On Thu, Jan 18, 2018 at 02:48:18PM +0100, Peter Zijlstra wrote:
> @@ -1216,7 +1218,8 @@ static bool __grow_static_block(struct o
>
> switch (insn->type) {
> case INSN_JUMP_UNCONDITIONAL:
> - /* mark this instruction, terminate this section */
> + /* follow the jump, mark this instruction, terminate this
> section */
> + jmp_grow_static_block(file, insn->jump_dest);
Hmm we should only do this when the jump is backwards, if its forwards
we should just mark the destination instruction and let the main
iteration loop take it.
> insn->static_jump_dest = true;
> return false;
>
something like the below merged in maybe; I'm going to look at this
again later, my brain is completely useless today :/
Josh, how would you feel about adding the bits required to make objtool
a full disassembler? That would make it far easier to visualse the state
and I don't think its _that_ much more, all the difficult bits are
already done afaict, all we need is infrastructure to print the already
fully decoded instruction.
---
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1210,16 +1210,16 @@ static int read_retpoline_hints(struct o
static void jmp_grow_static_block(struct objtool_file *file, struct
instruction *insn);
static bool __grow_static_block(struct objtool_file *file,
- struct instruction *insn, bool ign_bt)
+ struct instruction *insn)
{
- /* if a jump can come in here, terminate */
- if (insn->branch_target && !ign_bt)
+ /* if a !static jump can come in here, terminate */
+ if (insn->branch_target && !insn->static_jump_dest)
return false;
switch (insn->type) {
case INSN_JUMP_UNCONDITIONAL:
/* follow the jump, mark this instruction, terminate this
section */
- jmp_grow_static_block(file, insn->jump_dest);
+ jmp_grow_static_block(file, insn);
insn->static_jump_dest = true;
return false;
@@ -1243,27 +1243,43 @@ static bool __grow_static_block(struct o
static void jmp_grow_static_block(struct objtool_file *file, struct
instruction *insn)
{
- bool ignore = true;
+ struct instruction *dest = insn->jump_dest;
+ bool static_block = true;
- /* !jump_dest */
- if (!insn)
+ if (!dest)
return;
/* more than a single site jumps here, can't be certain */
- if (insn->branch_target > 1)
+ if (dest->branch_target > 1)
return;
- for (; &insn->list != &file->insn_list;
- insn = list_next_entry(insn, list)) {
-
+ if (dest->offset > insn->offset) {
/*
- * Per definition the first insn of a jump is a branch target,
- * don't terminate because of that.
+ * fwd jump, the main iteration will still get there.
+ * make sure it continues the section there.
*/
- if (!__grow_static_block(file, insn, ignore))
- break;
+ dest->static_jump_dest = true;
+ return;
+ }
- ignore = false;
+ /* backwards jump, we need to revisit the instructions */
+ for (; static_block && dest != insn; dest = list_next_entry(dest,
list)) {
+
+ static_block = __grow_static_block(file, dest);
+
+ if (insn->type == INSN_CALL) {
+ struct symbol *func = insn->call_dest;
+ if (!func)
+ continue;
+
+ /*
+ * we flipped the call to static, update the stats.
+ */
+ if (insn->static_jump_dest) {
+ func->non_static_call--;
+ func->static_call++;
+ }
+ }
}
}
@@ -1276,7 +1292,7 @@ static int grow_static_blocks(struct obj
for_each_insn(file, insn) {
if (static_block || insn->static_jump_dest)
- static_block = __grow_static_block(file, insn,
!static_block);
+ static_block = __grow_static_block(file, insn);
if (insn->type == INSN_CALL) {
func = insn->call_dest;
@@ -1284,9 +1300,9 @@ static int grow_static_blocks(struct obj
continue;
if (static_block)
- func->static_call = true;
+ func->static_call++;
else
- func->non_static_call = true;
+ func->non_static_call++;
}
}
@@ -1301,7 +1317,7 @@ static int grow_static_blocks(struct obj
/* static && !non_static -- only static callers */
func_for_each_insn(file, func, insn) {
- if (!__grow_static_block(file, insn, false))
+ if (!__grow_static_block(file, insn))
break;
}
}
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -61,7 +61,7 @@ struct symbol {
unsigned char bind, type;
unsigned long offset;
unsigned int len;
- bool static_call, non_static_call;
+ unsigned int static_call, non_static_call;
};
struct rela {
