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Subject[RFC PATCH 09/17] objtool: arm64: Decode LDR instructions
Date
Load literal instructions can generate constants inside code sections.
Record the locations of the constants in order to be able to remove
their corresponding "struct instruction".

Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
tools/objtool/arch/arm64/decode.c | 86 ++++++++++++++++++++++++++++
tools/objtool/arch/x86/decode.c | 5 ++
tools/objtool/check.c | 3 +
tools/objtool/include/objtool/arch.h | 3 +
4 files changed, 97 insertions(+)

diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c
index 1087ede67bcd..b4d4d5b051b0 100644
--- a/tools/objtool/arch/arm64/decode.c
+++ b/tools/objtool/arch/arm64/decode.c
@@ -30,6 +30,73 @@ static unsigned long sign_extend(unsigned long x, int nbits)
return ((~0UL + (sign_bit ^ 1)) << nbits) | x;
}

+struct insn_loc {
+ const struct section *sec;
+ unsigned long offset;
+ struct hlist_node hnode;
+ bool ignorable;
+};
+
+DEFINE_HASHTABLE(invalid_insns, 16);
+
+static int record_invalid_insn(const struct section *sec,
+ unsigned long offset,
+ bool ignore)
+{
+ struct insn_loc *loc;
+ struct hlist_head *l;
+
+ l = &invalid_insns[hash_min(offset, HASH_BITS(invalid_insns))];
+ if (!hlist_empty(l)) {
+ loc = hlist_entry(l->first, struct insn_loc, hnode);
+ loc->ignorable |= ignore;
+ return 0;
+ }
+
+ loc = malloc(sizeof(*loc));
+ if (!loc) {
+ WARN("malloc failed");
+ return -1;
+ }
+
+ loc->sec = sec;
+ loc->offset = offset;
+ loc->ignorable = ignore;
+
+ hash_add(invalid_insns, &loc->hnode, loc->offset);
+
+ return 0;
+}
+
+int arch_post_process_instructions(struct objtool_file *file)
+{
+ struct hlist_node *tmp;
+ struct insn_loc *loc;
+ unsigned int bkt;
+ int res = 0;
+
+ hash_for_each_safe(invalid_insns, bkt, tmp, loc, hnode) {
+ struct instruction *insn;
+
+ insn = find_insn(file, (struct section *) loc->sec, loc->offset);
+ if (insn) {
+ if (loc->ignorable) {
+ list_del(&insn->list);
+ hash_del(&insn->hash);
+ free(insn);
+ } else {
+ WARN_FUNC("can't decode instruction", insn->sec, insn->offset);
+ return -1;
+ }
+ }
+
+ hash_del(&loc->hnode);
+ free(loc);
+ }
+
+ return res;
+}
+
bool arch_callee_saved_reg(unsigned char reg)
{
switch (reg) {
@@ -359,6 +426,25 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
case AARCH64_INSN_CLS_LDST:
if (arm_decode_load_store(insn, type, immediate, ops_list))
break;
+ if (aarch64_insn_is_ldr_lit(insn)) {
+ long pc_offset;
+
+ pc_offset = insn & GENMASK(23, 5);
+ /* Sign extend and multiply by 4 */
+ pc_offset = (pc_offset << (64 - 23));
+ pc_offset = ((pc_offset >> (64 - 23)) >> 5) << 2;
+
+ if (record_invalid_insn(sec, offset + pc_offset, true))
+ return -1;
+
+ /* 64-bit literal */
+ if (insn & BIT(30)) {
+ if (record_invalid_insn(sec,
+ offset + pc_offset + 4,
+ true))
+ return -1;
+ }
+ }
*type = INSN_OTHER;
break;
default:
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 6baa22732ca6..e76d987ce3c7 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -549,6 +549,11 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
return 0;
}

+int arch_post_process_instructions(struct objtool_file *file)
+{
+ return 0;
+}
+
void arch_initial_func_cfi_state(struct cfi_init_state *state)
{
int i;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 270b507e7098..d902697a388e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -319,6 +319,9 @@ static int decode_instructions(struct objtool_file *file)
if (stats)
printf("nr_insns: %lu\n", nr_insns);

+ if (arch_post_process_instructions(file))
+ return -1;
+
return 0;

err:
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index 6ff0685f5cc5..456d0465b676 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -66,6 +66,7 @@ struct stack_op {
struct list_head list;
};

+struct objtool_file;
struct instruction;

void arch_initial_func_cfi_state(struct cfi_init_state *state);
@@ -76,6 +77,8 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
unsigned long *immediate,
struct list_head *ops_list);

+int arch_post_process_instructions(struct objtool_file *file);
+
bool arch_callee_saved_reg(unsigned char reg);

unsigned long arch_jump_destination(struct instruction *insn);
--
2.25.4
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