@@ -68,4 +68,16 @@
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
@@ -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 */
@@ -18,12 +18,41 @@
#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 task_struct *task,
struct stackframe *frame)
{
+ const struct code_range *range;
+ unsigned long pc;
+ int i;
+
if (frame->fp == (unsigned long)task_pt_regs(task)->stackframe) {
/* Final frame; no more unwind, no need to check reliability */
return;
@@ -36,6 +65,32 @@ static void unwind_check_reliability(struct task_struct *task,
*/
if (!__kernel_text_address(frame->pc))
frame->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 = frame->pc;
+ for (i = 0; i < num_sym_code_functions; i++) {
+ range = &sym_code_functions[i];
+ if (pc >= range->start && pc < range->end) {
+ frame->reliable = false;
+ return;
+ }
+ }
}
/*
@@ -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 = .;