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objtool: Add ORC unwind table generation

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Now that objtool knows the states of all registers on the stack for each
instruction, it's straightforward to generate debuginfo for an unwinder
to use.

Instead of generating DWARF, generate a new format called ORC, which is
more suitable for an in-kernel unwinder.  See
Documentation/x86/orc-unwinder.txt for a more detailed description of
this new debuginfo format and why it's preferable to DWARF.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/c9b9f01ba6c5ed2bdc9bb0957b78167fdbf9632e.1499786555.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf
2017-07-11 10:33:42 -05:00
committed by Ingo Molnar
parent 5a3cf86978
commit 627fce1480
14 changed files with 916 additions and 60 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
tools/objtool/check.c
View File

@@ -36,8 +36,8 @@ 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)
struct instruction *find_insn(struct objtool_file *file,
struct section *sec, unsigned long offset)
{
struct instruction *insn;
@@ -259,6 +259,11 @@ static int decode_instructions(struct objtool_file *file)
if (!(sec->sh.sh_flags & SHF_EXECINSTR))
continue;
if (strcmp(sec->name, ".altinstr_replacement") &&
strcmp(sec->name, ".altinstr_aux") &&
strncmp(sec->name, ".discard.", 9))
sec->text = true;
for (offset = 0; offset < sec->len; offset += insn->len) {
insn = malloc(sizeof(*insn));
if (!insn) {
@@ -947,6 +952,30 @@ static bool has_valid_stack_frame(struct insn_state *state)
return false;
}
static int update_insn_state_regs(struct instruction *insn, struct insn_state *state)
{
struct cfi_reg *cfa = &state->cfa;
struct stack_op *op = &insn->stack_op;
if (cfa->base != CFI_SP)
return 0;
/* push */
if (op->dest.type == OP_DEST_PUSH)
cfa->offset += 8;
/* pop */
if (op->src.type == OP_SRC_POP)
cfa->offset -= 8;
/* add immediate to sp */
if (op->dest.type == OP_DEST_REG && op->src.type == OP_SRC_ADD &&
op->dest.reg == CFI_SP && op->src.reg == CFI_SP)
cfa->offset -= op->src.offset;
return 0;
}
static void save_reg(struct insn_state *state, unsigned char reg, int base,
int offset)
{
@@ -1032,6 +1061,9 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
return 0;
}
if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET)
return update_insn_state_regs(insn, state);
switch (op->dest.type) {
case OP_DEST_REG:
@@ -1323,6 +1355,10 @@ static bool insn_state_match(struct instruction *insn, struct insn_state *state)
break;
}
} else if (state1->type != state2->type) {
WARN_FUNC("stack state mismatch: type1=%d type2=%d",
insn->sec, insn->offset, state1->type, state2->type);
} 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)",
@@ -1613,7 +1649,7 @@ static void cleanup(struct objtool_file *file)
elf_close(file->elf);
}
int check(const char *_objname, bool _nofp)
int check(const char *_objname, bool _nofp, bool orc)
{
struct objtool_file file;
int ret, warnings = 0;
@@ -1621,7 +1657,7 @@ int check(const char *_objname, bool _nofp)
objname = _objname;
nofp = _nofp;
file.elf = elf_open(objname);
file.elf = elf_open(objname, orc ? O_RDWR : O_RDONLY);
if (!file.elf)
return 1;
@@ -1654,6 +1690,20 @@ int check(const char *_objname, bool _nofp)
warnings += ret;
}
if (orc) {
ret = create_orc(&file);
if (ret < 0)
goto out;
ret = create_orc_sections(&file);
if (ret < 0)
goto out;
ret = elf_write(file.elf);
if (ret < 0)
goto out;
}
out:
cleanup(&file);