From: Josh Poimboeuf <jpoimboe@redhat.com>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Sami Tolvanen <samitolvanen@google.com>,
Sedat Dilek <sedat.dilek@gmail.com>,
Kees Cook <keescook@chromium.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux@googlegroups.com,
Miroslav Benes <mbenes@suse.cz>
Subject: [PATCH 09/21] objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC
Date: Thu, 14 Jan 2021 13:40:05 -0600 [thread overview]
Message-ID: <86820e8b33d36ee9c28adcf3d2525f0cd05fb0ad.1610652862.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1610652862.git.jpoimboe@redhat.com>
The ORC metadata generated for UNWIND_HINT_FUNC isn't actually very
func-like. With certain usages it can cause stack state mismatches
because it doesn't set the return address (CFI_RA).
Also, users of UNWIND_HINT_RET_OFFSET no longer need to set a custom
return stack offset. Instead they just need to specify a func-like
situation, so the current ret_offset code is hacky for no good reason.
Solve both problems by simplifying the RET_OFFSET handling and
converting it into a more useful UNWIND_HINT_FUNC.
If we end up needing the old 'ret_offset' functionality again in the
future, we should be able to support it pretty easily with the addition
of a custom 'sp_offset' in UNWIND_HINT_FUNC.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
arch/x86/include/asm/unwind_hints.h | 13 ++--------
arch/x86/kernel/ftrace_64.S | 2 +-
arch/x86/lib/retpoline.S | 2 +-
include/linux/objtool.h | 5 +++-
tools/include/linux/objtool.h | 5 +++-
tools/objtool/arch/x86/decode.c | 4 ++--
tools/objtool/check.c | 37 ++++++++++++-----------------
tools/objtool/check.h | 1 -
8 files changed, 29 insertions(+), 40 deletions(-)
diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 664d4610d700..8e574c0afef8 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -48,17 +48,8 @@
UNWIND_HINT_REGS base=\base offset=\offset partial=1
.endm
-.macro UNWIND_HINT_FUNC sp_offset=8
- UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=\sp_offset type=UNWIND_HINT_TYPE_CALL
-.endm
-
-/*
- * RET_OFFSET: Used on instructions that terminate a function; mostly RETURN
- * and sibling calls. On these, sp_offset denotes the expected offset from
- * initial_func_cfi.
- */
-.macro UNWIND_HINT_RET_OFFSET sp_offset=8
- UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_RET_OFFSET sp_offset=\sp_offset
+.macro UNWIND_HINT_FUNC
+ UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=8 type=UNWIND_HINT_TYPE_FUNC
.endm
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 58d125ed9d1a..1bf568d901b1 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -277,7 +277,7 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL)
restore_mcount_regs 8
/* Restore flags */
popfq
- UNWIND_HINT_RET_OFFSET
+ UNWIND_HINT_FUNC
jmp ftrace_epilogue
SYM_FUNC_END(ftrace_regs_caller)
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index b4c43a9b1483..f6fb1d218dcc 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -28,7 +28,7 @@ SYM_FUNC_START_NOALIGN(__x86_retpoline_\reg)
jmp .Lspec_trap_\@
.Ldo_rop_\@:
mov %\reg, (%_ASM_SP)
- UNWIND_HINT_RET_OFFSET
+ UNWIND_HINT_FUNC
ret
SYM_FUNC_END(__x86_retpoline_\reg)
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index add1c6eb157e..7e72d975cb76 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -29,11 +29,14 @@ struct unwind_hint {
*
* UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
* sp_reg+sp_offset points to the iret return frame.
+ *
+ * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
+ * Useful for code which doesn't have an ELF function annotation.
*/
#define UNWIND_HINT_TYPE_CALL 0
#define UNWIND_HINT_TYPE_REGS 1
#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
-#define UNWIND_HINT_TYPE_RET_OFFSET 3
+#define UNWIND_HINT_TYPE_FUNC 3
#ifdef CONFIG_STACK_VALIDATION
diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h
index add1c6eb157e..7e72d975cb76 100644
--- a/tools/include/linux/objtool.h
+++ b/tools/include/linux/objtool.h
@@ -29,11 +29,14 @@ struct unwind_hint {
*
* UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
* sp_reg+sp_offset points to the iret return frame.
+ *
+ * UNWIND_HINT_FUNC: Generate the unwind metadata of a callable function.
+ * Useful for code which doesn't have an ELF function annotation.
*/
#define UNWIND_HINT_TYPE_CALL 0
#define UNWIND_HINT_TYPE_REGS 1
#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
-#define UNWIND_HINT_TYPE_RET_OFFSET 3
+#define UNWIND_HINT_TYPE_FUNC 3
#ifdef CONFIG_STACK_VALIDATION
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index cde9c36e40ae..6f5a45754ad8 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -563,8 +563,8 @@ void arch_initial_func_cfi_state(struct cfi_init_state *state)
state->cfa.offset = 8;
/* initial RA (return address) */
- state->regs[16].base = CFI_CFA;
- state->regs[16].offset = -8;
+ state->regs[CFI_RA].base = CFI_CFA;
+ state->regs[CFI_RA].offset = -8;
}
const char *arch_nop_insn(int len)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index d833855f3aa8..6636f4fd694a 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1400,13 +1400,20 @@ static int add_jump_table_alts(struct objtool_file *file)
return 0;
}
+static void set_func_state(struct cfi_state *state)
+{
+ state->cfa = initial_func_cfi.cfa;
+ memcpy(&state->regs, &initial_func_cfi.regs,
+ CFI_NUM_REGS * sizeof(struct cfi_reg));
+ state->stack_size = initial_func_cfi.cfa.offset;
+}
+
static int read_unwind_hints(struct objtool_file *file)
{
struct section *sec, *relocsec;
struct reloc *reloc;
struct unwind_hint *hint;
struct instruction *insn;
- struct cfi_reg *cfa;
int i;
sec = find_section_by_name(file->elf, ".discard.unwind_hints");
@@ -1441,22 +1448,20 @@ static int read_unwind_hints(struct objtool_file *file)
return -1;
}
- cfa = &insn->cfi.cfa;
+ insn->hint = true;
- if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) {
- insn->ret_offset = hint->sp_offset;
+ if (hint->type == UNWIND_HINT_TYPE_FUNC) {
+ set_func_state(&insn->cfi);
continue;
}
- insn->hint = true;
-
if (arch_decode_hint_reg(insn, hint->sp_reg)) {
WARN_FUNC("unsupported unwind_hint sp base reg %d",
insn->sec, insn->offset, hint->sp_reg);
return -1;
}
- cfa->offset = hint->sp_offset;
+ insn->cfi.cfa.offset = hint->sp_offset;
insn->cfi.type = hint->type;
insn->cfi.end = hint->end;
}
@@ -1712,27 +1717,18 @@ static bool is_fentry_call(struct instruction *insn)
static bool has_modified_stack_frame(struct instruction *insn, struct insn_state *state)
{
- u8 ret_offset = insn->ret_offset;
struct cfi_state *cfi = &state->cfi;
int i;
if (cfi->cfa.base != initial_func_cfi.cfa.base || cfi->drap)
return true;
- if (cfi->cfa.offset != initial_func_cfi.cfa.offset + ret_offset)
+ if (cfi->cfa.offset != initial_func_cfi.cfa.offset)
return true;
- if (cfi->stack_size != initial_func_cfi.cfa.offset + ret_offset)
+ if (cfi->stack_size != initial_func_cfi.cfa.offset)
return true;
- /*
- * If there is a ret offset hint then don't check registers
- * because a callee-saved register might have been pushed on
- * the stack.
- */
- if (ret_offset)
- return false;
-
for (i = 0; i < CFI_NUM_REGS; i++) {
if (cfi->regs[i].base != initial_func_cfi.regs[i].base ||
cfi->regs[i].offset != initial_func_cfi.regs[i].offset)
@@ -2824,10 +2820,7 @@ static int validate_section(struct objtool_file *file, struct section *sec)
continue;
init_insn_state(&state, sec);
- state.cfi.cfa = initial_func_cfi.cfa;
- memcpy(&state.cfi.regs, &initial_func_cfi.regs,
- CFI_NUM_REGS * sizeof(struct cfi_reg));
- state.cfi.stack_size = initial_func_cfi.cfa.offset;
+ set_func_state(&state.cfi);
warnings += validate_symbol(file, sec, func, &state);
}
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index 2804848e628e..4615ca210fae 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -33,7 +33,6 @@ struct instruction {
bool retpoline_safe;
s8 instr;
u8 visited;
- u8 ret_offset;
int alt_group;
struct symbol *call_dest;
struct instruction *jump_dest;
--
2.29.2
next prev parent reply other threads:[~2021-01-14 19:43 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-14 19:39 [PATCH 00/21] objtool: vmlinux.o and CLANG LTO support Josh Poimboeuf
2021-01-14 19:39 ` [PATCH 01/21] objtool: Fix seg fault in BT_FUNC() with fake jump Josh Poimboeuf
2021-01-14 20:04 ` Josh Poimboeuf
2021-01-14 19:39 ` [PATCH 02/21] objtool: Fix error handling for STD/CLD warnings Josh Poimboeuf
2021-01-14 19:39 ` [PATCH 03/21] objtool: Fix retpoline detection in asm code Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 04/21] objtool: Fix ".cold" section suffix check for newer versions of GCC Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 05/21] objtool: Support retpoline jump detection for vmlinux.o Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 06/21] x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub Josh Poimboeuf
2021-01-14 20:42 ` Steven Rostedt
2021-01-14 19:40 ` [PATCH 07/21] objtool: Assume only ELF functions do sibling calls Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 08/21] objtool: Add asm version of STACK_FRAME_NON_STANDARD Josh Poimboeuf
2021-01-14 19:40 ` Josh Poimboeuf [this message]
2021-01-14 19:40 ` [PATCH 10/21] objtool: Add xen_start_kernel() to noreturn list Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 11/21] objtool: Move unsuffixed symbol conversion to a helper function Josh Poimboeuf
2021-01-14 20:55 ` [PATCH v1.1 " Josh Poimboeuf
2021-01-14 21:30 ` Sedat Dilek
2021-01-14 19:40 ` [PATCH 12/21] objtool: Add CONFIG_CFI_CLANG support Josh Poimboeuf
2021-01-14 20:49 ` Sami Tolvanen
2021-01-14 20:52 ` Josh Poimboeuf
2021-01-14 20:56 ` [PATCH v1.1 " Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 13/21] x86/xen: Support objtool validation in xen-asm.S Josh Poimboeuf
2021-01-15 0:31 ` boris.ostrovsky
2021-01-14 19:40 ` [PATCH 14/21] x86/xen: Support objtool vmlinux.o validation in xen-head.S Josh Poimboeuf
2021-01-15 0:32 ` boris.ostrovsky
2021-01-15 5:17 ` Jürgen Groß
2021-01-15 19:46 ` Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 15/21] x86/xen/pvh: Convert indirect jump to retpoline Josh Poimboeuf
2021-01-15 0:33 ` boris.ostrovsky
2021-01-15 5:24 ` Jürgen Groß
2021-01-15 15:08 ` Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 16/21] x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S Josh Poimboeuf
2021-01-14 20:42 ` Steven Rostedt
2021-01-14 19:40 ` [PATCH 17/21] x86/acpi: Convert indirect jump to retpoline Josh Poimboeuf
2021-01-14 22:59 ` Andrew Cooper
2021-01-14 23:47 ` Josh Poimboeuf
2021-01-15 0:54 ` Andrew Cooper
2021-01-14 19:40 ` [PATCH 18/21] x86/acpi: Support objtool validation in wakeup_64.S Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 19/21] x86/power: Convert indirect jumps to retpolines Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 20/21] x86/power: Move restore_registers() to top of the file Josh Poimboeuf
2021-01-14 19:40 ` [PATCH 21/21] x86/power: Support objtool validation in hibernate_asm_64.S Josh Poimboeuf
2021-01-15 0:41 ` [PATCH 00/21] objtool: vmlinux.o and CLANG LTO support Sami Tolvanen
2021-01-15 0:49 ` Nick Desaulniers
2021-01-15 19:52 ` Josh Poimboeuf
2021-01-15 20:19 ` Sedat Dilek
2021-01-15 20:59 ` Josh Poimboeuf
2021-01-15 21:01 ` Sedat Dilek
2021-01-18 17:22 ` Josh Poimboeuf
2021-01-19 21:29 ` Nick Desaulniers
2021-01-20 15:37 ` Josh Poimboeuf
2021-01-15 4:51 ` Sedat Dilek
2021-01-15 5:18 ` Sedat Dilek
2021-01-15 15:30 ` Sedat Dilek
2021-01-15 18:54 ` Sedat Dilek
2021-01-15 19:28 ` Josh Poimboeuf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=86820e8b33d36ee9c28adcf3d2525f0cd05fb0ad.1610652862.git.jpoimboe@redhat.com \
--to=jpoimboe@redhat.com \
--cc=clang-built-linux@googlegroups.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mbenes@suse.cz \
--cc=ndesaulniers@google.com \
--cc=peterz@infradead.org \
--cc=samitolvanen@google.com \
--cc=sedat.dilek@gmail.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).