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Message-ID: <20220622154920.95075-8-chenzhongjin@huawei.com>
Date: Wed, 22 Jun 2022 23:48:54 +0800
From: Chen Zhongjin <chenzhongjin@...wei.com>
To: <linux-kernel@...r.kernel.org>, <linux-arch@...r.kernel.org>,
<linuxppc-dev@...ts.ozlabs.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kbuild@...r.kernel.org>, <live-patching@...r.kernel.org>
CC: <jpoimboe@...nel.org>, <peterz@...radead.org>,
<catalin.marinas@....com>, <will@...nel.org>,
<masahiroy@...nel.org>, <michal.lkml@...kovi.net>,
<ndesaulniers@...gle.com>, <mark.rutland@....com>,
<pasha.tatashin@...een.com>, <broonie@...nel.org>,
<chenzhongjin@...wei.com>, <rmk+kernel@...linux.org.uk>,
<madvenka@...ux.microsoft.com>, <christophe.leroy@...roup.eu>
Subject: [PATCH v5 07/33] objtool: arm64: Decode LDR instructions
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@...hat.com>
Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
---
tools/objtool/arch/arm64/decode.c | 87 +++++++++++++++++++++++++++-
tools/objtool/arch/x86/decode.c | 5 ++
tools/objtool/check.c | 3 +
tools/objtool/include/objtool/arch.h | 2 +
4 files changed, 96 insertions(+), 1 deletion(-)
diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c
index c8d50d041889..9bdd59e0d11d 100644
--- a/tools/objtool/arch/arm64/decode.c
+++ b/tools/objtool/arch/arm64/decode.c
@@ -31,6 +31,64 @@ 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;
+};
+
+DEFINE_HASHTABLE(invalid_insns, 16);
+
+static int record_invalid_insn(const struct section *sec,
+ unsigned long offset)
+{
+ 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);
+ return 0;
+ }
+
+ loc = malloc(sizeof(*loc));
+ if (!loc) {
+ WARN("malloc failed");
+ return -1;
+ }
+
+ loc->sec = sec;
+ loc->offset = offset;
+
+ 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) {
+ list_del(&insn->list);
+ hash_del(&insn->hash);
+ free(insn);
+ }
+
+ hash_del(&loc->hnode);
+ free(loc);
+ }
+
+ return res;
+}
+
bool arch_callee_saved_reg(unsigned char reg)
{
switch (reg) {
@@ -351,7 +409,34 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec
break;
case AARCH64_INSN_CLS_LDST:
{
- return decode_load_store(insn, immediate, ops_list);
+ int ret;
+
+ ret = decode_load_store(insn, immediate, ops_list);
+ if (ret <= 0)
+ return ret;
+
+ /*
+ * For LDR ops, assembler can generate the data to be
+ * loaded in the code section
+ * Record and remove these data because they
+ * are never excuted
+ */
+ 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;
+
+ ret = record_invalid_insn(sec, offset + pc_offset);
+
+ /* 64-bit literal */
+ if (insn & BIT(30))
+ ret = record_invalid_insn(sec, offset + pc_offset + 4);
+
+ return ret;
+ }
break;
}
default:
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 8b990a52aada..081b5e72f8df 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -693,6 +693,11 @@ int arch_decode_instruction(struct objtool_file *file, 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 35d0a1bc4279..c0feb6db7c6d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -439,6 +439,9 @@ static int decode_instructions(struct objtool_file *file)
if (opts.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 9b19cc304195..651262af2655 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -77,6 +77,8 @@ int arch_decode_instruction(struct objtool_file *file, 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);
--
2.17.1
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