From: Peter Zijlstra <peterz@infradead.org>
To: tglx@linutronix.de, jpoimboe@redhat.com
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [RFC][PATCH 00/16] objtool: vmlinux.o and noinstr validation
Date: Thu, 12 Mar 2020 23:23:24 +0100 [thread overview]
Message-ID: <20200312222324.GD5086@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20200312162337.GU12561@hirez.programming.kicks-ass.net>
On Thu, Mar 12, 2020 at 05:23:37PM +0100, Peter Zijlstra wrote:
> So one of the problem i've ran into while playing with this and Thomas'
> patches is that it is 'difficult' to deal with indirect function calls.
>
> objtool basically gives up instantly.
>
> I know smatch has passes were it looks for function pointer assignments
> and carries that forward into it's callchain generation. Doing something
> like that for objtool is going to be 'fun'...
>
> For now I've got limited success dodging a few instances with
> __always_inline (which then results in the compiler resolving the
> indirection).
Here's a little something that at least detects 'immediate' function
pointers crossing the boundary.
It's slow though; it almost tripples the runtime. But I'm too tired to
make it fast, maybe tomorrow.
---
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -247,6 +247,9 @@ static int decode_instructions(struct ob
strncmp(sec->name, ".discard.", 9))
sec->text = true;
+ if (!strcmp(sec->name, ".noinstr.text"))
+ sec->noinstr = true;
+
for (offset = 0; offset < sec->len; offset += insn->len) {
insn = malloc(sizeof(*insn));
if (!insn) {
@@ -2040,6 +2043,28 @@ static int validate_return(struct symbol
return 0;
}
+static int validate_rela(struct instruction *insn, struct insn_state *state)
+{
+ struct section *sec;
+ struct rela *rela;
+
+ if (!(state->noinstr && state->instr <= 0))
+ return 0;
+
+ rela = find_rela_by_dest_range(insn->sec, insn->offset, insn->len);
+ if (!rela || !rela->sym || !rela->sym->sec)
+ return 0;
+
+ sec = rela->sym->sec;
+ if (sec->text && !sec->noinstr) {
+ WARN_FUNC("loading non-noinstr function pointer\n",
+ insn->sec, insn->offset);
+ return 1;
+ }
+
+ return 0;
+}
+
/*
* Follow the branch starting at the given instruction, and recursively follow
* any other branches (jumps). Meanwhile, track the frame pointer state at
@@ -2222,6 +2247,10 @@ static int validate_branch(struct objtoo
return 0;
case INSN_STACK:
+ ret = validate_rela(insn, &state);
+ if (ret)
+ return ret;
+
if (update_insn_state(insn, &state))
return 1;
@@ -2285,6 +2314,10 @@ static int validate_branch(struct objtoo
break;
default:
+ ret = validate_rela(insn, &state);
+ if (ret)
+ return ret;
+
break;
}
@@ -2442,8 +2475,8 @@ static int validate_sec_functions(struct
* not correctly determine insn->call_dest->sec (external symbols do
* not have a section).
*/
- if (vmlinux && !strcmp(sec->name, ".noinstr.text"))
- state.noinstr = true;
+ if (vmlinux)
+ state.noinstr = sec->noinstr;
list_for_each_entry(func, &sec->symbol_list, list) {
if (func->type != STT_FUNC)
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -43,7 +43,7 @@ struct section {
char *name;
int idx;
unsigned int len;
- bool changed, text, rodata;
+ bool changed, text, rodata, noinstr;
};
struct symbol {
next prev parent reply other threads:[~2020-03-12 22:23 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-12 13:41 [RFC][PATCH 00/16] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 01/16] objtool: Introduce validate_return() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 02/16] objtool: Rename func_for_each_insn() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 03/16] objtool: Rename func_for_each_insn_all() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 04/16] objtool: Annotate identity_mapped() Peter Zijlstra
2020-03-13 14:34 ` Peter Zijlstra
2020-03-15 15:45 ` Josh Poimboeuf
2020-03-13 16:46 ` Brian Gerst
2020-03-13 17:22 ` Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 05/16] objtool: Optimize find_symbol_by_index() Peter Zijlstra
2020-03-15 16:09 ` Josh Poimboeuf
2020-03-15 16:18 ` Josh Poimboeuf
2020-03-15 16:10 ` Josh Poimboeuf
2020-03-17 11:55 ` Miroslav Benes
2020-03-17 14:08 ` Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 06/16] objtool: Add a statistics mode Peter Zijlstra
2020-03-15 16:20 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 07/16] objtool: Optimize find_section_by_index() Peter Zijlstra
2020-03-15 16:24 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 08/16] Optimize find_section_by_name() Peter Zijlstra
2020-03-15 16:25 ` Josh Poimboeuf
2020-03-17 12:22 ` Miroslav Benes
2020-03-17 14:10 ` Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 09/16] objtool: Optimize find_symbol_*() and read_symbols() Peter Zijlstra
2020-03-15 15:48 ` Josh Poimboeuf
2020-03-15 16:41 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 10/16] objtool: Resize insn_hash Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 11/16] objtool: Optimize find_symbol_by_name() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 12/16] objtool: Optimize read_sections() Peter Zijlstra
2020-03-15 16:53 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 13/16] objtool: Delete cleanup() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 14/16] objtool: Optimize find_rela_by_dest_range() Peter Zijlstra
2020-03-12 13:41 ` [RFC][PATCH 15/16] objtool: Implement noinstr validation Peter Zijlstra
2020-03-15 18:03 ` Josh Poimboeuf
2020-03-16 13:24 ` Peter Zijlstra
2020-03-16 16:19 ` Josh Poimboeuf
2020-03-16 16:21 ` Josh Poimboeuf
2020-03-16 16:46 ` Peter Zijlstra
2020-03-16 16:48 ` Peter Zijlstra
2020-03-16 19:20 ` Josh Poimboeuf
2020-03-12 13:41 ` [RFC][PATCH 16/16] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-03-12 21:57 ` [RFC][PATCH v2 " Peter Zijlstra
2020-03-12 16:23 ` [RFC][PATCH 00/16] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-12 17:44 ` Josh Poimboeuf
2020-03-12 22:23 ` Peter Zijlstra [this message]
2020-03-17 0:56 ` Masami Hiramatsu
2020-03-17 9:26 ` Thomas Gleixner
2020-03-17 14:20 ` Masami Hiramatsu
2020-03-17 12:14 ` Peter Zijlstra
2020-03-15 18:12 ` Josh Poimboeuf
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