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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2025, Oracle and/or its affiliates.
*/
#include <objtool/trace.h>
bool trace;
int trace_depth;
/*
* Macros to trace CFI state attributes changes.
*/
#define TRACE_CFI_ATTR(attr, prev, next, fmt, ...) \
({ \
if ((prev)->attr != (next)->attr) \
TRACE("%s=" fmt " ", #attr, __VA_ARGS__); \
})
#define TRACE_CFI_ATTR_BOOL(attr, prev, next) \
TRACE_CFI_ATTR(attr, prev, next, \
"%s", (next)->attr ? "true" : "false")
#define TRACE_CFI_ATTR_NUM(attr, prev, next, fmt) \
TRACE_CFI_ATTR(attr, prev, next, fmt, (next)->attr)
#define CFI_REG_NAME_MAXLEN 16
/*
* Return the name of a register. Note that the same static buffer
* is returned if the name is dynamically generated.
*/
static const char *cfi_reg_name(unsigned int reg)
{
static char rname_buffer[CFI_REG_NAME_MAXLEN];
const char *rname;
switch (reg) {
case CFI_UNDEFINED:
return "<undefined>";
case CFI_CFA:
return "cfa";
case CFI_SP_INDIRECT:
return "(sp)";
case CFI_BP_INDIRECT:
return "(bp)";
}
if (reg < CFI_NUM_REGS) {
rname = arch_reg_name[reg];
if (rname)
return rname;
}
if (snprintf(rname_buffer, CFI_REG_NAME_MAXLEN, "r%d", reg) == -1)
return "<error>";
return (const char *)rname_buffer;
}
/*
* Functions and macros to trace CFI registers changes.
*/
static void trace_cfi_reg(const char *prefix, int reg, const char *fmt,
int base_prev, int offset_prev,
int base_next, int offset_next)
{
char *rname;
if (base_prev == base_next && offset_prev == offset_next)
return;
if (prefix)
TRACE("%s:", prefix);
if (base_next == CFI_UNDEFINED) {
TRACE("%1$s=<undef> ", cfi_reg_name(reg));
} else {
rname = strdup(cfi_reg_name(reg));
TRACE(fmt, rname, cfi_reg_name(base_next), offset_next);
free(rname);
}
}
static void trace_cfi_reg_val(const char *prefix, int reg,
int base_prev, int offset_prev,
int base_next, int offset_next)
{
trace_cfi_reg(prefix, reg, "%1$s=%2$s%3$+d ",
base_prev, offset_prev, base_next, offset_next);
}
static void trace_cfi_reg_ref(const char *prefix, int reg,
int base_prev, int offset_prev,
int base_next, int offset_next)
{
trace_cfi_reg(prefix, reg, "%1$s=(%2$s%3$+d) ",
base_prev, offset_prev, base_next, offset_next);
}
#define TRACE_CFI_REG_VAL(reg, prev, next) \
trace_cfi_reg_val(NULL, reg, prev.base, prev.offset, \
next.base, next.offset)
#define TRACE_CFI_REG_REF(reg, prev, next) \
trace_cfi_reg_ref(NULL, reg, prev.base, prev.offset, \
next.base, next.offset)
void trace_insn_state(struct instruction *insn, struct insn_state *sprev,
struct insn_state *snext)
{
struct cfi_state *cprev, *cnext;
int i;
if (!memcmp(sprev, snext, sizeof(struct insn_state)))
return;
cprev = &sprev->cfi;
cnext = &snext->cfi;
disas_print_insn(stderr, objtool_disas_ctx, insn,
trace_depth - 1, "state: ");
/* print registers changes */
TRACE_CFI_REG_VAL(CFI_CFA, cprev->cfa, cnext->cfa);
for (i = 0; i < CFI_NUM_REGS; i++) {
TRACE_CFI_REG_VAL(i, cprev->vals[i], cnext->vals[i]);
TRACE_CFI_REG_REF(i, cprev->regs[i], cnext->regs[i]);
}
/* print attributes changes */
TRACE_CFI_ATTR_NUM(stack_size, cprev, cnext, "%d");
TRACE_CFI_ATTR_BOOL(drap, cprev, cnext);
if (cnext->drap) {
trace_cfi_reg_val("drap", cnext->drap_reg,
cprev->drap_reg, cprev->drap_offset,
cnext->drap_reg, cnext->drap_offset);
}
TRACE_CFI_ATTR_BOOL(bp_scratch, cprev, cnext);
TRACE_CFI_ATTR_NUM(instr, sprev, snext, "%d");
TRACE_CFI_ATTR_NUM(uaccess_stack, sprev, snext, "%u");
TRACE("\n");
insn->trace = 1;
}
void trace_alt_begin(struct instruction *orig_insn, struct alternative *alt,
char *alt_name)
{
struct instruction *alt_insn;
char suffix[2];
alt_insn = alt->insn;
if (alt->type == ALT_TYPE_EX_TABLE) {
/*
* When there is an exception table then the instruction
* at the original location is executed but it can cause
* an exception. In that case, the execution will be
* redirected to the alternative instruction.
*
* The instruction at the original location can have
* instruction alternatives, so we just print the location
* of the instruction that can cause the exception and
* not the instruction itself.
*/
TRACE_ALT_INFO_NOADDR(orig_insn, "/ ", "%s for instruction at 0x%lx <%s+0x%lx>",
alt_name,
orig_insn->offset, orig_insn->sym->name,
orig_insn->offset - orig_insn->sym->offset);
} else {
TRACE_ALT_INFO_NOADDR(orig_insn, "/ ", "%s", alt_name);
}
if (alt->type == ALT_TYPE_JUMP_TABLE) {
/*
* For a jump alternative, if the default instruction is
* a NOP then it is replaced with the jmp instruction,
* otherwise it is replaced with a NOP instruction.
*/
trace_depth++;
if (orig_insn->type == INSN_NOP) {
suffix[0] = (orig_insn->len == 5) ? 'q' : '\0';
TRACE_ADDR(orig_insn, "jmp%-3s %lx <%s+0x%lx>", suffix,
alt_insn->offset, alt_insn->sym->name,
alt_insn->offset - alt_insn->sym->offset);
} else {
TRACE_ADDR(orig_insn, "nop%d", orig_insn->len);
trace_depth--;
}
}
}
void trace_alt_end(struct instruction *orig_insn, struct alternative *alt,
char *alt_name)
{
if (alt->type == ALT_TYPE_JUMP_TABLE && orig_insn->type == INSN_NOP)
trace_depth--;
TRACE_ALT_INFO_NOADDR(orig_insn, "\\ ", "%s", alt_name);
}
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