From: madvenka@linux.microsoft.com
To: mark.rutland@arm.com, broonie@kernel.org, jpoimboe@redhat.com,
ardb@kernel.org, nobuta.keiya@fujitsu.com,
sjitindarsingh@gmail.com, catalin.marinas@arm.com,
will@kernel.org, jmorris@namei.org,
linux-arm-kernel@lists.infradead.org,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
madvenka@linux.microsoft.com
Subject: [PATCH v13 09/11] arm64: Create a list of SYM_CODE functions, check return PC against list
Date: Mon, 17 Jan 2022 08:56:06 -0600 [thread overview]
Message-ID: <20220117145608.6781-10-madvenka@linux.microsoft.com> (raw)
In-Reply-To: <20220117145608.6781-1-madvenka@linux.microsoft.com>
From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
SYM_CODE functions don't follow the usual calling conventions. Check if the
return PC in a stack frame falls in any of these. If it does, consider the
stack trace unreliable.
Define a special section for unreliable functions
=================================================
Define a SYM_CODE_END() macro for arm64 that adds the function address
range to a new section called "sym_code_functions".
Linker file
===========
Include the "sym_code_functions" section under read-only data in
vmlinux.lds.S.
Initialization
==============
Define an early_initcall() to create a sym_code_functions[] array from
the linker data.
Unwinder check
==============
Add a reliability check in unwind_check_reliability() that compares a
return PC with sym_code_functions[]. If there is a match, then return
failure.
Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
---
arch/arm64/include/asm/linkage.h | 12 +++++++
arch/arm64/include/asm/sections.h | 1 +
arch/arm64/kernel/stacktrace.c | 55 +++++++++++++++++++++++++++++++
arch/arm64/kernel/vmlinux.lds.S | 10 ++++++
4 files changed, 78 insertions(+)
diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h
index b77e9b3f5371..a47e7914b289 100644
--- a/arch/arm64/include/asm/linkage.h
+++ b/arch/arm64/include/asm/linkage.h
@@ -63,4 +63,16 @@
SYM_FUNC_END_ALIAS(x); \
SYM_FUNC_END_ALIAS(__pi_##x)
+/*
+ * Record the address range of each SYM_CODE function in a struct code_range
+ * in a special section.
+ */
+#define SYM_CODE_END(name) \
+ SYM_END(name, SYM_T_NONE) ;\
+ 99: ;\
+ .pushsection "sym_code_functions", "aw" ;\
+ .quad name ;\
+ .quad 99b ;\
+ .popsection
+
#endif
diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h
index 152cb35bf9df..ac01189668c5 100644
--- a/arch/arm64/include/asm/sections.h
+++ b/arch/arm64/include/asm/sections.h
@@ -22,5 +22,6 @@ extern char __irqentry_text_start[], __irqentry_text_end[];
extern char __mmuoff_data_start[], __mmuoff_data_end[];
extern char __entry_tramp_text_start[], __entry_tramp_text_end[];
extern char __relocate_new_kernel_start[], __relocate_new_kernel_end[];
+extern char __sym_code_functions_start[], __sym_code_functions_end[];
#endif /* __ASM_SECTIONS_H */
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 3dc0374e83f7..8bfe31cbee46 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -18,11 +18,40 @@
#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
+struct code_range {
+ unsigned long start;
+ unsigned long end;
+};
+
+static struct code_range *sym_code_functions;
+static int num_sym_code_functions;
+
+int __init init_sym_code_functions(void)
+{
+ size_t size = (unsigned long)__sym_code_functions_end -
+ (unsigned long)__sym_code_functions_start;
+
+ sym_code_functions = (struct code_range *)__sym_code_functions_start;
+ /*
+ * Order it so that sym_code_functions is not visible before
+ * num_sym_code_functions.
+ */
+ smp_mb();
+ num_sym_code_functions = size / sizeof(struct code_range);
+
+ return 0;
+}
+early_initcall(init_sym_code_functions);
+
/*
* Check the stack frame for conditions that make further unwinding unreliable.
*/
static void unwind_check_reliability(struct unwind_state *state)
{
+ const struct code_range *range;
+ unsigned long pc;
+ int i;
+
if (state->fp == state->final_fp) {
/* Final frame; no more unwind, no need to check reliability */
return;
@@ -35,6 +64,32 @@ static void unwind_check_reliability(struct unwind_state *state)
*/
if (!__kernel_text_address(state->pc))
state->reliable = false;
+
+ /*
+ * Check the return PC against sym_code_functions[]. If there is a
+ * match, then the consider the stack frame unreliable.
+ *
+ * As SYM_CODE functions don't follow the usual calling conventions,
+ * we assume by default that any SYM_CODE function cannot be unwound
+ * reliably.
+ *
+ * Note that this includes:
+ *
+ * - Exception handlers and entry assembly
+ * - Trampoline assembly (e.g., ftrace, kprobes)
+ * - Hypervisor-related assembly
+ * - Hibernation-related assembly
+ * - CPU start-stop, suspend-resume assembly
+ * - Kernel relocation assembly
+ */
+ pc = state->pc;
+ for (i = 0; i < num_sym_code_functions; i++) {
+ range = &sym_code_functions[i];
+ if (pc >= range->start && pc < range->end) {
+ state->reliable = false;
+ return;
+ }
+ }
}
/*
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 50bab186c49b..6381e75e566e 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -122,6 +122,14 @@ jiffies = jiffies_64;
#define TRAMP_TEXT
#endif
+#define SYM_CODE_FUNCTIONS \
+ . = ALIGN(16); \
+ .symcode : AT(ADDR(.symcode) - LOAD_OFFSET) { \
+ __sym_code_functions_start = .; \
+ KEEP(*(sym_code_functions)) \
+ __sym_code_functions_end = .; \
+ }
+
/*
* The size of the PE/COFF section that covers the kernel image, which
* runs from _stext to _edata, must be a round multiple of the PE/COFF
@@ -209,6 +217,8 @@ SECTIONS
swapper_pg_dir = .;
. += PAGE_SIZE;
+ SYM_CODE_FUNCTIONS
+
. = ALIGN(SEGMENT_ALIGN);
__init_begin = .;
__inittext_begin = .;
--
2.25.1
next prev parent reply other threads:[~2022-01-17 14:57 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <95691cae4f4504f33d0fc9075541b1e7deefe96f>
2022-01-17 14:55 ` [PATCH v13 00/11] arm64: Reorganize the unwinder and implement stack trace reliability checks madvenka
2022-01-17 14:55 ` [PATCH v13 01/11] arm64: Remove NULL task check from unwind_frame() madvenka
2022-01-17 14:55 ` [PATCH v13 02/11] arm64: Rename unwinder functions madvenka
2022-01-17 14:56 ` [PATCH v13 03/11] arm64: Rename stackframe to unwind_state madvenka
2022-01-17 14:56 ` [PATCH v13 04/11] arm64: Split unwind_init() madvenka
2022-02-02 18:44 ` Mark Brown
2022-02-03 0:26 ` Madhavan T. Venkataraman
2022-02-03 0:39 ` Madhavan T. Venkataraman
2022-02-03 11:29 ` Mark Brown
2022-02-15 13:07 ` Mark Rutland
2022-02-15 18:04 ` Madhavan T. Venkataraman
2022-01-17 14:56 ` [PATCH v13 05/11] arm64: Copy the task argument to unwind_state madvenka
2022-02-02 18:45 ` Mark Brown
2022-02-15 13:22 ` Mark Rutland
2022-02-22 16:53 ` Madhavan T. Venkataraman
2022-01-17 14:56 ` [PATCH v13 06/11] arm64: Use stack_trace_consume_fn and rename args to unwind() madvenka
2022-02-02 18:46 ` Mark Brown
2022-02-03 0:34 ` Madhavan T. Venkataraman
2022-02-03 11:30 ` Mark Brown
2022-02-03 14:45 ` Madhavan T. Venkataraman
2022-02-15 13:39 ` Mark Rutland
2022-02-15 18:12 ` Madhavan T. Venkataraman
2022-03-07 16:51 ` Madhavan T. Venkataraman
2022-03-07 17:01 ` Mark Brown
2022-03-08 22:00 ` Madhavan T. Venkataraman
2022-03-09 11:47 ` Mark Brown
2022-03-09 15:34 ` Madhavan T. Venkataraman
2022-03-10 8:33 ` Miroslav Benes
2022-03-10 12:36 ` Madhavan T. Venkataraman
2022-03-16 3:43 ` Josh Poimboeuf
2022-04-08 14:44 ` Mark Rutland
2022-04-08 17:58 ` Mark Rutland
2022-04-10 17:42 ` Madhavan T. Venkataraman
2022-04-10 17:33 ` Madhavan T. Venkataraman
2022-04-10 17:45 ` Madhavan T. Venkataraman
2022-01-17 14:56 ` [PATCH v13 07/11] arm64: Make the unwind loop in unwind() similar to other architectures madvenka
2022-01-17 14:56 ` [PATCH v13 08/11] arm64: Introduce stack trace reliability checks in the unwinder madvenka
2022-01-17 14:56 ` madvenka [this message]
2022-01-17 14:56 ` [PATCH v13 10/11] arm64: Introduce arch_stack_walk_reliable() madvenka
2022-01-17 14:56 ` [PATCH v13 11/11] arm64: Select HAVE_RELIABLE_STACKTRACE madvenka
2022-01-25 5:21 ` nobuta.keiya
2022-01-25 13:43 ` Madhavan T. Venkataraman
2022-01-26 10:20 ` nobuta.keiya
2022-01-26 17:14 ` Madhavan T. Venkataraman
2022-01-27 1:13 ` nobuta.keiya
2022-01-26 17:16 ` Mark Brown
2022-04-07 20:25 ` [RFC PATCH v1 0/9] arm64: livepatch: Use DWARF Call Frame Information for frame pointer validation madvenka
2022-04-07 20:25 ` [RFC PATCH v1 1/9] objtool: Parse DWARF Call Frame Information in object files madvenka
2022-04-07 20:25 ` [RFC PATCH v1 2/9] objtool: Generate DWARF rules and place them in a special section madvenka
2022-04-07 20:25 ` [RFC PATCH v1 3/9] dwarf: Build the kernel with DWARF information madvenka
2022-04-07 20:25 ` [RFC PATCH v1 4/9] dwarf: Implement DWARF rule processing in the kernel madvenka
2022-04-07 20:25 ` [RFC PATCH v1 5/9] dwarf: Implement DWARF support for modules madvenka
2022-04-07 20:25 ` [RFC PATCH v1 6/9] arm64: unwinder: Add a reliability check in the unwinder based on DWARF CFI madvenka
2022-04-07 20:25 ` [RFC PATCH v1 7/9] arm64: dwarf: Implement unwind hints madvenka
2022-04-07 20:25 ` [RFC PATCH v1 8/9] dwarf: Miscellaneous changes required for enabling livepatch madvenka
2022-04-07 20:25 ` [RFC PATCH v1 9/9] dwarf: Enable livepatch for ARM64 madvenka
2022-04-08 0:21 ` [RFC PATCH v1 0/9] arm64: livepatch: Use DWARF Call Frame Information for frame pointer validation Josh Poimboeuf
2022-04-08 11:41 ` Peter Zijlstra
2022-04-11 17:26 ` Madhavan T. Venkataraman
2022-04-11 17:18 ` Madhavan T. Venkataraman
2022-04-12 8:32 ` Chen Zhongjin
2022-04-16 0:56 ` Josh Poimboeuf
2022-04-18 12:28 ` Chen Zhongjin
2022-04-18 16:11 ` Josh Poimboeuf
2022-04-18 18:38 ` Madhavan T. Venkataraman
[not found] ` <844b3ede-eddb-cbe6-80e0-3529e2da2eb6@huawei.com>
2022-04-12 17:27 ` Madhavan T. Venkataraman
2022-04-16 1:07 ` Josh Poimboeuf
2022-04-14 14:11 ` Madhavan T. Venkataraman
2022-04-08 10:55 ` Peter Zijlstra
2022-04-08 11:54 ` Peter Zijlstra
2022-04-08 14:34 ` Josh Poimboeuf
2022-04-10 17:47 ` Madhavan T. Venkataraman
2022-04-11 16:34 ` Josh Poimboeuf
2022-04-08 12:06 ` Peter Zijlstra
2022-04-11 17:35 ` Madhavan T. Venkataraman
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