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author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-14 17:02:15 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-14 17:02:15 -0800 |
commit | d4667ca142610961c89ae7c41a823b3358fcdd0e (patch) | |
tree | ff43d39e20feaf477a1ceaf35eba841eebd7e0a6 /tools/objtool | |
parent | 6556677a80400ca5744340d8ff6fbed22621293e (diff) | |
parent | e48657573481a5dff7cfdc3d57005c80aa816500 (diff) | |
download | linux-d4667ca142610961c89ae7c41a823b3358fcdd0e.tar.bz2 |
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.c | 53 | ||||
-rw-r--r-- | tools/objtool/check.h | 1 |
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; |