lkml.org 
[lkml]   [2019]   [Mar]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 07/25] x86/nospec,objtool: Introduce ANNOTATE_IGNORE_ALTERNATIVE
To facillitate other usage of ignoring alternatives; rename
ANNOTATE_NOSPEC_IGNORE to ANNOTATE_IGNORE_ALTERNATIVE.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/alternative-asm.h | 11 +++++++++++
arch/x86/include/asm/alternative.h | 10 ++++++++++
arch/x86/include/asm/nospec-branch.h | 28 +++++++++-------------------
tools/objtool/check.c | 8 ++++----
4 files changed, 34 insertions(+), 23 deletions(-)

--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -20,6 +20,17 @@
#endif

/*
+ * objtool annotation to ignore the alternatives and only consider the original
+ * instruction(s).
+ */
+.macro ANNOTATE_IGNORE_ALTERNATIVE
+ .Lannotate_\@:
+ .pushsection .discard.ignore_alts
+ .long .Lannotate_\@ - .
+ .popsection
+.endm
+
+/*
* Issue one struct alt_instr descriptor entry (need to put it into
* the section .altinstructions, see below). This entry contains
* enough information for the alternatives patching code to patch an
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -45,6 +45,16 @@
#define LOCK_PREFIX ""
#endif

+/*
+ * objtool annotation to ignore the alternatives and only consider the original
+ * instruction(s).
+ */
+#define ANNOTATE_IGNORE_ALTERNATIVE \
+ "999:\n\t" \
+ ".pushsection .discard.ignore_alts\n\t" \
+ ".long 999b - .\n\t" \
+ ".popsection\n\t"
+
struct alt_instr {
s32 instr_offset; /* original instruction */
s32 repl_offset; /* offset to replacement instruction */
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -11,6 +11,15 @@
#include <asm/msr-index.h>

/*
+ * This should be used immediately before a retpoline alternative. It tells
+ * objtool where the retpolines are so that it can make sense of the control
+ * flow by just reading the original instruction(s) and ignoring the
+ * alternatives.
+ */
+#define ANNOTATE_NOSPEC_ALTERNATIVE \
+ ANNOTATE_IGNORE_ALTERNATIVE
+
+/*
* Fill the CPU return stack buffer.
*
* Each entry in the RSB, if used for a speculative 'ret', contains an
@@ -57,19 +66,6 @@
#ifdef __ASSEMBLY__

/*
- * This should be used immediately before a retpoline alternative. It tells
- * objtool where the retpolines are so that it can make sense of the control
- * flow by just reading the original instruction(s) and ignoring the
- * alternatives.
- */
-.macro ANNOTATE_NOSPEC_ALTERNATIVE
- .Lannotate_\@:
- .pushsection .discard.nospec
- .long .Lannotate_\@ - .
- .popsection
-.endm
-
-/*
* This should be used immediately before an indirect jump/call. It tells
* objtool the subsequent indirect jump/call is vouched safe for retpoline
* builds.
@@ -152,12 +148,6 @@

#else /* __ASSEMBLY__ */

-#define ANNOTATE_NOSPEC_ALTERNATIVE \
- "999:\n\t" \
- ".pushsection .discard.nospec\n\t" \
- ".long 999b - .\n\t" \
- ".popsection\n\t"
-
#define ANNOTATE_RETPOLINE_SAFE \
"999:\n\t" \
".pushsection .discard.retpoline_safe\n\t" \
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -457,13 +457,13 @@ static void add_ignores(struct objtool_f
* But it at least allows objtool to understand the control flow *around* the
* retpoline.
*/
-static int add_nospec_ignores(struct objtool_file *file)
+static int add_ignore_alternatives(struct objtool_file *file)
{
struct section *sec;
struct rela *rela;
struct instruction *insn;

- sec = find_section_by_name(file->elf, ".rela.discard.nospec");
+ sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
if (!sec)
return 0;

@@ -475,7 +475,7 @@ static int add_nospec_ignores(struct obj

insn = find_insn(file, rela->sym->sec, rela->addend);
if (!insn) {
- WARN("bad .discard.nospec entry");
+ WARN("bad .discard.ignore_alts entry");
return -1;
}

@@ -1239,7 +1239,7 @@ static int decode_sections(struct objtoo

add_ignores(file);

- ret = add_nospec_ignores(file);
+ ret = add_ignore_alternatives(file);
if (ret)
return ret;


\
 
 \ /
  Last update: 2019-03-18 16:55    [W:0.278 / U:0.672 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site