* [PATCH V3 RESEND 0/3] Support intra-function call validation
@ 2024-03-27 9:44 Rui Qi
2024-03-27 9:44 ` [PATCH V3 RESEND 1/3] objtool: is_fentry_call() crashes if call has no destination Rui Qi
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Rui Qi @ 2024-03-27 9:44 UTC (permalink / raw
To: bp, mingo, tglx, hpa, jpoimboe, peterz, mbenes, gregkh, stable,
alexandre.chartre
Cc: x86, linux-kernel, sashal, Rui Qi
Since kernel version 5.4.217 LTS, there has been an issue with the kernel live patching feature becoming unavailable.
When compiling the sample code for kernel live patching, the following message is displayed when enabled:
livepatch: klp_check_stack: kworker/u256:6:23490 has an unreliable stack
Reproduction steps:
1.git checkout v5.4.269 -b v5.4.269
2.make defconfig
3. Set CONFIG_LIVEPATCH=y、CONFIG_SAMPLE_LIVEPATCH=m
4. make -j bzImage
5. make samples/livepatch/livepatch-sample.ko
6. qemu-system-x86_64 -kernel arch/x86_64/boot/bzImage -nographic -append "console=ttyS0" -initrd initrd.img -m 1024M
7. insmod livepatch-sample.ko
Kernel live patch cannot complete successfully.
After some debugging, the immediate cause of the patch failure is an error in stack checking. The logs are as follows:
[ 340.974853] livepatch: klp_check_stack: kworker/u256:0:23486 has an unreliable stack
[ 340.974858] livepatch: klp_check_stack: kworker/u256:1:23487 has an unreliable stack
[ 340.974863] livepatch: klp_check_stack: kworker/u256:2:23488 has an unreliable stack
[ 340.974868] livepatch: klp_check_stack: kworker/u256:5:23489 has an unreliable stack
[ 340.974872] livepatch: klp_check_stack: kworker/u256:6:23490 has an unreliable stack
......
BTW,if you use the v5.4.217 tag for testing, make sure to set CONFIG_RETPOLINE = y and CONFIG_LIVEPATCH = y, and other steps are consistent with v5.4.269
After investigation, The problem is strongly related to the commit 8afd1c7da2b0 ("x86/speculation: Change FILL_RETURN_BUFFER to work with objtool"),
which would cause incorrect ORC entries to be generated, and the v5.4.217 version can undo this commit to make kernel livepatch work normally.
It is a back-ported upstream patch with some code adjustments,from the git log, the author also mentioned no intra-function call validation support.
Based on commit 24489321d0cd5339f9c2da01eb8bf2bccbac7956 (Linux 5.4.273), This patchset adds stack validation support for intra-function calls,
allowing the kernel live patching feature to work correctly.
v3 - v2
- fix the compile error in arch/x86/kvm/svm.c, the error message is../arch/x86/include/asm/nospec-branch.h: 313: Error: no such instruction: 'unwind_hint_empty'
v2 - v1
- add the tag "Cc: stable@vger.kernel.org" in the sign-off area for patch x86/speculation: Support intra-function call
- add my own Signed-off to all patches
s
Alexandre Chartre (2):
objtool: is_fentry_call() crashes if call has no destination
objtool: Add support for intra-function calls
Rui Qi (1):
x86/speculation: Support intra-function call validation
arch/x86/include/asm/nospec-branch.h | 7 ++
arch/x86/include/asm/unwind_hints.h | 2 +-
include/linux/frame.h | 11 ++++
.../Documentation/stack-validation.txt | 8 +++
tools/objtool/arch/x86/decode.c | 6 ++
tools/objtool/check.c | 64 +++++++++++++++++--
6 files changed, 92 insertions(+), 6 deletions(-)
--
2.20.1
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH V3 RESEND 1/3] objtool: is_fentry_call() crashes if call has no destination
2024-03-27 9:44 [PATCH V3 RESEND 0/3] Support intra-function call validation Rui Qi
@ 2024-03-27 9:44 ` Rui Qi
2024-03-27 9:44 ` [PATCH V3 RESEND 2/3] objtool: Add support for intra-function calls Rui Qi
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Rui Qi @ 2024-03-27 9:44 UTC (permalink / raw
To: bp, mingo, tglx, hpa, jpoimboe, peterz, mbenes, gregkh, stable,
alexandre.chartre
Cc: x86, linux-kernel, sashal, Rui Qi
From: Alexandre Chartre <alexandre.chartre@oracle.com>
commit 87cf61fe848ca8ddf091548671e168f52e8a718e upstream.
Fix is_fentry_call() so that it works if a call has no destination
set (call_dest). This needs to be done in order to support intra-
function calls.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200414103618.12657-2-alexandre.chartre@oracle.com
Signed-off-by: Rui Qi <qirui.001@bytedance.com>
---
tools/objtool/check.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index dfd67243faac..71a24fd46dbd 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1367,7 +1367,7 @@ static int decode_sections(struct objtool_file *file)
static bool is_fentry_call(struct instruction *insn)
{
- if (insn->type == INSN_CALL &&
+ if (insn->type == INSN_CALL && insn->call_dest &&
insn->call_dest->type == STT_NOTYPE &&
!strcmp(insn->call_dest->name, "__fentry__"))
return true;
--
2.20.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH V3 RESEND 2/3] objtool: Add support for intra-function calls
2024-03-27 9:44 [PATCH V3 RESEND 0/3] Support intra-function call validation Rui Qi
2024-03-27 9:44 ` [PATCH V3 RESEND 1/3] objtool: is_fentry_call() crashes if call has no destination Rui Qi
@ 2024-03-27 9:44 ` Rui Qi
2024-03-27 9:44 ` [PATCH V3 RESEND 3/3] x86/speculation: Support intra-function call validation Rui Qi
2024-03-29 10:16 ` [PATCH V3 RESEND 0/3] " Greg KH
3 siblings, 0 replies; 5+ messages in thread
From: Rui Qi @ 2024-03-27 9:44 UTC (permalink / raw
To: bp, mingo, tglx, hpa, jpoimboe, peterz, mbenes, gregkh, stable,
alexandre.chartre
Cc: x86, linux-kernel, sashal, Rui Qi
From: Alexandre Chartre <alexandre.chartre@oracle.com>
commit 8aa8eb2a8f5b3305a95f39957dd2b715fa668e21 upstream.
Change objtool to support intra-function calls. On x86, an intra-function
call is represented in objtool as a push onto the stack (of the return
address), and a jump to the destination address. That way the stack
information is correctly updated and the call flow is still accurate.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200414103618.12657-4-alexandre.chartre@oracle.com
Signed-off-by: Rui Qi <qirui.001@bytedance.com>
---
include/linux/frame.h | 11 ++++
.../Documentation/stack-validation.txt | 8 +++
tools/objtool/arch/x86/decode.c | 6 ++
tools/objtool/check.c | 62 +++++++++++++++++--
4 files changed, 83 insertions(+), 4 deletions(-)
diff --git a/include/linux/frame.h b/include/linux/frame.h
index 02d3ca2d9598..303cda600e56 100644
--- a/include/linux/frame.h
+++ b/include/linux/frame.h
@@ -15,9 +15,20 @@
static void __used __section(.discard.func_stack_frame_non_standard) \
*__func_stack_frame_non_standard_##func = func
+/*
+ * This macro indicates that the following intra-function call is valid.
+ * Any non-annotated intra-function call will cause objtool to issue a warning.
+ */
+#define ANNOTATE_INTRA_FUNCTION_CALL \
+ 999: \
+ .pushsection .discard.intra_function_calls; \
+ .long 999b; \
+ .popsection;
+
#else /* !CONFIG_STACK_VALIDATION */
#define STACK_FRAME_NON_STANDARD(func)
+#define ANNOTATE_INTRA_FUNCTION_CALL
#endif /* CONFIG_STACK_VALIDATION */
diff --git a/tools/objtool/Documentation/stack-validation.txt b/tools/objtool/Documentation/stack-validation.txt
index de094670050b..ee26bb382b70 100644
--- a/tools/objtool/Documentation/stack-validation.txt
+++ b/tools/objtool/Documentation/stack-validation.txt
@@ -290,6 +290,14 @@ they mean, and suggestions for how to fix them.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646
+11. file.o: warning: unannotated intra-function call
+
+ This warning means that a direct call is done to a destination which
+ is not at the beginning of a function. If this is a legit call, you
+ can remove this warning by putting the ANNOTATE_INTRA_FUNCTION_CALL
+ directive right before the call.
+
+
If the error doesn't seem to make sense, it could be a bug in objtool.
Feel free to ask the objtool maintainer for help.
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index a62e032863a8..c3ff62c085c8 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -437,6 +437,12 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
case 0xe8:
*type = INSN_CALL;
+ /*
+ * For the impact on the stack, a CALL behaves like
+ * a PUSH of an immediate value (the return address).
+ */
+ op->src.type = OP_SRC_CONST;
+ op->dest.type = OP_DEST_PUSH;
break;
case 0xfc:
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 71a24fd46dbd..0fa414869f45 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -645,6 +645,7 @@ static int add_jump_destinations(struct objtool_file *file)
return 0;
}
+
/*
* Find the destination instructions for all calls.
*/
@@ -666,10 +667,7 @@ static int add_call_destinations(struct objtool_file *file)
dest_off);
if (!insn->call_dest && !insn->ignore) {
- WARN_FUNC("unsupported intra-function call",
- insn->sec, insn->offset);
- if (retpoline)
- WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE.");
+ WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset);
return -1;
}
@@ -1291,6 +1289,58 @@ static int read_retpoline_hints(struct objtool_file *file)
return 0;
}
+
+static int read_intra_function_calls(struct objtool_file *file)
+{
+ struct instruction *insn;
+ struct section *sec;
+ struct rela *rela;
+
+ sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
+ if (!sec)
+ return 0;
+
+ list_for_each_entry(rela, &sec->rela_list, list) {
+ unsigned long dest_off;
+
+ if (rela->sym->type != STT_SECTION) {
+ WARN("unexpected relocation symbol type in %s",
+ sec->name);
+ return -1;
+ }
+
+ insn = find_insn(file, rela->sym->sec, rela->addend);
+ if (!insn) {
+ WARN("bad .discard.intra_function_call entry");
+ return -1;
+ }
+
+ if (insn->type != INSN_CALL) {
+ WARN_FUNC("intra_function_call not a direct call",
+ insn->sec, insn->offset);
+ return -1;
+ }
+
+ /*
+ * Treat intra-function CALLs as JMPs, but with a stack_op.
+ * See add_call_destinations(), which strips stack_ops from
+ * normal CALLs.
+ */
+ insn->type = INSN_JUMP_UNCONDITIONAL;
+
+ dest_off = insn->offset + insn->len + insn->immediate;
+ insn->jump_dest = find_insn(file, insn->sec, dest_off);
+ if (!insn->jump_dest) {
+ WARN_FUNC("can't find call dest at %s+0x%lx",
+ insn->sec, insn->offset,
+ insn->sec->name, dest_off);
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
static void mark_rodata(struct objtool_file *file)
{
struct section *sec;
@@ -1346,6 +1396,10 @@ static int decode_sections(struct objtool_file *file)
if (ret)
return ret;
+ ret = read_intra_function_calls(file);
+ if (ret)
+ return ret;
+
ret = add_call_destinations(file);
if (ret)
return ret;
--
2.20.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH V3 RESEND 3/3] x86/speculation: Support intra-function call validation
2024-03-27 9:44 [PATCH V3 RESEND 0/3] Support intra-function call validation Rui Qi
2024-03-27 9:44 ` [PATCH V3 RESEND 1/3] objtool: is_fentry_call() crashes if call has no destination Rui Qi
2024-03-27 9:44 ` [PATCH V3 RESEND 2/3] objtool: Add support for intra-function calls Rui Qi
@ 2024-03-27 9:44 ` Rui Qi
2024-03-29 10:16 ` [PATCH V3 RESEND 0/3] " Greg KH
3 siblings, 0 replies; 5+ messages in thread
From: Rui Qi @ 2024-03-27 9:44 UTC (permalink / raw
To: bp, mingo, tglx, hpa, jpoimboe, peterz, mbenes, gregkh, stable,
alexandre.chartre
Cc: x86, linux-kernel, sashal, Rui Qi
commit 8afd1c7da2b0 ("x86/speculation: Change FILL_RETURN_BUFFER
to work with objtool") does not support intra-function call
stack validation, which causes kernel live patching to fail.
This commit adds support for this, and after testing, the kernel
live patching feature is restored to normal.
Fixes: 8afd1c7da2b0 ("x86/speculation: Change FILL_RETURN_BUFFER to work with objtool")
Cc: <stable@vger.kernel.org> # v5.4.250+
Signed-off-by: Rui Qi <qirui.001@bytedance.com>
---
arch/x86/include/asm/nospec-branch.h | 7 +++++++
arch/x86/include/asm/unwind_hints.h | 2 +-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index c8819358a332..a88135c358c0 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -13,6 +13,8 @@
#include <asm/unwind_hints.h>
#include <asm/percpu.h>
+#include <linux/frame.h>
+#include <asm/unwind_hints.h>
/*
* This should be used immediately before a retpoline alternative. It tells
* objtool where the retpolines are so that it can make sense of the control
@@ -51,14 +53,18 @@
#define __FILL_RETURN_BUFFER(reg, nr, sp) \
mov $(nr/2), reg; \
771: \
+ ANNOTATE_INTRA_FUNCTION_CALL; \
call 772f; \
773: /* speculation trap */ \
+ UNWIND_HINT_EMPTY; \
pause; \
lfence; \
jmp 773b; \
772: \
+ ANNOTATE_INTRA_FUNCTION_CALL; \
call 774f; \
775: /* speculation trap */ \
+ UNWIND_HINT_EMPTY; \
pause; \
lfence; \
jmp 775b; \
@@ -152,6 +158,7 @@
.endm
.macro ISSUE_UNBALANCED_RET_GUARD
+ ANNOTATE_INTRA_FUNCTION_CALL;
call .Lunbalanced_ret_guard_\@
int3
.Lunbalanced_ret_guard_\@:
diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 0bcdb1279361..0fd9a22b2eca 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -101,7 +101,7 @@
".popsection\n\t"
#define UNWIND_HINT_SAVE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_SAVE, 0)
-
+#define UNWIND_HINT_EMPTY
#define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE, 0)
#endif /* __ASSEMBLY__ */
--
2.20.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH V3 RESEND 0/3] Support intra-function call validation
2024-03-27 9:44 [PATCH V3 RESEND 0/3] Support intra-function call validation Rui Qi
` (2 preceding siblings ...)
2024-03-27 9:44 ` [PATCH V3 RESEND 3/3] x86/speculation: Support intra-function call validation Rui Qi
@ 2024-03-29 10:16 ` Greg KH
3 siblings, 0 replies; 5+ messages in thread
From: Greg KH @ 2024-03-29 10:16 UTC (permalink / raw
To: Rui Qi
Cc: bp, mingo, tglx, hpa, jpoimboe, peterz, mbenes, stable,
alexandre.chartre, x86, linux-kernel, sashal
On Wed, Mar 27, 2024 at 05:44:44PM +0800, Rui Qi wrote:
> Since kernel version 5.4.217 LTS, there has been an issue with the kernel live patching feature becoming unavailable.
> When compiling the sample code for kernel live patching, the following message is displayed when enabled:
>
> livepatch: klp_check_stack: kworker/u256:6:23490 has an unreliable stack
>
> Reproduction steps:
> 1.git checkout v5.4.269 -b v5.4.269
> 2.make defconfig
> 3. Set CONFIG_LIVEPATCH=y、CONFIG_SAMPLE_LIVEPATCH=m
> 4. make -j bzImage
> 5. make samples/livepatch/livepatch-sample.ko
> 6. qemu-system-x86_64 -kernel arch/x86_64/boot/bzImage -nographic -append "console=ttyS0" -initrd initrd.img -m 1024M
> 7. insmod livepatch-sample.ko
>
> Kernel live patch cannot complete successfully.
>
> After some debugging, the immediate cause of the patch failure is an error in stack checking. The logs are as follows:
> [ 340.974853] livepatch: klp_check_stack: kworker/u256:0:23486 has an unreliable stack
> [ 340.974858] livepatch: klp_check_stack: kworker/u256:1:23487 has an unreliable stack
> [ 340.974863] livepatch: klp_check_stack: kworker/u256:2:23488 has an unreliable stack
> [ 340.974868] livepatch: klp_check_stack: kworker/u256:5:23489 has an unreliable stack
> [ 340.974872] livepatch: klp_check_stack: kworker/u256:6:23490 has an unreliable stack
> ......
>
> BTW,if you use the v5.4.217 tag for testing, make sure to set CONFIG_RETPOLINE = y and CONFIG_LIVEPATCH = y, and other steps are consistent with v5.4.269
>
> After investigation, The problem is strongly related to the commit 8afd1c7da2b0 ("x86/speculation: Change FILL_RETURN_BUFFER to work with objtool"),
> which would cause incorrect ORC entries to be generated, and the v5.4.217 version can undo this commit to make kernel livepatch work normally.
> It is a back-ported upstream patch with some code adjustments,from the git log, the author also mentioned no intra-function call validation support.
>
> Based on commit 24489321d0cd5339f9c2da01eb8bf2bccbac7956 (Linux 5.4.273), This patchset adds stack validation support for intra-function calls,
> allowing the kernel live patching feature to work correctly.
Sorry for the delay, all now queued up.
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-03-29 10:16 UTC | newest]
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2024-03-27 9:44 [PATCH V3 RESEND 0/3] Support intra-function call validation Rui Qi
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2024-03-27 9:44 ` [PATCH V3 RESEND 2/3] objtool: Add support for intra-function calls Rui Qi
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