/* Show a location */
static int convert_location(Dwarf_Op *op, struct probe_finder *pf)
{
unsigned int regn;
Dwarf_Word offs = 0;
bool ref = false;
const char *regs;
struct kprobe_trace_arg *tvar = pf->tvar;
/* If this is based on frame buffer, set the offset */
if (op->atom == DW_OP_fbreg) {
if (pf->fb_ops == NULL) {
pr_warning("The attribute of frame base is not "
"supported.\n");
return -ENOTSUP;
}
ref = true;
offs = op->number;
op = &pf->fb_ops[0];
}
if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
regn = op->atom - DW_OP_breg0;
offs += op->number;
ref = true;
} else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
regn = op->atom - DW_OP_reg0;
} else if (op->atom == DW_OP_bregx) {
regn = op->number;
offs += op->number2;
ref = true;
} else if (op->atom == DW_OP_regx) {
regn = op->number;
} else {
pr_warning("DW_OP %x is not supported.\n", op->atom);
return -ENOTSUP;
}
regs = get_arch_regstr(regn);
if (!regs) {
pr_warning("Mapping for DWARF register number %u missing on this architecture.", regn);
return -ERANGE;
}
tvar->value = strdup(regs);
if (tvar->value == NULL)
return -ENOMEM;
if (ref) {
tvar->ref = zalloc(sizeof(struct kprobe_trace_arg_ref));
if (tvar->ref == NULL)
return -ENOMEM;
tvar->ref->offset = (long)offs;
}
return 0;
}
static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
Dwarf_Op *fb_ops,
struct probe_trace_arg *tvar)
{
Dwarf_Attribute attr;
Dwarf_Op *op;
size_t nops;
unsigned int regn;
Dwarf_Word offs = 0;
bool ref = false;
const char *regs;
int ret;
if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
goto static_var;
if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL ||
dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0 ||
nops == 0) {
return -ENOENT;
}
if (op->atom == DW_OP_addr) {
static_var:
if (!tvar)
return 0;
ret = strlen(dwarf_diename(vr_die));
tvar->value = zalloc(ret + 2);
if (tvar->value == NULL)
return -ENOMEM;
snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
tvar->ref = alloc_trace_arg_ref((long)offs);
if (tvar->ref == NULL)
return -ENOMEM;
return 0;
}
if (op->atom == DW_OP_fbreg) {
if (fb_ops == NULL)
return -ENOTSUP;
ref = true;
offs = op->number;
op = &fb_ops[0];
}
if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
regn = op->atom - DW_OP_breg0;
offs += op->number;
ref = true;
} else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
regn = op->atom - DW_OP_reg0;
} else if (op->atom == DW_OP_bregx) {
regn = op->number;
offs += op->number2;
ref = true;
} else if (op->atom == DW_OP_regx) {
regn = op->number;
} else {
pr_debug("DW_OP %x is not supported.\n", op->atom);
return -ENOTSUP;
}
if (!tvar)
return 0;
regs = get_arch_regstr(regn);
if (!regs) {
pr_warning("Mapping for the register number %u "
"missing on this architecture.\n", regn);
return -ERANGE;
}
tvar->value = strdup(regs);
if (tvar->value == NULL)
return -ENOMEM;
if (ref) {
tvar->ref = alloc_trace_arg_ref((long)offs);
if (tvar->ref == NULL)
return -ENOMEM;
}
return 0;
}
/*
* Convert a location into trace_arg.
* If tvar == NULL, this just checks variable can be converted.
* If fentry == true and vr_die is a parameter, do huristic search
* for the location fuzzed by function entry mcount.
*/
static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
struct probe_trace_arg *tvar)
{
Dwarf_Attribute attr;
Dwarf_Addr tmp = 0;
Dwarf_Op *op;
size_t nops;
unsigned int regn;
Dwarf_Word offs = 0;
bool ref = false;
const char *regs;
int ret;
if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
goto static_var;
/* TODO: handle more than 1 exprs */
if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
return -EINVAL; /* Broken DIE ? */
if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
ret = dwarf_entrypc(sp_die, &tmp);
if (ret || addr != tmp ||
dwarf_tag(vr_die) != DW_TAG_formal_parameter ||
dwarf_highpc(sp_die, &tmp))
return -ENOENT;
/*
* This is fuzzed by fentry mcount. We try to find the
* parameter location at the earliest address.
*/
for (addr += 1; addr <= tmp; addr++) {
if (dwarf_getlocation_addr(&attr, addr, &op,
&nops, 1) > 0)
goto found;
}
return -ENOENT;
}
found:
if (nops == 0)
/* TODO: Support const_value */
return -ENOENT;
if (op->atom == DW_OP_addr) {
static_var:
if (!tvar)
return 0;
/* Static variables on memory (not stack), make @varname */
ret = strlen(dwarf_diename(vr_die));
tvar->value = zalloc(ret + 2);
if (tvar->value == NULL)
return -ENOMEM;
snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
tvar->ref = alloc_trace_arg_ref((long)offs);
if (tvar->ref == NULL)
return -ENOMEM;
return 0;
}
/* If this is based on frame buffer, set the offset */
if (op->atom == DW_OP_fbreg) {
if (fb_ops == NULL)
return -ENOTSUP;
ref = true;
offs = op->number;
op = &fb_ops[0];
}
if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
regn = op->atom - DW_OP_breg0;
offs += op->number;
ref = true;
} else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
regn = op->atom - DW_OP_reg0;
} else if (op->atom == DW_OP_bregx) {
regn = op->number;
offs += op->number2;
ref = true;
} else if (op->atom == DW_OP_regx) {
regn = op->number;
} else {
pr_debug("DW_OP %x is not supported.\n", op->atom);
return -ENOTSUP;
}
if (!tvar)
return 0;
regs = get_arch_regstr(regn);
if (!regs) {
/* This should be a bug in DWARF or this tool */
pr_warning("Mapping for the register number %u "
"missing on this architecture.\n", regn);
return -ERANGE;
}
tvar->value = strdup(regs);
if (tvar->value == NULL)
return -ENOMEM;
if (ref) {
tvar->ref = alloc_trace_arg_ref((long)offs);
if (tvar->ref == NULL)
return -ENOMEM;
}
return 0;
}
