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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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objtool: Handle __sanitize_cov*() tail calls
Turns out the compilers also generate tail calls to __sanitize_cov*(),
make sure to also patch those out in noinstr code.
Fixes: 0f1441b44e ("objtool: Fix noinstr vs KCOV")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20210624095147.818783799@infradead.org
This commit is contained in:
Peter Zijlstra
parent
8b946cc38e
commit
f56dae88a8
3 changed files with 105 additions and 74 deletions
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@ -659,6 +659,26 @@ const char *arch_nop_insn(int len)
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return nops[len-1];
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}
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#define BYTE_RET 0xC3
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const char *arch_ret_insn(int len)
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{
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static const char ret[5][5] = {
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{ BYTE_RET },
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{ BYTE_RET, BYTES_NOP1 },
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{ BYTE_RET, BYTES_NOP2 },
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{ BYTE_RET, BYTES_NOP3 },
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{ BYTE_RET, BYTES_NOP4 },
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};
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if (len < 1 || len > 5) {
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WARN("invalid RET size: %d\n", len);
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return NULL;
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}
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return ret[len-1];
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}
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/* asm/alternative.h ? */
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#define ALTINSTR_FLAG_INV (1 << 15)
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@ -904,6 +904,79 @@ static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *i
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return insn->reloc;
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}
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static void remove_insn_ops(struct instruction *insn)
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{
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struct stack_op *op, *tmp;
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list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
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list_del(&op->list);
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free(op);
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}
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}
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static void add_call_dest(struct objtool_file *file, struct instruction *insn,
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struct symbol *dest, bool sibling)
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{
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struct reloc *reloc = insn_reloc(file, insn);
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insn->call_dest = dest;
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if (!dest)
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return;
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if (insn->call_dest->static_call_tramp) {
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list_add_tail(&insn->call_node,
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&file->static_call_list);
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}
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/*
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* Many compilers cannot disable KCOV with a function attribute
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* so they need a little help, NOP out any KCOV calls from noinstr
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* text.
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*/
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if (insn->sec->noinstr &&
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!strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {
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if (reloc) {
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reloc->type = R_NONE;
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elf_write_reloc(file->elf, reloc);
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}
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elf_write_insn(file->elf, insn->sec,
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insn->offset, insn->len,
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sibling ? arch_ret_insn(insn->len)
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: arch_nop_insn(insn->len));
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insn->type = sibling ? INSN_RETURN : INSN_NOP;
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}
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if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) {
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if (sibling)
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WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec, insn->offset);
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if (reloc) {
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reloc->type = R_NONE;
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elf_write_reloc(file->elf, reloc);
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}
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elf_write_insn(file->elf, insn->sec,
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insn->offset, insn->len,
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arch_nop_insn(insn->len));
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insn->type = INSN_NOP;
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list_add_tail(&insn->mcount_loc_node,
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&file->mcount_loc_list);
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}
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/*
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* Whatever stack impact regular CALLs have, should be undone
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* by the RETURN of the called function.
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*
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* Annotated intra-function calls retain the stack_ops but
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* are converted to JUMP, see read_intra_function_calls().
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*/
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remove_insn_ops(insn);
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}
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/*
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* Find the destination instructions for all jumps.
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*/
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@ -942,11 +1015,7 @@ static int add_jump_destinations(struct objtool_file *file)
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continue;
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} else if (insn->func) {
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/* internal or external sibling call (with reloc) */
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insn->call_dest = reloc->sym;
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if (insn->call_dest->static_call_tramp) {
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list_add_tail(&insn->call_node,
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&file->static_call_list);
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}
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add_call_dest(file, insn, reloc->sym, true);
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continue;
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} else if (reloc->sym->sec->idx) {
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dest_sec = reloc->sym->sec;
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@ -1002,13 +1071,8 @@ static int add_jump_destinations(struct objtool_file *file)
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} else if (insn->jump_dest->func->pfunc != insn->func->pfunc &&
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insn->jump_dest->offset == insn->jump_dest->func->offset) {
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/* internal sibling call (without reloc) */
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insn->call_dest = insn->jump_dest->func;
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if (insn->call_dest->static_call_tramp) {
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list_add_tail(&insn->call_node,
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&file->static_call_list);
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}
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add_call_dest(file, insn, insn->jump_dest->func, true);
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}
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}
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}
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@ -1016,16 +1080,6 @@ static int add_jump_destinations(struct objtool_file *file)
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return 0;
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}
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static void remove_insn_ops(struct instruction *insn)
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{
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struct stack_op *op, *tmp;
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list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) {
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list_del(&op->list);
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free(op);
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}
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}
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static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
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{
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struct symbol *call_dest;
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@ -1044,6 +1098,7 @@ static int add_call_destinations(struct objtool_file *file)
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{
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struct instruction *insn;
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unsigned long dest_off;
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struct symbol *dest;
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struct reloc *reloc;
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for_each_insn(file, insn) {
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@ -1053,7 +1108,9 @@ static int add_call_destinations(struct objtool_file *file)
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reloc = insn_reloc(file, insn);
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if (!reloc) {
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dest_off = arch_jump_destination(insn);
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insn->call_dest = find_call_destination(insn->sec, dest_off);
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dest = find_call_destination(insn->sec, dest_off);
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add_call_dest(file, insn, dest, false);
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if (insn->ignore)
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continue;
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@ -1071,9 +1128,8 @@ static int add_call_destinations(struct objtool_file *file)
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} else if (reloc->sym->type == STT_SECTION) {
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dest_off = arch_dest_reloc_offset(reloc->addend);
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insn->call_dest = find_call_destination(reloc->sym->sec,
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dest_off);
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if (!insn->call_dest) {
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dest = find_call_destination(reloc->sym->sec, dest_off);
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if (!dest) {
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WARN_FUNC("can't find call dest symbol at %s+0x%lx",
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insn->sec, insn->offset,
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reloc->sym->sec->name,
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@ -1081,6 +1137,8 @@ static int add_call_destinations(struct objtool_file *file)
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return -1;
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}
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add_call_dest(file, insn, dest, false);
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} else if (arch_is_retpoline(reloc->sym)) {
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/*
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* Retpoline calls are really dynamic calls in
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@ -1096,55 +1154,7 @@ static int add_call_destinations(struct objtool_file *file)
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continue;
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} else
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insn->call_dest = reloc->sym;
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if (insn->call_dest && insn->call_dest->static_call_tramp) {
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list_add_tail(&insn->call_node,
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&file->static_call_list);
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}
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/*
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* Many compilers cannot disable KCOV with a function attribute
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* so they need a little help, NOP out any KCOV calls from noinstr
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* text.
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*/
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if (insn->sec->noinstr &&
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!strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) {
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if (reloc) {
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reloc->type = R_NONE;
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elf_write_reloc(file->elf, reloc);
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}
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elf_write_insn(file->elf, insn->sec,
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insn->offset, insn->len,
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arch_nop_insn(insn->len));
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insn->type = INSN_NOP;
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}
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if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) {
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if (reloc) {
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reloc->type = R_NONE;
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elf_write_reloc(file->elf, reloc);
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}
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elf_write_insn(file->elf, insn->sec,
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insn->offset, insn->len,
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arch_nop_insn(insn->len));
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insn->type = INSN_NOP;
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list_add_tail(&insn->mcount_loc_node,
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&file->mcount_loc_list);
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}
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/*
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* Whatever stack impact regular CALLs have, should be undone
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* by the RETURN of the called function.
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*
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* Annotated intra-function calls retain the stack_ops but
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* are converted to JUMP, see read_intra_function_calls().
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*/
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remove_insn_ops(insn);
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add_call_dest(file, insn, reloc->sym, false);
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}
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return 0;
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@ -82,6 +82,7 @@ unsigned long arch_jump_destination(struct instruction *insn);
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unsigned long arch_dest_reloc_offset(int addend);
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const char *arch_nop_insn(int len);
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const char *arch_ret_insn(int len);
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int arch_decode_hint_reg(u8 sp_reg, int *base);
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