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Subject[RFC V3 01/18] objtool: Add abstraction for computation of symbols offsets
Date
The jump destination and relocation offset used previously are only
reliable on x86_64 architecture. We abstract these computations by calling
arch-dependent implementations.

Signed-off-by: Raphael Gault <raphael.gault@arm.com>
---
tools/objtool/arch.h | 6 ++++++
tools/objtool/arch/x86/decode.c | 11 +++++++++++
tools/objtool/check.c | 15 ++++++++++-----
3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h
index 580e344db3dd..2a38a834cf40 100644
--- a/tools/objtool/arch.h
+++ b/tools/objtool/arch.h
@@ -64,6 +64,8 @@ struct stack_op {
struct op_src src;
};

+struct instruction;
+
void arch_initial_func_cfi_state(struct cfi_state *state);

int arch_decode_instruction(struct elf *elf, struct section *sec,
@@ -73,4 +75,8 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,

bool arch_callee_saved_reg(unsigned char reg);

+unsigned long arch_jump_destination(struct instruction *insn);
+
+unsigned long arch_dest_rela_offset(int addend);
+
#endif /* _ARCH_H */
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 584568f27a83..8767ee935c47 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -11,6 +11,7 @@
#include "lib/inat.c"
#include "lib/insn.c"

+#include "../../check.h"
#include "../../elf.h"
#include "../../arch.h"
#include "../../warn.h"
@@ -66,6 +67,11 @@ bool arch_callee_saved_reg(unsigned char reg)
}
}

+unsigned long arch_dest_rela_offset(int addend)
+{
+ return addend + 4;
+}
+
int arch_decode_instruction(struct elf *elf, struct section *sec,
unsigned long offset, unsigned int maxlen,
unsigned int *len, unsigned char *type,
@@ -497,3 +503,8 @@ void arch_initial_func_cfi_state(struct cfi_state *state)
state->regs[16].base = CFI_CFA;
state->regs[16].offset = -8;
}
+
+unsigned long arch_jump_destination(struct instruction *insn)
+{
+ return insn->offset + insn->len + insn->immediate;
+}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 172f99195726..b37ca4822f25 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -565,7 +565,7 @@ static int add_jump_destinations(struct objtool_file *file)
insn->len);
if (!rela) {
dest_sec = insn->sec;
- dest_off = insn->offset + insn->len + insn->immediate;
+ dest_off = arch_jump_destination(insn);
} else if (rela->sym->type == STT_SECTION) {
dest_sec = rela->sym->sec;
dest_off = rela->addend + 4;
@@ -659,7 +659,7 @@ static int add_call_destinations(struct objtool_file *file)
rela = find_rela_by_dest_range(insn->sec, insn->offset,
insn->len);
if (!rela) {
- dest_off = insn->offset + insn->len + insn->immediate;
+ dest_off = arch_jump_destination(insn);
insn->call_dest = find_symbol_by_offset(insn->sec,
dest_off);

@@ -672,14 +672,19 @@ static int add_call_destinations(struct objtool_file *file)
}

} else if (rela->sym->type == STT_SECTION) {
+ /*
+ * the original x86_64 code adds 4 to the rela->addend
+ * which is not needed on arm64 architecture.
+ */
+ dest_off = arch_dest_rela_offset(rela->addend);
insn->call_dest = find_symbol_by_offset(rela->sym->sec,
- rela->addend+4);
+ dest_off);
if (!insn->call_dest ||
insn->call_dest->type != STT_FUNC) {
- WARN_FUNC("can't find call dest symbol at %s+0x%x",
+ WARN_FUNC("can't find call dest symbol at %s+0x%lx",
insn->sec, insn->offset,
rela->sym->sec->name,
- rela->addend + 4);
+ dest_off);
return -1;
}
} else
--
2.17.1
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