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authorLinus Torvalds <torvalds@linux-foundation.org>2018-02-14 17:02:15 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-14 17:02:15 -0800
commitd4667ca142610961c89ae7c41a823b3358fcdd0e (patch)
treeff43d39e20feaf477a1ceaf35eba841eebd7e0a6 /tools/objtool
parent6556677a80400ca5744340d8ff6fbed22621293e (diff)
parente48657573481a5dff7cfdc3d57005c80aa816500 (diff)
downloadlinux-stericsson-d4667ca142610961c89ae7c41a823b3358fcdd0e.tar.gz
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 PTI and Spectre related fixes and updates from Ingo Molnar: "Here's the latest set of Spectre and PTI related fixes and updates: Spectre: - Add entry code register clearing to reduce the Spectre attack surface - Update the Spectre microcode blacklist - Inline the KVM Spectre helpers to get close to v4.14 performance again. - Fix indirect_branch_prediction_barrier() - Fix/improve Spectre related kernel messages - Fix array_index_nospec_mask() asm constraint - KVM: fix two MSR handling bugs PTI: - Fix a paranoid entry PTI CR3 handling bug - Fix comments objtool: - Fix paranoid_entry() frame pointer warning - Annotate WARN()-related UD2 as reachable - Various fixes - Add Add Peter Zijlstra as objtool co-maintainer Misc: - Various x86 entry code self-test fixes - Improve/simplify entry code stack frame generation and handling after recent heavy-handed PTI and Spectre changes. (There's two more WIP improvements expected here.) - Type fix for cache entries There's also some low risk non-fix changes I've included in this branch to reduce backporting conflicts: - rename a confusing x86_cpu field name - de-obfuscate the naming of single-TLB flushing primitives" * 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits) x86/entry/64: Fix CR3 restore in paranoid_exit() x86/cpu: Change type of x86_cache_size variable to unsigned int x86/spectre: Fix an error message x86/cpu: Rename cpu_data.x86_mask to cpu_data.x86_stepping selftests/x86/mpx: Fix incorrect bounds with old _sigfault x86/mm: Rename flush_tlb_single() and flush_tlb_one() to __flush_tlb_one_[user|kernel]() x86/speculation: Add <asm/msr-index.h> dependency nospec: Move array_index_nospec() parameter checking into separate macro x86/speculation: Fix up array_index_nospec_mask() asm constraint x86/debug: Use UD2 for WARN() x86/debug, objtool: Annotate WARN()-related UD2 as reachable objtool: Fix segfault in ignore_unreachable_insn() selftests/x86: Disable tests requiring 32-bit support on pure 64-bit systems selftests/x86: Do not rely on "int $0x80" in single_step_syscall.c selftests/x86: Do not rely on "int $0x80" in test_mremap_vdso.c selftests/x86: Fix build bug caused by the 5lvl test which has been moved to the VM directory selftests/x86/pkeys: Remove unused functions selftests/x86: Clean up and document sscanf() usage selftests/x86: Fix vDSO selftest segfault for vsyscall=none x86/entry/64: Remove the unused 'icebp' macro ...
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/check.c53
-rw-r--r--tools/objtool/check.h1
2 files changed, 49 insertions, 5 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b00b1896547e..a8cb69a26576 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -852,8 +852,14 @@ static int add_switch_table(struct objtool_file *file, struct symbol *func,
* This is a fairly uncommon pattern which is new for GCC 6. As of this
* writing, there are 11 occurrences of it in the allmodconfig kernel.
*
+ * As of GCC 7 there are quite a few more of these and the 'in between' code
+ * is significant. Esp. with KASAN enabled some of the code between the mov
+ * and jmpq uses .rodata itself, which can confuse things.
+ *
* TODO: Once we have DWARF CFI and smarter instruction decoding logic,
* ensure the same register is used in the mov and jump instructions.
+ *
+ * NOTE: RETPOLINE made it harder still to decode dynamic jumps.
*/
static struct rela *find_switch_table(struct objtool_file *file,
struct symbol *func,
@@ -875,12 +881,25 @@ static struct rela *find_switch_table(struct objtool_file *file,
text_rela->addend + 4);
if (!rodata_rela)
return NULL;
+
file->ignore_unreachables = true;
return rodata_rela;
}
/* case 3 */
- func_for_each_insn_continue_reverse(file, func, insn) {
+ /*
+ * Backward search using the @first_jump_src links, these help avoid
+ * much of the 'in between' code. Which avoids us getting confused by
+ * it.
+ */
+ for (insn = list_prev_entry(insn, list);
+
+ &insn->list != &file->insn_list &&
+ insn->sec == func->sec &&
+ insn->offset >= func->offset;
+
+ insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {
+
if (insn->type == INSN_JUMP_DYNAMIC)
break;
@@ -910,14 +929,32 @@ static struct rela *find_switch_table(struct objtool_file *file,
return NULL;
}
+
static int add_func_switch_tables(struct objtool_file *file,
struct symbol *func)
{
- struct instruction *insn, *prev_jump = NULL;
+ struct instruction *insn, *last = NULL, *prev_jump = NULL;
struct rela *rela, *prev_rela = NULL;
int ret;
func_for_each_insn(file, func, insn) {
+ if (!last)
+ last = insn;
+
+ /*
+ * Store back-pointers for unconditional forward jumps such
+ * that find_switch_table() can back-track using those and
+ * avoid some potentially confusing code.
+ */
+ if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest &&
+ insn->offset > last->offset &&
+ insn->jump_dest->offset > insn->offset &&
+ !insn->jump_dest->first_jump_src) {
+
+ insn->jump_dest->first_jump_src = insn;
+ last = insn->jump_dest;
+ }
+
if (insn->type != INSN_JUMP_DYNAMIC)
continue;
@@ -1899,13 +1936,19 @@ static bool ignore_unreachable_insn(struct instruction *insn)
if (is_kasan_insn(insn) || is_ubsan_insn(insn))
return true;
- if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->jump_dest) {
- insn = insn->jump_dest;
- continue;
+ if (insn->type == INSN_JUMP_UNCONDITIONAL) {
+ if (insn->jump_dest &&
+ insn->jump_dest->func == insn->func) {
+ insn = insn->jump_dest;
+ continue;
+ }
+
+ break;
}
if (insn->offset + insn->len >= insn->func->offset + insn->func->len)
break;
+
insn = list_next_entry(insn, list);
}
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index dbadb304a410..23a1d065cae1 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -47,6 +47,7 @@ struct instruction {
bool alt_group, visited, dead_end, ignore, hint, save, restore, ignore_alts;
struct symbol *call_dest;
struct instruction *jump_dest;
+ struct instruction *first_jump_src;
struct list_head alts;
struct symbol *func;
struct stack_op stack_op;