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| author | Peter Zijlstra <peterz@infradead.org> | 2019-07-24 17:47:26 -0500 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-07-25 08:36:39 +0200 |
| commit | 882a0db9d143e5e8dac54b96e83135bccd1f68d1 (patch) | |
| tree | 1382ff4f2c0e99fb8d32b6869406b27a3888c23f | |
| parent | b68b9907069a8d3a65bc16a35360bf8f8603c8fa (diff) | |
| download | linux-882a0db9d143e5e8dac54b96e83135bccd1f68d1.tar.gz linux-882a0db9d143e5e8dac54b96e83135bccd1f68d1.tar.bz2 linux-882a0db9d143e5e8dac54b96e83135bccd1f68d1.zip | |
objtool: Improve UACCESS coverage
A clang build reported an (obvious) double CLAC while a GCC build did not;
it turns out that objtool only re-visits instructions if the first visit
was with AC=0. If OTOH the first visit was with AC=1, it completely ignores
any subsequent visit, even when it has AC=0.
Fix this by using a visited mask instead of a boolean, and (explicitly)
mark the AC state.
$ ./objtool check -b --no-fp --retpoline --uaccess drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x22: redundant UACCESS disable
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xea: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xd9: (alt)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xb2: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x39: (branch)
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x0: <=== (func)
Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/617
Link: https://lkml.kernel.org/r/5359166aad2d53f3145cd442d83d0e5115e0cd17.1564007838.git.jpoimboe@redhat.com
| -rw-r--r-- | tools/objtool/check.c | 7 | ||||
| -rw-r--r-- | tools/objtool/check.h | 3 |
2 files changed, 6 insertions, 4 deletions
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 5f26620f13f5..176f2f084060 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1946,6 +1946,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, struct alternative *alt; struct instruction *insn, *next_insn; struct section *sec; + u8 visited; int ret; insn = first; @@ -1972,12 +1973,12 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 1; } + visited = 1 << state.uaccess; if (insn->visited) { if (!insn->hint && !insn_state_match(insn, &state)) return 1; - /* If we were here with AC=0, but now have AC=1, go again */ - if (insn->state.uaccess || !state.uaccess) + if (insn->visited & visited) return 0; } @@ -2024,7 +2025,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, } else insn->state = state; - insn->visited = true; + insn->visited |= visited; if (!insn->ignore_alts) { bool skip_orig = false; diff --git a/tools/objtool/check.h b/tools/objtool/check.h index b881fafcf55d..6d875ca6fce0 100644 --- a/tools/objtool/check.h +++ b/tools/objtool/check.h @@ -33,8 +33,9 @@ struct instruction { unsigned int len; enum insn_type type; unsigned long immediate; - bool alt_group, visited, dead_end, ignore, hint, save, restore, ignore_alts; + bool alt_group, dead_end, ignore, hint, save, restore, ignore_alts; bool retpoline_safe; + u8 visited; struct symbol *call_dest; struct instruction *jump_dest; struct instruction *first_jump_src; |