v4.19.13 snapshot.
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
new file mode 100644
index 0000000..3dc26f9
--- /dev/null
+++ b/arch/x86/kernel/unwind_frame.c
@@ -0,0 +1,416 @@
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
+#include <linux/interrupt.h>
+#include <asm/sections.h>
+#include <asm/ptrace.h>
+#include <asm/bitops.h>
+#include <asm/stacktrace.h>
+#include <asm/unwind.h>
+
+#define FRAME_HEADER_SIZE (sizeof(long) * 2)
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+ if (unwind_done(state))
+ return 0;
+
+ return __kernel_text_address(state->ip) ? state->ip : 0;
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
+{
+ if (unwind_done(state))
+ return NULL;
+
+ return state->regs ? &state->regs->ip : state->bp + 1;
+}
+
+static void unwind_dump(struct unwind_state *state)
+{
+ static bool dumped_before = false;
+ bool prev_zero, zero = false;
+ unsigned long word, *sp;
+ struct stack_info stack_info = {0};
+ unsigned long visit_mask = 0;
+
+ if (dumped_before)
+ return;
+
+ dumped_before = true;
+
+ printk_deferred("unwind stack type:%d next_sp:%p mask:0x%lx graph_idx:%d\n",
+ state->stack_info.type, state->stack_info.next_sp,
+ state->stack_mask, state->graph_idx);
+
+ for (sp = PTR_ALIGN(state->orig_sp, sizeof(long)); sp;
+ sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
+ if (get_stack_info(sp, state->task, &stack_info, &visit_mask))
+ break;
+
+ for (; sp < stack_info.end; sp++) {
+
+ word = READ_ONCE_NOCHECK(*sp);
+
+ prev_zero = zero;
+ zero = word == 0;
+
+ if (zero) {
+ if (!prev_zero)
+ printk_deferred("%p: %0*x ...\n",
+ sp, BITS_PER_LONG/4, 0);
+ continue;
+ }
+
+ printk_deferred("%p: %0*lx (%pB)\n",
+ sp, BITS_PER_LONG/4, word, (void *)word);
+ }
+ }
+}
+
+static size_t regs_size(struct pt_regs *regs)
+{
+ /* x86_32 regs from kernel mode are two words shorter: */
+ if (IS_ENABLED(CONFIG_X86_32) && !user_mode(regs))
+ return sizeof(*regs) - 2*sizeof(long);
+
+ return sizeof(*regs);
+}
+
+static bool in_entry_code(unsigned long ip)
+{
+ char *addr = (char *)ip;
+
+ if (addr >= __entry_text_start && addr < __entry_text_end)
+ return true;
+
+ if (addr >= __irqentry_text_start && addr < __irqentry_text_end)
+ return true;
+
+ return false;
+}
+
+static inline unsigned long *last_frame(struct unwind_state *state)
+{
+ return (unsigned long *)task_pt_regs(state->task) - 2;
+}
+
+static bool is_last_frame(struct unwind_state *state)
+{
+ return state->bp == last_frame(state);
+}
+
+#ifdef CONFIG_X86_32
+#define GCC_REALIGN_WORDS 3
+#else
+#define GCC_REALIGN_WORDS 1
+#endif
+
+static inline unsigned long *last_aligned_frame(struct unwind_state *state)
+{
+ return last_frame(state) - GCC_REALIGN_WORDS;
+}
+
+static bool is_last_aligned_frame(struct unwind_state *state)
+{
+ unsigned long *last_bp = last_frame(state);
+ unsigned long *aligned_bp = last_aligned_frame(state);
+
+ /*
+ * GCC can occasionally decide to realign the stack pointer and change
+ * the offset of the stack frame in the prologue of a function called
+ * by head/entry code. Examples:
+ *
+ * <start_secondary>:
+ * push %edi
+ * lea 0x8(%esp),%edi
+ * and $0xfffffff8,%esp
+ * pushl -0x4(%edi)
+ * push %ebp
+ * mov %esp,%ebp
+ *
+ * <x86_64_start_kernel>:
+ * lea 0x8(%rsp),%r10
+ * and $0xfffffffffffffff0,%rsp
+ * pushq -0x8(%r10)
+ * push %rbp
+ * mov %rsp,%rbp
+ *
+ * After aligning the stack, it pushes a duplicate copy of the return
+ * address before pushing the frame pointer.
+ */
+ return (state->bp == aligned_bp && *(aligned_bp + 1) == *(last_bp + 1));
+}
+
+static bool is_last_ftrace_frame(struct unwind_state *state)
+{
+ unsigned long *last_bp = last_frame(state);
+ unsigned long *last_ftrace_bp = last_bp - 3;
+
+ /*
+ * When unwinding from an ftrace handler of a function called by entry
+ * code, the stack layout of the last frame is:
+ *
+ * bp
+ * parent ret addr
+ * bp
+ * function ret addr
+ * parent ret addr
+ * pt_regs
+ * -----------------
+ */
+ return (state->bp == last_ftrace_bp &&
+ *state->bp == *(state->bp + 2) &&
+ *(state->bp + 1) == *(state->bp + 4));
+}
+
+static bool is_last_task_frame(struct unwind_state *state)
+{
+ return is_last_frame(state) || is_last_aligned_frame(state) ||
+ is_last_ftrace_frame(state);
+}
+
+/*
+ * This determines if the frame pointer actually contains an encoded pointer to
+ * pt_regs on the stack. See ENCODE_FRAME_POINTER.
+ */
+#ifdef CONFIG_X86_64
+static struct pt_regs *decode_frame_pointer(unsigned long *bp)
+{
+ unsigned long regs = (unsigned long)bp;
+
+ if (!(regs & 0x1))
+ return NULL;
+
+ return (struct pt_regs *)(regs & ~0x1);
+}
+#else
+static struct pt_regs *decode_frame_pointer(unsigned long *bp)
+{
+ unsigned long regs = (unsigned long)bp;
+
+ if (regs & 0x80000000)
+ return NULL;
+
+ return (struct pt_regs *)(regs | 0x80000000);
+}
+#endif
+
+#ifdef CONFIG_X86_32
+#define KERNEL_REGS_SIZE (sizeof(struct pt_regs) - 2*sizeof(long))
+#else
+#define KERNEL_REGS_SIZE (sizeof(struct pt_regs))
+#endif
+
+static bool update_stack_state(struct unwind_state *state,
+ unsigned long *next_bp)
+{
+ struct stack_info *info = &state->stack_info;
+ enum stack_type prev_type = info->type;
+ struct pt_regs *regs;
+ unsigned long *frame, *prev_frame_end, *addr_p, addr;
+ size_t len;
+
+ if (state->regs)
+ prev_frame_end = (void *)state->regs + regs_size(state->regs);
+ else
+ prev_frame_end = (void *)state->bp + FRAME_HEADER_SIZE;
+
+ /* Is the next frame pointer an encoded pointer to pt_regs? */
+ regs = decode_frame_pointer(next_bp);
+ if (regs) {
+ frame = (unsigned long *)regs;
+ len = KERNEL_REGS_SIZE;
+ state->got_irq = true;
+ } else {
+ frame = next_bp;
+ len = FRAME_HEADER_SIZE;
+ }
+
+ /*
+ * If the next bp isn't on the current stack, switch to the next one.
+ *
+ * We may have to traverse multiple stacks to deal with the possibility
+ * that info->next_sp could point to an empty stack and the next bp
+ * could be on a subsequent stack.
+ */
+ while (!on_stack(info, frame, len))
+ if (get_stack_info(info->next_sp, state->task, info,
+ &state->stack_mask))
+ return false;
+
+ /* Make sure it only unwinds up and doesn't overlap the prev frame: */
+ if (state->orig_sp && state->stack_info.type == prev_type &&
+ frame < prev_frame_end)
+ return false;
+
+ /*
+ * On 32-bit with user mode regs, make sure the last two regs are safe
+ * to access:
+ */
+ if (IS_ENABLED(CONFIG_X86_32) && regs && user_mode(regs) &&
+ !on_stack(info, frame, len + 2*sizeof(long)))
+ return false;
+
+ /* Move state to the next frame: */
+ if (regs) {
+ state->regs = regs;
+ state->bp = NULL;
+ } else {
+ state->bp = next_bp;
+ state->regs = NULL;
+ }
+
+ /* Save the return address: */
+ if (state->regs && user_mode(state->regs))
+ state->ip = 0;
+ else {
+ addr_p = unwind_get_return_address_ptr(state);
+ addr = READ_ONCE_TASK_STACK(state->task, *addr_p);
+ state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
+ addr, addr_p);
+ }
+
+ /* Save the original stack pointer for unwind_dump(): */
+ if (!state->orig_sp)
+ state->orig_sp = frame;
+
+ return true;
+}
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+ struct pt_regs *regs;
+ unsigned long *next_bp;
+
+ if (unwind_done(state))
+ return false;
+
+ /* Have we reached the end? */
+ if (state->regs && user_mode(state->regs))
+ goto the_end;
+
+ if (is_last_task_frame(state)) {
+ regs = task_pt_regs(state->task);
+
+ /*
+ * kthreads (other than the boot CPU's idle thread) have some
+ * partial regs at the end of their stack which were placed
+ * there by copy_thread_tls(). But the regs don't have any
+ * useful information, so we can skip them.
+ *
+ * This user_mode() check is slightly broader than a PF_KTHREAD
+ * check because it also catches the awkward situation where a
+ * newly forked kthread transitions into a user task by calling
+ * do_execve(), which eventually clears PF_KTHREAD.
+ */
+ if (!user_mode(regs))
+ goto the_end;
+
+ /*
+ * We're almost at the end, but not quite: there's still the
+ * syscall regs frame. Entry code doesn't encode the regs
+ * pointer for syscalls, so we have to set it manually.
+ */
+ state->regs = regs;
+ state->bp = NULL;
+ state->ip = 0;
+ return true;
+ }
+
+ /* Get the next frame pointer: */
+ if (state->regs)
+ next_bp = (unsigned long *)state->regs->bp;
+ else
+ next_bp = (unsigned long *)READ_ONCE_TASK_STACK(state->task, *state->bp);
+
+ /* Move to the next frame if it's safe: */
+ if (!update_stack_state(state, next_bp))
+ goto bad_address;
+
+ return true;
+
+bad_address:
+ state->error = true;
+
+ /*
+ * When unwinding a non-current task, the task might actually be
+ * running on another CPU, in which case it could be modifying its
+ * stack while we're reading it. This is generally not a problem and
+ * can be ignored as long as the caller understands that unwinding
+ * another task will not always succeed.
+ */
+ if (state->task != current)
+ goto the_end;
+
+ /*
+ * Don't warn if the unwinder got lost due to an interrupt in entry
+ * code or in the C handler before the first frame pointer got set up:
+ */
+ if (state->got_irq && in_entry_code(state->ip))
+ goto the_end;
+ if (state->regs &&
+ state->regs->sp >= (unsigned long)last_aligned_frame(state) &&
+ state->regs->sp < (unsigned long)task_pt_regs(state->task))
+ goto the_end;
+
+ /*
+ * There are some known frame pointer issues on 32-bit. Disable
+ * unwinder warnings on 32-bit until it gets objtool support.
+ */
+ if (IS_ENABLED(CONFIG_X86_32))
+ goto the_end;
+
+ if (state->regs) {
+ printk_deferred_once(KERN_WARNING
+ "WARNING: kernel stack regs at %p in %s:%d has bad 'bp' value %p\n",
+ state->regs, state->task->comm,
+ state->task->pid, next_bp);
+ unwind_dump(state);
+ } else {
+ printk_deferred_once(KERN_WARNING
+ "WARNING: kernel stack frame pointer at %p in %s:%d has bad value %p\n",
+ state->bp, state->task->comm,
+ state->task->pid, next_bp);
+ unwind_dump(state);
+ }
+the_end:
+ state->stack_info.type = STACK_TYPE_UNKNOWN;
+ return false;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);
+
+void __unwind_start(struct unwind_state *state, struct task_struct *task,
+ struct pt_regs *regs, unsigned long *first_frame)
+{
+ unsigned long *bp;
+
+ memset(state, 0, sizeof(*state));
+ state->task = task;
+ state->got_irq = (regs);
+
+ /* Don't even attempt to start from user mode regs: */
+ if (regs && user_mode(regs)) {
+ state->stack_info.type = STACK_TYPE_UNKNOWN;
+ return;
+ }
+
+ bp = get_frame_pointer(task, regs);
+
+ /* Initialize stack info and make sure the frame data is accessible: */
+ get_stack_info(bp, state->task, &state->stack_info,
+ &state->stack_mask);
+ update_stack_state(state, bp);
+
+ /*
+ * The caller can provide the address of the first frame directly
+ * (first_frame) or indirectly (regs->sp) to indicate which stack frame
+ * to start unwinding at. Skip ahead until we reach it.
+ */
+ while (!unwind_done(state) &&
+ (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
+ state->bp < first_frame))
+ unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(__unwind_start);