
void
kgdb_breakpoint(int argc, char * const argv[])
{
asm(" .globl breakinst\n\
breakinst: .long 0x7d821008\n\
");
}
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