mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
409 lines
11 KiB
409 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
#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 bool in_entry_code(unsigned long ip) |
|
{ |
|
char *addr = (char *)ip; |
|
|
|
return addr >= __entry_text_start && addr < __entry_text_end; |
|
} |
|
|
|
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 |
|
|
|
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 + sizeof(*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 = sizeof(*regs); |
|
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; |
|
|
|
/* 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(). 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 |
|
* kernel_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->next_bp) { |
|
next_bp = state->next_bp; |
|
state->next_bp = NULL; |
|
} else 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->task != current) |
|
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); |
|
|
|
/* |
|
* If we crash with IP==0, the last successfully executed instruction |
|
* was probably an indirect function call with a NULL function pointer. |
|
* That means that SP points into the middle of an incomplete frame: |
|
* *SP is a return pointer, and *(SP-sizeof(unsigned long)) is where we |
|
* would have written a frame pointer if we hadn't crashed. |
|
* Pretend that the frame is complete and that BP points to it, but save |
|
* the real BP so that we can use it when looking for the next frame. |
|
*/ |
|
if (regs && regs->ip == 0 && (unsigned long *)regs->sp >= first_frame) { |
|
state->next_bp = bp; |
|
bp = ((unsigned long *)regs->sp) - 1; |
|
} |
|
|
|
/* 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->next_bp == NULL && state->bp < first_frame))) |
|
unwind_next_frame(state); |
|
} |
|
EXPORT_SYMBOL_GPL(__unwind_start);
|
|
|