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objtool: Refactor ORC section generation
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Decouple ORC entries from instructions.  This simplifies the
control/data flow, and is going to make it easier to support alternative
instructions which change the stack layout.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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Josh Poimboeuf committed Jan 14, 2021
1 parent 5ed934e commit ab4e074
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Showing 7 changed files with 140 additions and 159 deletions.
4 changes: 0 additions & 4 deletions tools/objtool/Makefile
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Expand Up @@ -47,10 +47,6 @@ ifeq ($(SRCARCH),x86)
SUBCMD_ORC := y
endif

ifeq ($(SUBCMD_ORC),y)
CFLAGS += -DINSN_USE_ORC
endif

export SUBCMD_CHECK SUBCMD_ORC
export srctree OUTPUT CFLAGS SRCARCH AWK
include $(srctree)/tools/build/Makefile.include
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6 changes: 1 addition & 5 deletions tools/objtool/builtin-orc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -51,11 +51,7 @@ int cmd_orc(int argc, const char **argv)
if (list_empty(&file->insn_list))
return 0;

ret = create_orc(file);
if (ret)
return ret;

ret = create_orc_sections(file);
ret = orc_create(file);
if (ret)
return ret;

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4 changes: 0 additions & 4 deletions tools/objtool/include/objtool/arch.h
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Expand Up @@ -11,10 +11,6 @@
#include <objtool/objtool.h>
#include <objtool/cfi.h>

#ifdef INSN_USE_ORC
#include <asm/orc_types.h>
#endif

enum insn_type {
INSN_JUMP_CONDITIONAL,
INSN_JUMP_UNCONDITIONAL,
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3 changes: 0 additions & 3 deletions tools/objtool/include/objtool/check.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,9 +43,6 @@ struct instruction {
struct symbol *func;
struct list_head stack_ops;
struct cfi_state cfi;
#ifdef INSN_USE_ORC
struct orc_entry orc;
#endif
};

static inline bool is_static_jump(struct instruction *insn)
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3 changes: 1 addition & 2 deletions tools/objtool/include/objtool/objtool.h
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Expand Up @@ -26,7 +26,6 @@ struct objtool_file *objtool_open_read(const char *_objname);

int check(struct objtool_file *file);
int orc_dump(const char *objname);
int create_orc(struct objtool_file *file);
int create_orc_sections(struct objtool_file *file);
int orc_create(struct objtool_file *file);

#endif /* _OBJTOOL_H */
272 changes: 137 additions & 135 deletions tools/objtool/orc_gen.c
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Expand Up @@ -13,89 +13,84 @@
#include <objtool/warn.h>
#include <objtool/endianness.h>

int create_orc(struct objtool_file *file)
static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi)
{
struct instruction *insn;
struct instruction *insn = container_of(cfi, struct instruction, cfi);
struct cfi_reg *bp = &cfi->regs[CFI_BP];

for_each_insn(file, insn) {
struct orc_entry *orc = &insn->orc;
struct cfi_reg *cfa = &insn->cfi.cfa;
struct cfi_reg *bp = &insn->cfi.regs[CFI_BP];
memset(orc, 0, sizeof(*orc));

if (!insn->sec->text)
continue;

orc->end = insn->cfi.end;
orc->end = cfi->end;

if (cfa->base == CFI_UNDEFINED) {
orc->sp_reg = ORC_REG_UNDEFINED;
continue;
}

switch (cfa->base) {
case CFI_SP:
orc->sp_reg = ORC_REG_SP;
break;
case CFI_SP_INDIRECT:
orc->sp_reg = ORC_REG_SP_INDIRECT;
break;
case CFI_BP:
orc->sp_reg = ORC_REG_BP;
break;
case CFI_BP_INDIRECT:
orc->sp_reg = ORC_REG_BP_INDIRECT;
break;
case CFI_R10:
orc->sp_reg = ORC_REG_R10;
break;
case CFI_R13:
orc->sp_reg = ORC_REG_R13;
break;
case CFI_DI:
orc->sp_reg = ORC_REG_DI;
break;
case CFI_DX:
orc->sp_reg = ORC_REG_DX;
break;
default:
WARN_FUNC("unknown CFA base reg %d",
insn->sec, insn->offset, cfa->base);
return -1;
}
if (cfi->cfa.base == CFI_UNDEFINED) {
orc->sp_reg = ORC_REG_UNDEFINED;
return 0;
}

switch(bp->base) {
case CFI_UNDEFINED:
orc->bp_reg = ORC_REG_UNDEFINED;
break;
case CFI_CFA:
orc->bp_reg = ORC_REG_PREV_SP;
break;
case CFI_BP:
orc->bp_reg = ORC_REG_BP;
break;
default:
WARN_FUNC("unknown BP base reg %d",
insn->sec, insn->offset, bp->base);
return -1;
}
switch (cfi->cfa.base) {
case CFI_SP:
orc->sp_reg = ORC_REG_SP;
break;
case CFI_SP_INDIRECT:
orc->sp_reg = ORC_REG_SP_INDIRECT;
break;
case CFI_BP:
orc->sp_reg = ORC_REG_BP;
break;
case CFI_BP_INDIRECT:
orc->sp_reg = ORC_REG_BP_INDIRECT;
break;
case CFI_R10:
orc->sp_reg = ORC_REG_R10;
break;
case CFI_R13:
orc->sp_reg = ORC_REG_R13;
break;
case CFI_DI:
orc->sp_reg = ORC_REG_DI;
break;
case CFI_DX:
orc->sp_reg = ORC_REG_DX;
break;
default:
WARN_FUNC("unknown CFA base reg %d",
insn->sec, insn->offset, cfi->cfa.base);
return -1;
}

orc->sp_offset = cfa->offset;
orc->bp_offset = bp->offset;
orc->type = insn->cfi.type;
switch (bp->base) {
case CFI_UNDEFINED:
orc->bp_reg = ORC_REG_UNDEFINED;
break;
case CFI_CFA:
orc->bp_reg = ORC_REG_PREV_SP;
break;
case CFI_BP:
orc->bp_reg = ORC_REG_BP;
break;
default:
WARN_FUNC("unknown BP base reg %d",
insn->sec, insn->offset, bp->base);
return -1;
}

orc->sp_offset = cfi->cfa.offset;
orc->bp_offset = bp->offset;
orc->type = cfi->type;

return 0;
}

static int create_orc_entry(struct elf *elf, struct section *u_sec, struct section *ip_relocsec,
unsigned int idx, struct section *insn_sec,
unsigned long insn_off, struct orc_entry *o)
static int write_orc_entry(struct elf *elf, struct section *orc_sec,
struct section *ip_rsec, unsigned int idx,
struct section *insn_sec, unsigned long insn_off,
struct orc_entry *o)
{
struct orc_entry *orc;
struct reloc *reloc;

/* populate ORC data */
orc = (struct orc_entry *)u_sec->data->d_buf + idx;
orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
memcpy(orc, o, sizeof(*orc));
orc->sp_offset = bswap_if_needed(orc->sp_offset);
orc->bp_offset = bswap_if_needed(orc->bp_offset);
Expand All @@ -117,102 +112,109 @@ static int create_orc_entry(struct elf *elf, struct section *u_sec, struct secti

reloc->type = R_X86_64_PC32;
reloc->offset = idx * sizeof(int);
reloc->sec = ip_relocsec;
reloc->sec = ip_rsec;

elf_add_reloc(elf, reloc);

return 0;
}

int create_orc_sections(struct objtool_file *file)
struct orc_list_entry {
struct list_head list;
struct orc_entry orc;
struct section *insn_sec;
unsigned long insn_off;
};

static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
struct section *sec, unsigned long offset)
{
struct orc_list_entry *entry = malloc(sizeof(*entry));

if (!entry) {
WARN("malloc failed");
return -1;
}

entry->orc = *orc;
entry->insn_sec = sec;
entry->insn_off = offset;

list_add_tail(&entry->list, orc_list);
return 0;
}

int orc_create(struct objtool_file *file)
{
struct instruction *insn, *prev_insn;
struct section *sec, *u_sec, *ip_relocsec;
unsigned int idx;
struct section *sec, *ip_rsec, *orc_sec;
unsigned int nr = 0, idx = 0;
struct orc_list_entry *entry;
struct list_head orc_list;

struct orc_entry empty = {
.sp_reg = ORC_REG_UNDEFINED,
struct orc_entry null = {
.sp_reg = ORC_REG_UNDEFINED,
.bp_reg = ORC_REG_UNDEFINED,
.type = UNWIND_HINT_TYPE_CALL,
};

sec = find_section_by_name(file->elf, ".orc_unwind");
if (sec) {
WARN("file already has .orc_unwind section, skipping");
return -1;
}

/* count the number of needed orcs */
idx = 0;
/* Build a deduplicated list of ORC entries: */
INIT_LIST_HEAD(&orc_list);
for_each_sec(file, sec) {
struct orc_entry orc, prev_orc = {0};
struct instruction *insn;
bool empty = true;

if (!sec->text)
continue;

prev_insn = NULL;
sec_for_each_insn(file, sec, insn) {
if (!prev_insn ||
memcmp(&insn->orc, &prev_insn->orc,
sizeof(struct orc_entry))) {
idx++;
}
prev_insn = insn;
if (init_orc_entry(&orc, &insn->cfi))
return -1;
if (!memcmp(&prev_orc, &orc, sizeof(orc)))
continue;
if (orc_list_add(&orc_list, &orc, sec, insn->offset))
return -1;
nr++;
prev_orc = orc;
empty = false;
}

/* section terminator */
if (prev_insn)
idx++;
/* Add a section terminator */
if (!empty) {
orc_list_add(&orc_list, &null, sec, sec->len);
nr++;
}
}
if (!idx)
return -1;
if (!nr)
return 0;

/* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
sec = find_section_by_name(file->elf, ".orc_unwind");
if (sec) {
WARN("file already has .orc_unwind section, skipping");
return -1;
}
orc_sec = elf_create_section(file->elf, ".orc_unwind", 0,
sizeof(struct orc_entry), nr);
if (!orc_sec)
return -1;

/* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), idx);
sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr);
if (!sec)
return -1;

ip_relocsec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
if (!ip_relocsec)
ip_rsec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
if (!ip_rsec)
return -1;

/* create .orc_unwind section */
u_sec = elf_create_section(file->elf, ".orc_unwind", 0,
sizeof(struct orc_entry), idx);

/* populate sections */
idx = 0;
for_each_sec(file, sec) {
if (!sec->text)
continue;

prev_insn = NULL;
sec_for_each_insn(file, sec, insn) {
if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
sizeof(struct orc_entry))) {

if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx,
insn->sec, insn->offset,
&insn->orc))
return -1;

idx++;
}
prev_insn = insn;
}

/* section terminator */
if (prev_insn) {
if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx,
prev_insn->sec,
prev_insn->offset + prev_insn->len,
&empty))
return -1;

idx++;
}
/* Write ORC entries to sections: */
list_for_each_entry(entry, &orc_list, list) {
if (write_orc_entry(file->elf, orc_sec, ip_rsec, idx++,
entry->insn_sec, entry->insn_off,
&entry->orc))
return -1;
}

if (elf_rebuild_reloc_section(file->elf, ip_relocsec))
if (elf_rebuild_reloc_section(file->elf, ip_rsec))
return -1;

return 0;
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7 changes: 1 addition & 6 deletions tools/objtool/weak.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,12 +25,7 @@ int __weak orc_dump(const char *_objname)
UNSUPPORTED("orc");
}

int __weak create_orc(struct objtool_file *file)
{
UNSUPPORTED("orc");
}

int __weak create_orc_sections(struct objtool_file *file)
int __weak orc_create(struct objtool_file *file)
{
UNSUPPORTED("orc");
}

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