From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, jpoimboe@redhat.com
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
peterz@infradead.org, mhiramat@kernel.org, mbenes@suse.cz,
brgerst@gmail.com
Subject: [PATCH v3 18/26] objtool: Fix !CFI insn_state propagation
Date: Tue, 24 Mar 2020 16:31:31 +0100 [thread overview]
Message-ID: <20200324160924.987489248@infradead.org> (raw)
In-Reply-To: 20200324153113.098167666@infradead.org
Objtool keeps per instruction CFI state in struct insn_state and will
save/restore this where required. However, insn_state has grown some
!CFI state, and this must not be saved/restored (and thus lost).
Fix this by explicitly preserving the !CFI state and clarify by
restucturing the code and adding a comment.
XXX, the insn==first condition is not handled right.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
tools/objtool/check.c | 95 +++++++++++++++++++++++++++++---------------------
tools/objtool/check.h | 8 ++++
2 files changed, 64 insertions(+), 39 deletions(-)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2033,6 +2033,59 @@ static int validate_return(struct symbol
return 0;
}
+static int apply_insn_hint(struct objtool_file *file, struct section *sec,
+ struct symbol *func, struct instruction *first,
+ struct instruction *insn, struct insn_state *state)
+{
+ struct insn_state old = *state;
+
+ if (insn->restore) {
+ struct instruction *save_insn, *i;
+
+ i = insn;
+ save_insn = NULL;
+ sym_for_each_insn_continue_reverse(file, func, i) {
+ if (i->save) {
+ save_insn = i;
+ break;
+ }
+ }
+
+ if (!save_insn) {
+ WARN_FUNC("no corresponding CFI save for CFI restore",
+ sec, insn->offset);
+ return 1;
+ }
+
+ if (!save_insn->visited) {
+ /*
+ * Oops, no state to copy yet.
+ * Hopefully we can reach this
+ * instruction from another branch
+ * after the save insn has been
+ * visited.
+ */
+ if (insn == first)
+ return 0; // XXX
+
+ WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
+ sec, insn->offset);
+ return 1;
+ }
+
+ insn->state = save_insn->state;
+ }
+
+ *state = insn->state;
+
+ /* restore !CFI state */
+ state->df = old.df;
+ state->uaccess = old.uaccess;
+ state->uaccess_stack = old.uaccess_stack;
+
+ return 0;
+}
+
/*
* Follow the branch starting at the given instruction, and recursively follow
* any other branches (jumps). Meanwhile, track the frame pointer state at
@@ -2082,45 +2135,9 @@ static int validate_branch(struct objtoo
}
if (insn->hint) {
- if (insn->restore) {
- struct instruction *save_insn, *i;
-
- i = insn;
- save_insn = NULL;
- sym_for_each_insn_continue_reverse(file, func, i) {
- if (i->save) {
- save_insn = i;
- break;
- }
- }
-
- if (!save_insn) {
- WARN_FUNC("no corresponding CFI save for CFI restore",
- sec, insn->offset);
- return 1;
- }
-
- if (!save_insn->visited) {
- /*
- * Oops, no state to copy yet.
- * Hopefully we can reach this
- * instruction from another branch
- * after the save insn has been
- * visited.
- */
- if (insn == first)
- return 0;
-
- WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
- sec, insn->offset);
- return 1;
- }
-
- insn->state = save_insn->state;
- }
-
- state = insn->state;
-
+ ret = apply_insn_hint(file, sec, func, first, insn, &state);
+ if (ret)
+ return ret;
} else
insn->state = state;
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -13,6 +13,14 @@
#include "orc.h"
#include <linux/hashtable.h>
+/*
+ * This structure (mostly) contains the instruction level CFI (Call Frame
+ * Information) and is saved/restored where appropriate; see validate_branch().
+ *
+ * However it does also contain a limited amount of !CFI state; this state must
+ * not be saved/restored along with the CFI information and is manually
+ * preserved. See apply_insn_hint().
+ */
struct insn_state {
struct cfi_reg cfa;
struct cfi_reg regs[CFI_NUM_REGS];
next prev parent reply other threads:[~2020-03-24 16:13 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 15:31 [PATCH v3 00/26] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 01/26] objtool: Introduce validate_return() Peter Zijlstra
2020-03-25 8:39 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 02/26] objtool: Rename func_for_each_insn() Peter Zijlstra
2020-03-25 8:43 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 03/26] objtool: Rename func_for_each_insn_all() Peter Zijlstra
2020-03-25 8:44 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 04/26] x86/kexec: Use RIP relative addressing Peter Zijlstra
2020-03-25 9:34 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 05/26] x86/kexec: Make relocate_kernel_64.S objtool clean Peter Zijlstra
2020-03-24 20:55 ` Josh Poimboeuf
2020-03-25 9:56 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 06/26] objtool: Optimize find_symbol_by_index() Peter Zijlstra
2020-03-25 10:01 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 07/26] objtool: Add a statistics mode Peter Zijlstra
2020-03-25 10:10 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 08/26] objtool: Optimize find_section_by_index() Peter Zijlstra
2020-03-25 10:12 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 09/26] objtool: Optimize find_section_by_name() Peter Zijlstra
2020-03-25 10:18 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 10/26] objtool: Optimize find_symbol_*() and read_symbols() Peter Zijlstra
2020-03-25 10:20 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 11/26] objtool: Rename find_containing_func() Peter Zijlstra
2020-03-25 10:21 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 12/26] objtool: Resize insn_hash Peter Zijlstra
2020-03-25 10:21 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 13/26] objtool: Optimize find_symbol_by_name() Peter Zijlstra
2020-03-25 10:25 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 14/26] objtool: Optimize read_sections() Peter Zijlstra
2020-03-25 12:10 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-04-21 14:47 ` [PATCH v3 14/26] " youling257
2020-04-21 15:49 ` Peter Zijlstra
2020-04-21 15:57 ` Borislav Petkov
2020-04-21 17:50 ` youling 257
2020-03-24 15:31 ` [PATCH v3 15/26] objtool: Delete cleanup() Peter Zijlstra
2020-03-25 12:11 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 16/26] objtool: Optimize find_rela_by_dest_range() Peter Zijlstra
2020-03-25 12:19 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 17/26] objtool: Re-arrange validate_functions() Peter Zijlstra
2020-03-24 21:10 ` Josh Poimboeuf
2020-03-24 21:15 ` Peter Zijlstra
2020-03-25 12:22 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` Peter Zijlstra [this message]
2020-03-24 21:40 ` [PATCH v3 18/26] objtool: Fix !CFI insn_state propagation Josh Poimboeuf
2020-03-24 22:11 ` Peter Zijlstra
2020-03-24 23:00 ` Peter Zijlstra
2020-03-25 14:39 ` Josh Poimboeuf
2020-03-25 14:41 ` [PATCH v3.1 18a/26] objtool: Remove CFI save/restore special case Peter Zijlstra
2020-03-25 14:42 ` [PATCH v3.1 18b/26] objtool: Factor out CFI hints Peter Zijlstra
2020-03-25 14:43 ` [PATCH v3.1 18c/26] objtool: Rename struct cfi_state Peter Zijlstra
2020-03-25 14:43 ` [PATCH v3.1 18d/26] objtool: Fix !CFI insn_state propagation Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 19/26] objtool: Implement noinstr validation Peter Zijlstra
2020-03-24 21:41 ` Josh Poimboeuf
2020-03-25 14:44 ` [PATCH v3.1 " Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 20/26] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 21/26] objtool: Use sec_offset_hash() for insn_hash Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 22/26] objtool: Detect loading function pointers across noinstr Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 23/26] kbuild/objtool: Add objtool-vmlinux.o pass Peter Zijlstra
2020-03-24 22:03 ` Josh Poimboeuf
2020-03-24 22:05 ` Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 24/26] objtool: Avoid iterating !text section symbols Peter Zijlstra
2020-03-24 22:09 ` Josh Poimboeuf
2020-03-24 15:31 ` [PATCH v3 25/26] objtool: Rearrange validate_section() Peter Zijlstra
2020-03-24 22:10 ` Josh Poimboeuf
2020-03-24 15:31 ` [PATCH v3 26/26] objtool: Add STT_NOTYPE noinstr validation Peter Zijlstra
2020-03-24 22:16 ` Josh Poimboeuf
2020-03-24 22:34 ` Peter Zijlstra
2020-03-25 14:42 ` Josh Poimboeuf
2020-03-25 15:53 ` Peter Zijlstra
2020-03-25 16:40 ` Josh Poimboeuf
2020-03-25 16:50 ` Peter Zijlstra
2020-03-26 8:01 ` Julien Thierry
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