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objtool: Implement stack validation 2.0

Browse Source 
This is a major rewrite of objtool.  Instead of only tracking frame
pointer changes, it now tracks all stack-related operations, including
all register saves/restores.

In addition to making stack validation more robust, this also paves the
way for undwarf generation.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/678bd94c0566c6129bcc376cddb259c4c5633004.1498659915.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf
2017-06-28 10:11:07 -05:00
committed by Ingo Molnar
parent c207aee480
commit baa41469a7
11 changed files with 1133 additions and 323 deletions
Download Patch File Download Diff File Expand all files Collapse all files

676
tools/objtool/check.c
View File

@@ -27,10 +27,6 @@
#include <linux/hashtable.h>
#include <linux/kernel.h>
#define STATE_FP_SAVED 0x1
#define STATE_FP_SETUP 0x2
#define STATE_FENTRY 0x4
struct alternative {
struct list_head list;
struct instruction *insn;
@@ -38,6 +34,7 @@ struct alternative {
const char *objname;
static bool nofp;
struct cfi_state initial_func_cfi;
static struct instruction *find_insn(struct objtool_file *file,
struct section *sec, unsigned long offset)
@@ -56,7 +53,7 @@ static struct instruction *next_insn_same_sec(struct objtool_file *file,
{
struct instruction *next = list_next_entry(insn, list);
if (&next->list == &file->insn_list || next->sec != insn->sec)
if (!next || &next->list == &file->insn_list || next->sec != insn->sec)
return NULL;
return next;
@@ -67,7 +64,7 @@ static bool gcov_enabled(struct objtool_file *file)
struct section *sec;
struct symbol *sym;
list_for_each_entry(sec, &file->elf->sections, list)
for_each_sec(file, sec)
list_for_each_entry(sym, &sec->symbol_list, list)
if (!strncmp(sym->name, "__gcov_.", 8))
return true;
@@ -75,9 +72,6 @@ static bool gcov_enabled(struct objtool_file *file)
return false;
}
#define for_each_insn(file, insn) \
list_for_each_entry(insn, &file->insn_list, list)
#define func_for_each_insn(file, func, insn) \
for (insn = find_insn(file, func->sec, func->offset); \
insn && &insn->list != &file->insn_list && \
@@ -94,6 +88,9 @@ static bool gcov_enabled(struct objtool_file *file)
#define sec_for_each_insn_from(file, insn) \
for (; insn; insn = next_insn_same_sec(file, insn))
#define sec_for_each_insn_continue(file, insn) \
for (insn = next_insn_same_sec(file, insn); insn; \
insn = next_insn_same_sec(file, insn))
/*
* Check if the function has been manually whitelisted with the
@@ -103,7 +100,6 @@ static bool gcov_enabled(struct objtool_file *file)
static bool ignore_func(struct objtool_file *file, struct symbol *func)
{
struct rela *rela;
struct instruction *insn;
/* check for STACK_FRAME_NON_STANDARD */
if (file->whitelist && file->whitelist->rela)
@@ -116,11 +112,6 @@ static bool ignore_func(struct objtool_file *file, struct symbol *func)
return true;
}
/* check if it has a context switching instruction */
func_for_each_insn(file, func, insn)
if (insn->type == INSN_CONTEXT_SWITCH)
return true;
return false;
}
@@ -234,6 +225,17 @@ static int dead_end_function(struct objtool_file *file, struct symbol *func)
return __dead_end_function(file, func, 0);
}
static void clear_insn_state(struct insn_state *state)
{
int i;
memset(state, 0, sizeof(*state));
state->cfa.base = CFI_UNDEFINED;
for (i = 0; i < CFI_NUM_REGS; i++)
state->regs[i].base = CFI_UNDEFINED;
state->drap_reg = CFI_UNDEFINED;
}
/*
* Call the arch-specific instruction decoder for all the instructions and add
* them to the global instruction list.
@@ -246,23 +248,29 @@ static int decode_instructions(struct objtool_file *file)
struct instruction *insn;
int ret;
list_for_each_entry(sec, &file->elf->sections, list) {
for_each_sec(file, sec) {
if (!(sec->sh.sh_flags & SHF_EXECINSTR))
continue;
for (offset = 0; offset < sec->len; offset += insn->len) {
insn = malloc(sizeof(*insn));
if (!insn) {
WARN("malloc failed");
return -1;
}
memset(insn, 0, sizeof(*insn));
INIT_LIST_HEAD(&insn->alts);
clear_insn_state(&insn->state);
insn->sec = sec;
insn->offset = offset;
ret = arch_decode_instruction(file->elf, sec, offset,
sec->len - offset,
&insn->len, &insn->type,
&insn->immediate);
&insn->immediate,
&insn->stack_op);
if (ret)
return ret;
@@ -352,7 +360,7 @@ static void add_ignores(struct objtool_file *file)
struct section *sec;
struct symbol *func;
list_for_each_entry(sec, &file->elf->sections, list) {
for_each_sec(file, sec) {
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC)
continue;
@@ -361,7 +369,7 @@ static void add_ignores(struct objtool_file *file)
continue;
func_for_each_insn(file, func, insn)
insn->visited = true;
insn->ignore = true;
}
}
}
@@ -381,8 +389,7 @@ static int add_jump_destinations(struct objtool_file *file)
insn->type != INSN_JUMP_UNCONDITIONAL)
continue;
/* skip ignores */
if (insn->visited)
if (insn->ignore)
continue;
rela = find_rela_by_dest_range(insn->sec, insn->offset,
@@ -519,10 +526,13 @@ static int handle_group_alt(struct objtool_file *file,
}
memset(fake_jump, 0, sizeof(*fake_jump));
INIT_LIST_HEAD(&fake_jump->alts);
clear_insn_state(&fake_jump->state);
fake_jump->sec = special_alt->new_sec;
fake_jump->offset = -1;
fake_jump->type = INSN_JUMP_UNCONDITIONAL;
fake_jump->jump_dest = list_next_entry(last_orig_insn, list);
fake_jump->ignore = true;
if (!special_alt->new_len) {
*new_insn = fake_jump;
@@ -844,7 +854,7 @@ static int add_switch_table_alts(struct objtool_file *file)
if (!file->rodata || !file->rodata->rela)
return 0;
list_for_each_entry(sec, &file->elf->sections, list) {
for_each_sec(file, sec) {
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC)
continue;
@@ -901,21 +911,423 @@ static bool is_fentry_call(struct instruction *insn)
return false;
}
static bool has_modified_stack_frame(struct instruction *insn)
static bool has_modified_stack_frame(struct insn_state *state)
{
return (insn->state & STATE_FP_SAVED) ||
(insn->state & STATE_FP_SETUP);
int i;
if (state->cfa.base != initial_func_cfi.cfa.base ||
state->cfa.offset != initial_func_cfi.cfa.offset ||
state->stack_size != initial_func_cfi.cfa.offset ||
state->drap)
return true;
for (i = 0; i < CFI_NUM_REGS; i++)
if (state->regs[i].base != initial_func_cfi.regs[i].base ||
state->regs[i].offset != initial_func_cfi.regs[i].offset)
return true;
return false;
}
static bool has_valid_stack_frame(struct instruction *insn)
static bool has_valid_stack_frame(struct insn_state *state)
{
return (insn->state & STATE_FP_SAVED) &&
(insn->state & STATE_FP_SETUP);
if (state->cfa.base == CFI_BP && state->regs[CFI_BP].base == CFI_CFA &&
state->regs[CFI_BP].offset == -16)
return true;
if (state->drap && state->regs[CFI_BP].base == CFI_BP)
return true;
return false;
}
static unsigned int frame_state(unsigned long state)
static void save_reg(struct insn_state *state, unsigned char reg, int base,
int offset)
{
return (state & (STATE_FP_SAVED | STATE_FP_SETUP));
if ((arch_callee_saved_reg(reg) ||
(state->drap && reg == state->drap_reg)) &&
state->regs[reg].base == CFI_UNDEFINED) {
state->regs[reg].base = base;
state->regs[reg].offset = offset;
}
}
static void restore_reg(struct insn_state *state, unsigned char reg)
{
state->regs[reg].base = CFI_UNDEFINED;
state->regs[reg].offset = 0;
}
/*
* A note about DRAP stack alignment:
*
* GCC has the concept of a DRAP register, which is used to help keep track of
* the stack pointer when aligning the stack. r10 or r13 is used as the DRAP
* register. The typical DRAP pattern is:
*
* 4c 8d 54 24 08 lea 0x8(%rsp),%r10
* 48 83 e4 c0 and $0xffffffffffffffc0,%rsp
* 41 ff 72 f8 pushq -0x8(%r10)
* 55 push %rbp
* 48 89 e5 mov %rsp,%rbp
* (more pushes)
* 41 52 push %r10
* ...
* 41 5a pop %r10
* (more pops)
* 5d pop %rbp
* 49 8d 62 f8 lea -0x8(%r10),%rsp
* c3 retq
*
* There are some variations in the epilogues, like:
*
* 5b pop %rbx
* 41 5a pop %r10
* 41 5c pop %r12
* 41 5d pop %r13
* 41 5e pop %r14
* c9 leaveq
* 49 8d 62 f8 lea -0x8(%r10),%rsp
* c3 retq
*
* and:
*
* 4c 8b 55 e8 mov -0x18(%rbp),%r10
* 48 8b 5d e0 mov -0x20(%rbp),%rbx
* 4c 8b 65 f0 mov -0x10(%rbp),%r12
* 4c 8b 6d f8 mov -0x8(%rbp),%r13
* c9 leaveq
* 49 8d 62 f8 lea -0x8(%r10),%rsp
* c3 retq
*
* Sometimes r13 is used as the DRAP register, in which case it's saved and
* restored beforehand:
*
* 41 55 push %r13
* 4c 8d 6c 24 10 lea 0x10(%rsp),%r13
* 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
* ...
* 49 8d 65 f0 lea -0x10(%r13),%rsp
* 41 5d pop %r13
* c3 retq
*/
static int update_insn_state(struct instruction *insn, struct insn_state *state)
{
struct stack_op *op = &insn->stack_op;
struct cfi_reg *cfa = &state->cfa;
struct cfi_reg *regs = state->regs;
/* stack operations don't make sense with an undefined CFA */
if (cfa->base == CFI_UNDEFINED) {
if (insn->func) {
WARN_FUNC("undefined stack state", insn->sec, insn->offset);
return -1;
}
return 0;
}
switch (op->dest.type) {
case OP_DEST_REG:
switch (op->src.type) {
case OP_SRC_REG:
if (cfa->base == op->src.reg && cfa->base == CFI_SP &&
op->dest.reg == CFI_BP && regs[CFI_BP].base == CFI_CFA &&
regs[CFI_BP].offset == -cfa->offset) {
/* mov %rsp, %rbp */
cfa->base = op->dest.reg;
state->bp_scratch = false;
} else if (state->drap) {
/* drap: mov %rsp, %rbp */
regs[CFI_BP].base = CFI_BP;
regs[CFI_BP].offset = -state->stack_size;
state->bp_scratch = false;
} else if (!nofp) {
WARN_FUNC("unknown stack-related register move",
insn->sec, insn->offset);
return -1;
}
break;
case OP_SRC_ADD:
if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
/* add imm, %rsp */
state->stack_size -= op->src.offset;
if (cfa->base == CFI_SP)
cfa->offset -= op->src.offset;
break;
}
if (op->dest.reg == CFI_SP && op->src.reg == CFI_BP) {
/* lea disp(%rbp), %rsp */
state->stack_size = -(op->src.offset + regs[CFI_BP].offset);
break;
}
if (op->dest.reg != CFI_BP && op->src.reg == CFI_SP &&
cfa->base == CFI_SP) {
/* drap: lea disp(%rsp), %drap */
state->drap_reg = op->dest.reg;
break;
}
if (state->drap && op->dest.reg == CFI_SP &&
op->src.reg == state->drap_reg) {
/* drap: lea disp(%drap), %rsp */
cfa->base = CFI_SP;
cfa->offset = state->stack_size = -op->src.offset;
state->drap_reg = CFI_UNDEFINED;
state->drap = false;
break;
}
if (op->dest.reg == state->cfa.base) {
WARN_FUNC("unsupported stack register modification",
insn->sec, insn->offset);
return -1;
}
break;
case OP_SRC_AND:
if (op->dest.reg != CFI_SP ||
(state->drap_reg != CFI_UNDEFINED && cfa->base != CFI_SP) ||
(state->drap_reg == CFI_UNDEFINED && cfa->base != CFI_BP)) {
WARN_FUNC("unsupported stack pointer realignment",
insn->sec, insn->offset);
return -1;
}
if (state->drap_reg != CFI_UNDEFINED) {
/* drap: and imm, %rsp */
cfa->base = state->drap_reg;
cfa->offset = state->stack_size = 0;
state->drap = true;
}
/*
* Older versions of GCC (4.8ish) realign the stack
* without DRAP, with a frame pointer.
*/
break;
case OP_SRC_POP:
if (!state->drap && op->dest.type == OP_DEST_REG &&
op->dest.reg == cfa->base) {
/* pop %rbp */
cfa->base = CFI_SP;
}
if (regs[op->dest.reg].offset == -state->stack_size) {
if (state->drap && cfa->base == CFI_BP_INDIRECT &&
op->dest.type == OP_DEST_REG &&
op->dest.reg == state->drap_reg) {
/* drap: pop %drap */
cfa->base = state->drap_reg;
cfa->offset = 0;
}
restore_reg(state, op->dest.reg);
}
state->stack_size -= 8;
if (cfa->base == CFI_SP)
cfa->offset -= 8;
break;
case OP_SRC_REG_INDIRECT:
if (state->drap && op->src.reg == CFI_BP &&
op->src.offset == regs[op->dest.reg].offset) {
/* drap: mov disp(%rbp), %reg */
if (op->dest.reg == state->drap_reg) {
cfa->base = state->drap_reg;
cfa->offset = 0;
}
restore_reg(state, op->dest.reg);
} else if (op->src.reg == cfa->base &&
op->src.offset == regs[op->dest.reg].offset + cfa->offset) {
/* mov disp(%rbp), %reg */
/* mov disp(%rsp), %reg */
restore_reg(state, op->dest.reg);
}
break;
default:
WARN_FUNC("unknown stack-related instruction",
insn->sec, insn->offset);
return -1;
}
break;
case OP_DEST_PUSH:
state->stack_size += 8;
if (cfa->base == CFI_SP)
cfa->offset += 8;
if (op->src.type != OP_SRC_REG)
break;
if (state->drap) {
if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
/* drap: push %drap */
cfa->base = CFI_BP_INDIRECT;
cfa->offset = -state->stack_size;
/* save drap so we know when to undefine it */
save_reg(state, op->src.reg, CFI_CFA, -state->stack_size);
} else if (op->src.reg == CFI_BP && cfa->base == state->drap_reg) {
/* drap: push %rbp */
state->stack_size = 0;
} else if (regs[op->src.reg].base == CFI_UNDEFINED) {
/* drap: push %reg */
save_reg(state, op->src.reg, CFI_BP, -state->stack_size);
}
} else {
/* push %reg */
save_reg(state, op->src.reg, CFI_CFA, -state->stack_size);
}
/* detect when asm code uses rbp as a scratch register */
if (!nofp && insn->func && op->src.reg == CFI_BP &&
cfa->base != CFI_BP)
state->bp_scratch = true;
break;
case OP_DEST_REG_INDIRECT:
if (state->drap) {
if (op->src.reg == cfa->base && op->src.reg == state->drap_reg) {
/* drap: mov %drap, disp(%rbp) */
cfa->base = CFI_BP_INDIRECT;
cfa->offset = op->dest.offset;
/* save drap so we know when to undefine it */
save_reg(state, op->src.reg, CFI_CFA, op->dest.offset);
}
else if (regs[op->src.reg].base == CFI_UNDEFINED) {
/* drap: mov reg, disp(%rbp) */
save_reg(state, op->src.reg, CFI_BP, op->dest.offset);
}
} else if (op->dest.reg == cfa->base) {
/* mov reg, disp(%rbp) */
/* mov reg, disp(%rsp) */
save_reg(state, op->src.reg, CFI_CFA,
op->dest.offset - state->cfa.offset);
}
break;
case OP_DEST_LEAVE:
if ((!state->drap && cfa->base != CFI_BP) ||
(state->drap && cfa->base != state->drap_reg)) {
WARN_FUNC("leave instruction with modified stack frame",
insn->sec, insn->offset);
return -1;
}
/* leave (mov %rbp, %rsp; pop %rbp) */
state->stack_size = -state->regs[CFI_BP].offset - 8;
restore_reg(state, CFI_BP);
if (!state->drap) {
cfa->base = CFI_SP;
cfa->offset -= 8;
}
break;
case OP_DEST_MEM:
if (op->src.type != OP_SRC_POP) {
WARN_FUNC("unknown stack-related memory operation",
insn->sec, insn->offset);
return -1;
}
/* pop mem */
state->stack_size -= 8;
if (cfa->base == CFI_SP)
cfa->offset -= 8;
break;
default:
WARN_FUNC("unknown stack-related instruction",
insn->sec, insn->offset);
return -1;
}
return 0;
}
static bool insn_state_match(struct instruction *insn, struct insn_state *state)
{
struct insn_state *state1 = &insn->state, *state2 = state;
int i;
if (memcmp(&state1->cfa, &state2->cfa, sizeof(state1->cfa))) {
WARN_FUNC("stack state mismatch: cfa1=%d%+d cfa2=%d%+d",
insn->sec, insn->offset,
state1->cfa.base, state1->cfa.offset,
state2->cfa.base, state2->cfa.offset);
} else if (memcmp(&state1->regs, &state2->regs, sizeof(state1->regs))) {
for (i = 0; i < CFI_NUM_REGS; i++) {
if (!memcmp(&state1->regs[i], &state2->regs[i],
sizeof(struct cfi_reg)))
continue;
WARN_FUNC("stack state mismatch: reg1[%d]=%d%+d reg2[%d]=%d%+d",
insn->sec, insn->offset,
i, state1->regs[i].base, state1->regs[i].offset,
i, state2->regs[i].base, state2->regs[i].offset);
break;
}
} else if (state1->drap != state2->drap ||
(state1->drap && state1->drap_reg != state2->drap_reg)) {
WARN_FUNC("stack state mismatch: drap1=%d(%d) drap2=%d(%d)",
insn->sec, insn->offset,
state1->drap, state1->drap_reg,
state2->drap, state2->drap_reg);
} else
return true;
return false;
}
/*
@@ -924,24 +1336,22 @@ static unsigned int frame_state(unsigned long state)
* each instruction and validate all the rules described in
* tools/objtool/Documentation/stack-validation.txt.
*/
static int validate_branch(struct objtool_file *file,
struct instruction *first, unsigned char first_state)
static int validate_branch(struct objtool_file *file, struct instruction *first,
struct insn_state state)
{
struct alternative *alt;
struct instruction *insn;
struct section *sec;
struct symbol *func = NULL;
unsigned char state;
int ret;
insn = first;
sec = insn->sec;
state = first_state;
if (insn->alt_group && list_empty(&insn->alts)) {
WARN_FUNC("don't know how to handle branch to middle of alternative instruction group",
sec, insn->offset);
return 1;
return -1;
}
while (1) {
@@ -951,23 +1361,21 @@ static int validate_branch(struct objtool_file *file,
func->name, insn->func->name);
return 1;
}
func = insn->func;
}
func = insn->func;
if (insn->visited) {
if (frame_state(insn->state) != frame_state(state)) {
WARN_FUNC("frame pointer state mismatch",
sec, insn->offset);
if (!!insn_state_match(insn, &state))
return 1;
}
return 0;
}
insn->visited = true;
insn->state = state;
insn->visited = true;
list_for_each_entry(alt, &insn->alts, list) {
ret = validate_branch(file, alt->insn, state);
if (ret)
@@ -976,50 +1384,24 @@ static int validate_branch(struct objtool_file *file,
switch (insn->type) {
case INSN_FP_SAVE:
if (!nofp) {
if (state & STATE_FP_SAVED) {
WARN_FUNC("duplicate frame pointer save",
sec, insn->offset);
return 1;
}
state |= STATE_FP_SAVED;
}
break;
case INSN_FP_SETUP:
if (!nofp) {
if (state & STATE_FP_SETUP) {
WARN_FUNC("duplicate frame pointer setup",
sec, insn->offset);
return 1;
}
state |= STATE_FP_SETUP;
}
break;
case INSN_FP_RESTORE:
if (!nofp) {
if (has_valid_stack_frame(insn))
state &= ~STATE_FP_SETUP;
state &= ~STATE_FP_SAVED;
}
break;
case INSN_RETURN:
if (!nofp && has_modified_stack_frame(insn)) {
WARN_FUNC("return without frame pointer restore",
if (func && has_modified_stack_frame(&state)) {
WARN_FUNC("return with modified stack frame",
sec, insn->offset);
return 1;
}
if (state.bp_scratch) {
WARN("%s uses BP as a scratch register",
insn->func->name);
return 1;
}
return 0;
case INSN_CALL:
if (is_fentry_call(insn)) {
state |= STATE_FENTRY;
if (is_fentry_call(insn))
break;
}
ret = dead_end_function(file, insn->call_dest);
if (ret == 1)
@@ -1029,7 +1411,7 @@ static int validate_branch(struct objtool_file *file,
/* fallthrough */
case INSN_CALL_DYNAMIC:
if (!nofp && !has_valid_stack_frame(insn)) {
if (!nofp && func && !has_valid_stack_frame(&state)) {
WARN_FUNC("call without frame pointer save/setup",
sec, insn->offset);
return 1;
@@ -1043,8 +1425,8 @@ static int validate_branch(struct objtool_file *file,
state);
if (ret)
return 1;
} else if (has_modified_stack_frame(insn)) {
WARN_FUNC("sibling call from callable instruction with changed frame pointer",
} else if (func && has_modified_stack_frame(&state)) {
WARN_FUNC("sibling call from callable instruction with modified stack frame",
sec, insn->offset);
return 1;
} /* else it's a sibling call */
@@ -1055,15 +1437,29 @@ static int validate_branch(struct objtool_file *file,
break;
case INSN_JUMP_DYNAMIC:
if (list_empty(&insn->alts) &&
has_modified_stack_frame(insn)) {
WARN_FUNC("sibling call from callable instruction with changed frame pointer",
if (func && list_empty(&insn->alts) &&
has_modified_stack_frame(&state)) {
WARN_FUNC("sibling call from callable instruction with modified stack frame",
sec, insn->offset);
return 1;
}
return 0;
case INSN_CONTEXT_SWITCH:
if (func) {
WARN_FUNC("unsupported instruction in callable function",
sec, insn->offset);
return 1;
}
return 0;
case INSN_STACK:
if (update_insn_state(insn, &state))
return -1;
break;
default:
break;
}
@@ -1094,12 +1490,18 @@ static bool is_ubsan_insn(struct instruction *insn)
"__ubsan_handle_builtin_unreachable"));
}
static bool ignore_unreachable_insn(struct symbol *func,
struct instruction *insn)
static bool ignore_unreachable_insn(struct instruction *insn)
{
int i;
if (insn->type == INSN_NOP)
if (insn->ignore || insn->type == INSN_NOP)
return true;
/*
* Ignore any unused exceptions. This can happen when a whitelisted
* function has an exception table entry.
*/
if (!strcmp(insn->sec->name, ".fixup"))
return true;
/*
@@ -1108,6 +1510,8 @@ static bool ignore_unreachable_insn(struct symbol *func,
*
* End the search at 5 instructions to avoid going into the weeds.
*/
if (!insn->func)
return false;
for (i = 0; i < 5; i++) {
if (is_kasan_insn(insn) || is_ubsan_insn(insn))
@@ -1118,7 +1522,7 @@ static bool ignore_unreachable_insn(struct symbol *func,
continue;
}
if (insn->offset + insn->len >= func->offset + func->len)
if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
break;
insn = list_next_entry(insn, list);
}
@@ -1131,73 +1535,58 @@ static int validate_functions(struct objtool_file *file)
struct section *sec;
struct symbol *func;
struct instruction *insn;
struct insn_state state;
int ret, warnings = 0;
list_for_each_entry(sec, &file->elf->sections, list) {
clear_insn_state(&state);
state.cfa = initial_func_cfi.cfa;
memcpy(&state.regs, &initial_func_cfi.regs,
CFI_NUM_REGS * sizeof(struct cfi_reg));
state.stack_size = initial_func_cfi.cfa.offset;
for_each_sec(file, sec) {
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC)
continue;
insn = find_insn(file, sec, func->offset);
if (!insn)
if (!insn || insn->ignore)
continue;
ret = validate_branch(file, insn, 0);
ret = validate_branch(file, insn, state);
warnings += ret;
}
}
list_for_each_entry(sec, &file->elf->sections, list) {
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC)
continue;
func_for_each_insn(file, func, insn) {
if (insn->visited)
continue;
insn->visited = true;
if (file->ignore_unreachables || warnings ||
ignore_unreachable_insn(func, insn))
continue;
/*
* gcov produces a lot of unreachable
* instructions. If we get an unreachable
* warning and the file has gcov enabled, just
* ignore it, and all other such warnings for
* the file.
*/
if (!file->ignore_unreachables &&
gcov_enabled(file)) {
file->ignore_unreachables = true;
continue;
}
WARN_FUNC("function has unreachable instruction", insn->sec, insn->offset);
warnings++;
}
}
}
return warnings;
}
static int validate_uncallable_instructions(struct objtool_file *file)
static int validate_reachable_instructions(struct objtool_file *file)
{
struct instruction *insn;
int warnings = 0;
if (file->ignore_unreachables)
return 0;
for_each_insn(file, insn) {
if (!insn->visited && insn->type == INSN_RETURN) {
WARN_FUNC("return instruction outside of a callable function",
insn->sec, insn->offset);
warnings++;
}
if (insn->visited || ignore_unreachable_insn(insn))
continue;
/*
* gcov produces a lot of unreachable instructions. If we get
* an unreachable warning and the file has gcov enabled, just
* ignore it, and all other such warnings for the file. Do
* this here because this is an expensive function.
*/
if (gcov_enabled(file))
return 0;
WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
return 1;
}
return warnings;
return 0;
}
static void cleanup(struct objtool_file *file)
@@ -1226,10 +1615,8 @@ int check(const char *_objname, bool _nofp)
nofp = _nofp;
file.elf = elf_open(objname);
if (!file.elf) {
fprintf(stderr, "error reading elf file %s\n", objname);
if (!file.elf)
return 1;
}
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
@@ -1238,20 +1625,27 @@ int check(const char *_objname, bool _nofp)
file.ignore_unreachables = false;
file.c_file = find_section_by_name(file.elf, ".comment");
arch_initial_func_cfi_state(&initial_func_cfi);
ret = decode_sections(&file);
if (ret < 0)
goto out;
warnings += ret;
if (list_empty(&file.insn_list))
goto out;
ret = validate_functions(&file);
if (ret < 0)
goto out;
warnings += ret;
ret = validate_uncallable_instructions(&file);
if (ret < 0)
goto out;
warnings += ret;
if (!warnings) {
ret = validate_reachable_instructions(&file);
if (ret < 0)
goto out;
warnings += ret;
}
out:
cleanup(&file);