[PATCH 1/3] objtool: Refactor ORC section generation

From: Josh Poimboeuf
Date: Wed Dec 23 2020 - 00:20:55 EST

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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@xxxxxxxxxx>
---
tools/objtool/Makefile | 4 -
tools/objtool/arch.h | 4 -
tools/objtool/builtin-orc.c | 6 +-
tools/objtool/check.h | 3 -
tools/objtool/objtool.h | 3 +-
tools/objtool/orc_gen.c | 272 ++++++++++++++++++------------------
tools/objtool/weak.c | 7 +-
7 files changed, 140 insertions(+), 159 deletions(-)

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 5cdb19036d7f..a43096f713c7 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -46,10 +46,6 @@ 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
diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h
index 4a84c3081b8e..5e3f3ea8bb89 100644
--- a/tools/objtool/arch.h
+++ b/tools/objtool/arch.h
@@ -11,10 +11,6 @@
#include "objtool.h"
#include "cfi.h"

-#ifdef INSN_USE_ORC
-#include <asm/orc_types.h>
-#endif
-
enum insn_type {
INSN_JUMP_CONDITIONAL,
INSN_JUMP_UNCONDITIONAL,
diff --git a/tools/objtool/builtin-orc.c b/tools/objtool/builtin-orc.c
index 7b31121fa60b..508bdf6ae8dc 100644
--- a/tools/objtool/builtin-orc.c
+++ b/tools/objtool/builtin-orc.c
@@ -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;

diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index 5ec00a4b891b..4c10916ff1cf 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -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)
diff --git a/tools/objtool/objtool.h b/tools/objtool/objtool.h
index 4125d4578b23..5e58d3537e2f 100644
--- a/tools/objtool/objtool.h
+++ b/tools/objtool/objtool.h
@@ -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 */
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 235663b96adc..73efba2bfa72 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -12,89 +12,84 @@
#include "check.h"
#include "warn.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));

/* populate reloc for ip */
@@ -133,102 +128,109 @@ 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;
diff --git a/tools/objtool/weak.c b/tools/objtool/weak.c
index 7843e9a7a72f..553ec9ce51ba 100644
--- a/tools/objtool/weak.c
+++ b/tools/objtool/weak.c
@@ -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");
}
--
2.29.2

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