From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org, jpoimboe@redhat.com, jgross@suse.com, mbenes@suse.com
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: [PATCH v2 12/14] objtool: Allow archs to rewrite retpolines
Date: Thu, 18 Mar 2021 18:11:15 +0100 [thread overview]
Message-ID: <20210318171920.131630843@infradead.org> (raw)
In-Reply-To: 20210318171103.577093939@infradead.org
When retpolines are employed, compilers typically emit calls to
retpoline thunks. Objtool recognises these calls and marks them as
dynamic calls.
Provide infrastructure for architectures to rewrite/augment what the
compiler wrote for us.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
tools/objtool/check.c | 23 +++++++++++++++++++++--
tools/objtool/include/objtool/arch.h | 3 +++
2 files changed, 24 insertions(+), 2 deletions(-)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -852,6 +852,14 @@ __weak bool arch_is_retpoline(struct sym
return false;
}
+
+__weak int arch_rewrite_retpoline(struct objtool_file *file,
+ struct instruction *insn,
+ struct reloc *reloc)
+{
+ return 0;
+}
+
/*
* Find the destination instructions for all jumps.
*/
@@ -885,6 +893,9 @@ static int add_jump_destinations(struct
insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;
insn->retpoline_safe = true;
+
+ arch_rewrite_retpoline(file, insn, reloc);
+
continue;
} else if (insn->func) {
/* internal or external sibling call (with reloc) */
@@ -1036,6 +1047,8 @@ static int add_call_destinations(struct
insn->type = INSN_CALL_DYNAMIC;
insn->retpoline_safe = true;
+ arch_rewrite_retpoline(file, insn, reloc);
+
remove_insn_ops(insn);
continue;
@@ -1212,6 +1225,8 @@ static int handle_group_alt(struct objto
dest_off = arch_jump_destination(insn);
if (dest_off == special_alt->new_off + special_alt->new_len)
insn->jump_dest = next_insn_same_sec(file, last_orig_insn);
+ else
+ insn->jump_dest = find_insn(file, insn->sec, dest_off);
if (!insn->jump_dest) {
WARN_FUNC("can't find alternative jump destination",
@@ -1797,11 +1812,15 @@ static int decode_sections(struct objtoo
if (ret)
return ret;
- ret = add_jump_destinations(file);
+ /*
+ * Must be before add_{jump,call}_destination; for they can add
+ * magic alternatives.
+ */
+ ret = add_special_section_alts(file);
if (ret)
return ret;
- ret = add_special_section_alts(file);
+ ret = add_jump_destinations(file);
if (ret)
return ret;
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -82,6 +82,9 @@ unsigned long arch_jump_destination(stru
unsigned long arch_dest_reloc_offset(int addend);
const char *arch_nop_insn(int len);
+int arch_rewrite_retpoline(struct objtool_file *file,
+ struct instruction *insn,
+ struct reloc *reloc);
int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg);
next prev parent reply other threads:[~2021-03-18 17:24 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-18 17:11 [PATCH v2 00/14] x86,objtool: Optimize !RETPOLINE Peter Zijlstra
2021-03-18 17:11 ` [PATCH v2 01/14] x86: Add insn_decode_kernel() Peter Zijlstra
2021-03-19 10:40 ` Borislav Petkov
2021-03-18 17:11 ` [PATCH v2 02/14] x86/alternatives: Optimize optimize_nops() Peter Zijlstra
2021-03-21 12:06 ` Borislav Petkov
2021-03-22 8:17 ` Peter Zijlstra
2021-03-22 11:07 ` Borislav Petkov
2021-03-18 17:11 ` [PATCH v2 03/14] x86/retpoline: Simplify retpolines Peter Zijlstra
2021-03-19 17:18 ` David Laight
2021-03-22 9:32 ` Peter Zijlstra
2021-03-22 15:41 ` David Laight
2021-03-18 17:11 ` [PATCH v2 04/14] objtool: Correctly handle retpoline thunk calls Peter Zijlstra
2021-03-18 17:11 ` [PATCH v2 05/14] objtool: Per arch retpoline naming Peter Zijlstra
2021-03-19 2:38 ` Josh Poimboeuf
2021-03-19 9:07 ` Peter Zijlstra
2021-03-18 17:11 ` [PATCH v2 06/14] objtool: Fix static_call list generation Peter Zijlstra
2021-03-22 12:44 ` Miroslav Benes
2021-03-18 17:11 ` [PATCH v2 07/14] objtool: Rework rebuild_reloc logic Peter Zijlstra
2021-03-18 17:11 ` [PATCH v2 08/14] objtool: Add elf_create_reloc() helper Peter Zijlstra
2021-03-19 1:42 ` Josh Poimboeuf
2021-03-19 9:47 ` Peter Zijlstra
2021-03-19 15:12 ` Josh Poimboeuf
2021-03-19 15:24 ` Peter Zijlstra
2021-03-19 15:37 ` Josh Poimboeuf
2021-03-18 17:11 ` [PATCH v2 09/14] objtool: Extract elf_strtab_concat() Peter Zijlstra
2021-03-19 2:10 ` Josh Poimboeuf
2021-03-19 9:52 ` Peter Zijlstra
2021-03-18 17:11 ` [PATCH v2 10/14] objtool: Extract elf_symbol_add() Peter Zijlstra
2021-03-19 2:14 ` Josh Poimboeuf
2021-03-19 9:54 ` Peter Zijlstra
2021-03-19 15:04 ` Josh Poimboeuf
2021-03-18 17:11 ` [PATCH v2 11/14] objtool: Add elf_create_undef_symbol() Peter Zijlstra
2021-03-19 2:29 ` Josh Poimboeuf
2021-03-19 7:56 ` Peter Zijlstra
2021-03-18 17:11 ` Peter Zijlstra [this message]
2021-03-19 2:54 ` [PATCH v2 12/14] objtool: Allow archs to rewrite retpolines Josh Poimboeuf
2021-03-19 11:21 ` Peter Zijlstra
2021-03-19 13:28 ` Peter Zijlstra
2021-03-18 17:11 ` [PATCH v2 13/14] objtool: Skip magical retpoline .altinstr_replacement Peter Zijlstra
2021-03-18 17:11 ` [PATCH v2 14/14] objtool,x86: Rewrite retpoline thunk calls Peter Zijlstra
2021-03-19 3:29 ` Josh Poimboeuf
2021-03-19 8:06 ` Peter Zijlstra
2021-03-19 15:30 ` Josh Poimboeuf
2021-03-19 15:56 ` Peter Zijlstra
2021-03-19 22:52 ` Josh Poimboeuf
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