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stackwalk.c
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stackwalk.c
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// This file is a part of Julia. License is MIT: https://julialang.org/license
/*
stackwalk.c
utilities for walking the stack and looking up information about code addresses
*/
#include <inttypes.h>
#include "julia.h"
#include "julia_internal.h"
#include "threading.h"
#include "julia_assert.h"
// define `jl_unw_get` as a macro, since (like setjmp)
// returning from the callee function will invalidate the context
#ifdef _OS_WINDOWS_
uv_mutex_t jl_in_stackwalk;
#define jl_unw_get(context) (RtlCaptureContext(context), 0)
#elif !defined(JL_DISABLE_LIBUNWIND)
#define jl_unw_get(context) unw_getcontext(context)
#else
int jl_unw_get(void *context) { return -1; }
#endif
#ifdef __cplusplus
extern "C" {
#endif
static int jl_unw_init(bt_cursor_t *cursor, bt_context_t *context) JL_NOTSAFEPOINT;
static int jl_unw_step(bt_cursor_t *cursor, int from_signal_handler, uintptr_t *ip, uintptr_t *sp) JL_NOTSAFEPOINT;
static jl_gcframe_t *is_enter_interpreter_frame(jl_gcframe_t **ppgcstack, uintptr_t sp) JL_NOTSAFEPOINT
{
jl_gcframe_t *pgcstack = *ppgcstack;
while (pgcstack != NULL) {
jl_gcframe_t *prev = pgcstack->prev;
if (pgcstack->nroots & 2) { // tagged frame
uintptr_t frame_fp = ((uintptr_t*)pgcstack)[-1];
if (frame_fp != 0) { // check that frame was fully initialized
if (frame_fp >= sp)
break; // stack grows down, so frame pointer is monotonically increasing
*ppgcstack = prev;
return pgcstack;
}
}
*ppgcstack = pgcstack = prev;
}
return NULL;
}
// Record backtrace entries into bt_data by stepping cursor with jl_unw_step
// until the outermost frame is encountered or the buffer bt_data is (close to)
// full. Returned instruction pointers are adjusted to point to the address of
// the call instruction. The first `skip` frames are not included in `bt_data`.
//
// `maxsize` is the size of the buffer `bt_data` (and `sp` if non-NULL). It
// must be at least `JL_BT_MAX_ENTRY_SIZE + 1` to accommodate extended backtrace
// entries. If `sp != NULL`, the stack pointer corresponding `bt_data[i]` is
// stored in `sp[i]`.
//
// `*ppgcstack` should be given if you want to record extended backtrace
// entries in `bt_data` for each julia interpreter frame.
//
// Flag `from_signal_handler==1` should be set if the cursor was obtained by
// asynchronously interrupting the code.
//
// jl_unw_stepn will return 1 if there are more frames to come. The number of
// elements written to bt_data (and sp if non-NULL) are returned in bt_size.
static int jl_unw_stepn(bt_cursor_t *cursor, jl_bt_element_t *bt_data, size_t *bt_size,
uintptr_t *sp, size_t maxsize, int skip, jl_gcframe_t **ppgcstack,
int from_signal_handler) JL_NOTSAFEPOINT
{
volatile size_t n = 0;
volatile int need_more_space = 0;
uintptr_t return_ip = 0;
uintptr_t thesp = 0;
#if defined(_OS_WINDOWS_) && !defined(_CPU_X86_64_)
uv_mutex_lock(&jl_in_stackwalk);
if (!from_signal_handler) {
// Workaround 32-bit windows bug missing top frame
// See for example https://bugs.chromium.org/p/crashpad/issues/detail?id=53
skip--;
}
#endif
#if !defined(_OS_WINDOWS_)
jl_jmp_buf *old_buf = jl_get_safe_restore();
jl_jmp_buf buf;
jl_set_safe_restore(&buf);
if (!jl_setjmp(buf, 0)) {
#endif
int have_more_frames = 1;
while (have_more_frames) {
if (n + JL_BT_MAX_ENTRY_SIZE + 1 > maxsize) {
// Postpone advancing the cursor: may need more space
need_more_space = 1;
break;
}
uintptr_t oldsp = thesp;
have_more_frames = jl_unw_step(cursor, from_signal_handler, &return_ip, &thesp);
if (oldsp >= thesp && !jl_running_under_rr(0)) {
// The stack pointer is clearly bad, as it must grow downwards.
// But sometimes the external unwinder doesn't check that.
have_more_frames = 0;
}
if (return_ip == 0) {
// The return address is clearly wrong, and while the unwinder
// might try to continue (by popping another stack frame), that
// likely won't work well, and it'll confuse the stack frame
// separator detection logic (double-NULL).
have_more_frames = 0;
}
if (skip > 0) {
skip--;
from_signal_handler = 0;
continue;
}
// For the purposes of looking up debug info for functions, we want
// to harvest addresses for the *call* instruction `call_ip` during
// stack walking. However, this information isn't directly
// available. Instead, the stack walk discovers the address
// `return_ip` which would be *returned to* as the stack is
// unwound.
//
// To infer `call_ip` in full generality we need to understand each
// platform ABI instruction pointer encoding and calling
// conventions, noting that the latter may vary per stack frame.
//
// See also:
// * The LLVM unwinder functions step() and setInfoBasedOnIPRegister()
// https://github.com/llvm/llvm-project/blob/master/libunwind/src/UnwindCursor.hpp
// * The way that libunwind handles it in `unw_get_proc_name`:
// https://lists.nongnu.org/archive/html/libunwind-devel/2014-06/msg00025.html
uintptr_t call_ip = return_ip;
// ARM instruction pointer encoding uses the low bit as a flag for
// thumb mode, which must be cleared before further use. (Note not
// needed for ARM AArch64.) See
// https://github.com/libunwind/libunwind/pull/131
#ifdef _CPU_ARM_
call_ip &= ~(uintptr_t)0x1;
#endif
// Now there's two main cases to adjust for:
// * Normal stack frames where compilers emit a `call` instruction
// which we can get from the return address via `call_ip = return_ip - 1`.
// * Code which was interrupted asynchronously (eg, via a signal)
// is expected to have `call_ip == return_ip`.
if (!from_signal_handler)
call_ip -= 1; // normal frame
from_signal_handler = 0;
if (call_ip == JL_BT_NON_PTR_ENTRY || call_ip == 0) {
// Never leave special marker in the bt data as it can corrupt the GC.
have_more_frames = 0;
call_ip = 0;
}
jl_bt_element_t *bt_entry = bt_data + n;
jl_gcframe_t *pgcstack;
if ((pgcstack = is_enter_interpreter_frame(ppgcstack, thesp))) {
size_t add = jl_capture_interp_frame(bt_entry, (void*)((char*)pgcstack - sizeof(void*)), maxsize - n);
n += add;
bt_entry += add;
while ((pgcstack = is_enter_interpreter_frame(ppgcstack, thesp))) {
// If the compiler got inlining-happy, or the user tried to
// push multiple frames (or the unwinder got very
// confused), we could end up here. That doesn't happen
// now, so just ignore this possibility. If we want this,
// we can work on adding support for it later.
}
}
bt_entry->uintptr = call_ip;
if (sp)
sp[n] = thesp;
n++;
}
// NOTE: if we have some pgcstack entries remaining (because the
// unwinder failed and returned !have_more_frames early), we could
// consider still appending those frames here
#if !defined(_OS_WINDOWS_)
}
else {
// The unwinding fails likely because a invalid memory read.
// Back off one frame since it is likely invalid.
// This seems to be good enough on x86 to make the LLVM debug info
// reader happy.
if (n > 0) n -= 1;
}
jl_set_safe_restore(old_buf);
#endif
#if defined(_OS_WINDOWS_) && !defined(_CPU_X86_64_)
uv_mutex_unlock(&jl_in_stackwalk);
#endif
*bt_size = n;
return need_more_space;
}
NOINLINE size_t rec_backtrace_ctx(jl_bt_element_t *bt_data, size_t maxsize,
bt_context_t *context, jl_gcframe_t *pgcstack) JL_NOTSAFEPOINT
{
bt_cursor_t cursor;
if (!jl_unw_init(&cursor, context))
return 0;
size_t bt_size = 0;
jl_unw_stepn(&cursor, bt_data, &bt_size, NULL, maxsize, 0, &pgcstack, 1);
return bt_size;
}
// Record backtrace into buffer `bt_data`, using a maximum of `maxsize`
// elements, and returning the number of elements written.
//
// The first `skip` frames are omitted, in addition to omitting the frame from
// `rec_backtrace` itself.
NOINLINE size_t rec_backtrace(jl_bt_element_t *bt_data, size_t maxsize, int skip)
{
bt_context_t context;
memset(&context, 0, sizeof(context));
int r = jl_unw_get(&context);
if (r < 0)
return 0;
bt_cursor_t cursor;
if (!jl_unw_init(&cursor, &context) || maxsize == 0)
return 0;
jl_gcframe_t *pgcstack = jl_pgcstack;
size_t bt_size = 0;
jl_unw_stepn(&cursor, bt_data, &bt_size, NULL, maxsize, skip + 1, &pgcstack, 0);
return bt_size;
}
static jl_value_t *array_ptr_void_type JL_ALWAYS_LEAFTYPE = NULL;
// Return backtrace information as an svec of (bt1, bt2, [sp])
//
// The stack pointers `sp` are returned only when `returnsp` evaluates to true.
// bt1 contains raw backtrace entries, while bt2 exists to root any julia
// objects associated with the entries in bt1.
//
// The frame from jl_backtrace_from_here will be skipped; set `skip > 0` to
// skip additional native frames from the start of the backtrace.
JL_DLLEXPORT jl_value_t *jl_backtrace_from_here(int returnsp, int skip)
{
jl_array_t *ip = NULL;
jl_array_t *sp = NULL;
jl_array_t *bt2 = NULL;
JL_GC_PUSH3(&ip, &sp, &bt2);
if (array_ptr_void_type == NULL) {
array_ptr_void_type = jl_apply_type2((jl_value_t*)jl_array_type, (jl_value_t*)jl_voidpointer_type, jl_box_long(1));
}
ip = jl_alloc_array_1d(array_ptr_void_type, 0);
sp = returnsp ? jl_alloc_array_1d(array_ptr_void_type, 0) : NULL;
bt2 = jl_alloc_array_1d(jl_array_any_type, 0);
const size_t maxincr = 1000;
bt_context_t context;
bt_cursor_t cursor;
memset(&context, 0, sizeof(context));
int r = jl_unw_get(&context);
jl_gcframe_t *pgcstack = jl_pgcstack;
if (r == 0 && jl_unw_init(&cursor, &context)) {
// Skip frame for jl_backtrace_from_here itself
skip += 1;
size_t offset = 0;
int have_more_frames = 1;
while (have_more_frames) {
jl_array_grow_end(ip, maxincr);
uintptr_t *sp_ptr = NULL;
if (returnsp) {
jl_array_grow_end(sp, maxincr);
sp_ptr = (uintptr_t*)jl_array_data(sp) + offset;
}
size_t size_incr = 0;
have_more_frames = jl_unw_stepn(&cursor, (jl_bt_element_t*)jl_array_data(ip) + offset,
&size_incr, sp_ptr, maxincr, skip, &pgcstack, 0);
skip = 0;
offset += size_incr;
}
jl_array_del_end(ip, jl_array_len(ip) - offset);
if (returnsp)
jl_array_del_end(sp, jl_array_len(sp) - offset);
size_t n = 0;
jl_bt_element_t *bt_data = (jl_bt_element_t*)jl_array_data(ip);
while (n < jl_array_len(ip)) {
jl_bt_element_t *bt_entry = bt_data + n;
if (!jl_bt_is_native(bt_entry)) {
size_t njlvals = jl_bt_num_jlvals(bt_entry);
for (size_t j = 0; j < njlvals; j++) {
jl_value_t *v = jl_bt_entry_jlvalue(bt_entry, j);
JL_GC_PROMISE_ROOTED(v);
jl_array_ptr_1d_push(bt2, v);
}
}
n += jl_bt_entry_size(bt_entry);
}
}
jl_value_t *bt = returnsp ? (jl_value_t*)jl_svec(3, ip, bt2, sp) : (jl_value_t*)jl_svec(2, ip, bt2);
JL_GC_POP();
return bt;
}
static void decode_backtrace(jl_bt_element_t *bt_data, size_t bt_size,
jl_array_t **btout JL_REQUIRE_ROOTED_SLOT,
jl_array_t **bt2out JL_REQUIRE_ROOTED_SLOT)
{
jl_array_t *bt, *bt2;
if (array_ptr_void_type == NULL) {
array_ptr_void_type = jl_apply_type2((jl_value_t*)jl_array_type, (jl_value_t*)jl_voidpointer_type, jl_box_long(1));
}
bt = *btout = jl_alloc_array_1d(array_ptr_void_type, bt_size);
static_assert(sizeof(jl_bt_element_t) == sizeof(void*),
"jl_bt_element_t is presented as Ptr{Cvoid} on julia side");
memcpy(bt->data, bt_data, bt_size * sizeof(jl_bt_element_t));
bt2 = *bt2out = jl_alloc_array_1d(jl_array_any_type, 0);
// Scan the backtrace buffer for any gc-managed values
for (size_t i = 0; i < bt_size; i += jl_bt_entry_size(bt_data + i)) {
jl_bt_element_t* bt_entry = bt_data + i;
if (jl_bt_is_native(bt_entry))
continue;
size_t njlvals = jl_bt_num_jlvals(bt_entry);
for (size_t j = 0; j < njlvals; j++) {
jl_value_t *v = jl_bt_entry_jlvalue(bt_entry, j);
JL_GC_PROMISE_ROOTED(v);
jl_array_ptr_1d_push(bt2, v);
}
}
}
JL_DLLEXPORT jl_value_t *jl_get_backtrace(void)
{
JL_TIMING(STACKWALK, STACKWALK_Backtrace);
jl_excstack_t *s = jl_current_task->excstack;
jl_bt_element_t *bt_data = NULL;
size_t bt_size = 0;
if (s && s->top) {
bt_data = jl_excstack_bt_data(s, s->top);
bt_size = jl_excstack_bt_size(s, s->top);
}
jl_array_t *bt = NULL, *bt2 = NULL;
JL_GC_PUSH2(&bt, &bt2);
decode_backtrace(bt_data, bt_size, &bt, &bt2);
jl_svec_t *pair = jl_svec2(bt, bt2);
JL_GC_POP();
return (jl_value_t*)pair;
}
// Return data from the exception stack for `task` as an array of Any, starting
// with the top of the stack and returning up to `max_entries`. If requested by
// setting the `include_bt` flag, backtrace data in bt,bt2 format is
// interleaved.
JL_DLLEXPORT jl_value_t *jl_get_excstack(jl_task_t* task, int include_bt, int max_entries)
{
JL_TYPECHK(current_exceptions, task, (jl_value_t*)task);
JL_TIMING(STACKWALK, STACKWALK_Excstack);
jl_task_t *ct = jl_current_task;
if (task != ct && jl_atomic_load_relaxed(&task->_state) == JL_TASK_STATE_RUNNABLE) {
jl_error("Inspecting the exception stack of a task which might "
"be running concurrently isn't allowed.");
}
jl_array_t *stack = NULL;
jl_array_t *bt = NULL;
jl_array_t *bt2 = NULL;
JL_GC_PUSH3(&stack, &bt, &bt2);
stack = jl_alloc_array_1d(jl_array_any_type, 0);
jl_excstack_t *excstack = task->excstack;
size_t itr = excstack ? excstack->top : 0;
int i = 0;
while (itr > 0 && i < max_entries) {
jl_array_ptr_1d_push(stack, jl_excstack_exception(excstack, itr));
if (include_bt) {
decode_backtrace(jl_excstack_bt_data(excstack, itr),
jl_excstack_bt_size(excstack, itr),
&bt, &bt2);
jl_array_ptr_1d_push(stack, (jl_value_t*)bt);
jl_array_ptr_1d_push(stack, (jl_value_t*)bt2);
}
itr = jl_excstack_next(excstack, itr);
i++;
}
JL_GC_POP();
return (jl_value_t*)stack;
}
#if defined(_OS_WINDOWS_)
// XXX: these caches should be per-thread
#ifdef _CPU_X86_64_
static UNWIND_HISTORY_TABLE HistoryTable;
#else
static struct {
DWORD64 dwAddr;
DWORD64 ImageBase;
} HistoryTable;
#endif
static PVOID CALLBACK JuliaFunctionTableAccess64(
_In_ HANDLE hProcess,
_In_ DWORD64 AddrBase)
{
//jl_printf(JL_STDOUT, "lookup %d\n", AddrBase);
#ifdef _CPU_X86_64_
DWORD64 ImageBase;
PRUNTIME_FUNCTION fn = RtlLookupFunctionEntry(AddrBase, &ImageBase, &HistoryTable);
if (fn)
return fn;
uv_mutex_lock(&jl_in_stackwalk);
PVOID ftable = SymFunctionTableAccess64(hProcess, AddrBase);
uv_mutex_unlock(&jl_in_stackwalk);
return ftable;
#else
return SymFunctionTableAccess64(hProcess, AddrBase);
#endif
}
static DWORD64 WINAPI JuliaGetModuleBase64(
_In_ HANDLE hProcess,
_In_ DWORD64 dwAddr)
{
//jl_printf(JL_STDOUT, "lookup base %d\n", dwAddr);
#ifdef _CPU_X86_64_
DWORD64 ImageBase;
PRUNTIME_FUNCTION fn = RtlLookupFunctionEntry(dwAddr, &ImageBase, &HistoryTable);
if (fn)
return ImageBase;
uv_mutex_lock(&jl_in_stackwalk);
DWORD64 fbase = SymGetModuleBase64(hProcess, dwAddr);
uv_mutex_unlock(&jl_in_stackwalk);
return fbase;
#else
if (dwAddr == HistoryTable.dwAddr)
return HistoryTable.ImageBase;
DWORD64 ImageBase = jl_getUnwindInfo(dwAddr);
if (ImageBase) {
HistoryTable.dwAddr = dwAddr;
HistoryTable.ImageBase = ImageBase;
return ImageBase;
}
return SymGetModuleBase64(hProcess, dwAddr);
#endif
}
// Might be called from unmanaged thread.
volatile int needsSymRefreshModuleList;
BOOL (WINAPI *hSymRefreshModuleList)(HANDLE);
JL_DLLEXPORT void jl_refresh_dbg_module_list(void)
{
if (needsSymRefreshModuleList && hSymRefreshModuleList != NULL) {
hSymRefreshModuleList(GetCurrentProcess());
needsSymRefreshModuleList = 0;
}
}
static int jl_unw_init(bt_cursor_t *cursor, bt_context_t *Context)
{
int result;
uv_mutex_lock(&jl_in_stackwalk);
jl_refresh_dbg_module_list();
#if !defined(_CPU_X86_64_)
memset(&cursor->stackframe, 0, sizeof(cursor->stackframe));
cursor->stackframe.AddrPC.Offset = Context->Eip;
cursor->stackframe.AddrStack.Offset = Context->Esp;
cursor->stackframe.AddrFrame.Offset = Context->Ebp;
cursor->stackframe.AddrPC.Mode = AddrModeFlat;
cursor->stackframe.AddrStack.Mode = AddrModeFlat;
cursor->stackframe.AddrFrame.Mode = AddrModeFlat;
cursor->context = *Context;
result = StackWalk64(IMAGE_FILE_MACHINE_I386, GetCurrentProcess(), hMainThread,
&cursor->stackframe, &cursor->context, NULL, JuliaFunctionTableAccess64,
JuliaGetModuleBase64, NULL);
#else
*cursor = *Context;
result = 1;
#endif
uv_mutex_unlock(&jl_in_stackwalk);
return result;
}
static int readable_pointer(LPCVOID pointer)
{
// Check whether the pointer is valid and executable before dereferencing
// to avoid segfault while recording. See #10638.
MEMORY_BASIC_INFORMATION mInfo;
if (VirtualQuery(pointer, &mInfo, sizeof(MEMORY_BASIC_INFORMATION)) == 0)
return 0;
DWORD X = mInfo.AllocationProtect;
if (!((X&PAGE_READONLY) || (X&PAGE_READWRITE) || (X&PAGE_WRITECOPY) || (X&PAGE_EXECUTE_READ)) ||
(X&PAGE_GUARD) || (X&PAGE_NOACCESS))
return 0;
return 1;
}
static int jl_unw_step(bt_cursor_t *cursor, int from_signal_handler, uintptr_t *ip, uintptr_t *sp)
{
// Might be called from unmanaged thread.
#ifndef _CPU_X86_64_
*ip = (uintptr_t)cursor->stackframe.AddrPC.Offset;
*sp = (uintptr_t)cursor->stackframe.AddrStack.Offset;
if (*ip == 0) {
if (!readable_pointer((LPCVOID)*sp))
return 0;
cursor->stackframe.AddrPC.Offset = *(DWORD32*)*sp; // POP EIP (aka RET)
cursor->stackframe.AddrStack.Offset += sizeof(void*);
return cursor->stackframe.AddrPC.Offset != 0;
}
BOOL result = StackWalk64(IMAGE_FILE_MACHINE_I386, GetCurrentProcess(), hMainThread,
&cursor->stackframe, &cursor->context, NULL, JuliaFunctionTableAccess64, JuliaGetModuleBase64, NULL);
return result;
#else
*ip = (uintptr_t)cursor->Rip;
*sp = (uintptr_t)cursor->Rsp;
if (*ip == 0 && from_signal_handler) {
if (!readable_pointer((LPCVOID)*sp))
return 0;
cursor->Rip = *(DWORD64*)*sp; // POP RIP (aka RET)
cursor->Rsp += sizeof(void*);
return cursor->Rip != 0;
}
DWORD64 ImageBase = JuliaGetModuleBase64(GetCurrentProcess(), cursor->Rip - !from_signal_handler);
if (!ImageBase)
return 0;
PRUNTIME_FUNCTION FunctionEntry = (PRUNTIME_FUNCTION)JuliaFunctionTableAccess64(
GetCurrentProcess(), cursor->Rip - !from_signal_handler);
if (!FunctionEntry) {
// Not code or bad unwind?
return 0;
}
else {
PVOID HandlerData;
DWORD64 EstablisherFrame;
(void)RtlVirtualUnwind(
0 /*UNW_FLAG_NHANDLER*/,
ImageBase,
cursor->Rip,
FunctionEntry,
cursor,
&HandlerData,
&EstablisherFrame,
NULL);
}
return cursor->Rip != 0;
#endif
}
#elif !defined(JL_DISABLE_LIBUNWIND)
// stacktrace using libunwind
static int jl_unw_init(bt_cursor_t *cursor, bt_context_t *context)
{
return unw_init_local(cursor, context) == 0;
}
static int jl_unw_step(bt_cursor_t *cursor, int from_signal_handler, uintptr_t *ip, uintptr_t *sp)
{
(void)from_signal_handler; // libunwind also tracks this
unw_word_t reg;
if (unw_get_reg(cursor, UNW_REG_IP, ®) < 0)
return 0;
*ip = reg;
if (unw_get_reg(cursor, UNW_REG_SP, ®) < 0)
return 0;
*sp = reg;
return unw_step(cursor) > 0;
}
#ifdef LLVMLIBUNWIND
NOINLINE size_t rec_backtrace_ctx_dwarf(jl_bt_element_t *bt_data, size_t maxsize,
bt_context_t *context, jl_gcframe_t *pgcstack)
{
size_t bt_size = 0;
bt_cursor_t cursor;
if (unw_init_local_dwarf(&cursor, context) != UNW_ESUCCESS)
return 0;
jl_unw_stepn(&cursor, bt_data, &bt_size, NULL, maxsize, 0, &pgcstack, 1);
return bt_size;
}
#endif
#else
// stacktraces are disabled
static int jl_unw_init(bt_cursor_t *cursor, bt_context_t *context)
{
return 0;
}
static int jl_unw_step(bt_cursor_t *cursor, int from_signal_handler, uintptr_t *ip, uintptr_t *sp)
{
return 0;
}
#endif
JL_DLLEXPORT jl_value_t *jl_lookup_code_address(void *ip, int skipC)
{
jl_task_t *ct = jl_current_task;
jl_frame_t *frames = NULL;
int8_t gc_state = jl_gc_safe_enter(ct->ptls);
int n = jl_getFunctionInfo(&frames, (uintptr_t)ip, skipC, 0);
jl_gc_safe_leave(ct->ptls, gc_state);
jl_value_t *rs = (jl_value_t*)jl_alloc_svec(n);
JL_GC_PUSH1(&rs);
for (int i = 0; i < n; i++) {
jl_frame_t frame = frames[i];
jl_value_t *r = (jl_value_t*)jl_alloc_svec(6);
jl_svecset(rs, i, r);
if (frame.func_name)
jl_svecset(r, 0, jl_symbol(frame.func_name));
else
jl_svecset(r, 0, jl_empty_sym);
free(frame.func_name);
if (frame.file_name)
jl_svecset(r, 1, jl_symbol(frame.file_name));
else
jl_svecset(r, 1, jl_empty_sym);
free(frame.file_name);
jl_svecset(r, 2, jl_box_long(frame.line));
jl_svecset(r, 3, frame.linfo != NULL ? (jl_value_t*)frame.linfo : jl_nothing);
jl_svecset(r, 4, jl_box_bool(frame.fromC));
jl_svecset(r, 5, jl_box_bool(frame.inlined));
}
free(frames);
JL_GC_POP();
return rs;
}
static void jl_safe_print_codeloc(const char* func_name, const char* file_name,
int line, int inlined) JL_NOTSAFEPOINT
{
const char *inlined_str = inlined ? " [inlined]" : "";
if (line != -1) {
jl_safe_printf("%s at %s:%d%s\n", func_name, file_name, line, inlined_str);
}
else {
jl_safe_printf("%s at %s (unknown line)%s\n", func_name, file_name, inlined_str);
}
}
// Print function, file and line containing native instruction pointer `ip` by
// looking up debug info. Prints multiple such frames when `ip` points to
// inlined code.
void jl_print_native_codeloc(uintptr_t ip) JL_NOTSAFEPOINT
{
// This function is not allowed to reference any TLS variables since
// it can be called from an unmanaged thread on OSX.
// it means calling getFunctionInfo with noInline = 1
jl_frame_t *frames = NULL;
int n = jl_getFunctionInfo(&frames, ip, 0, 0);
int i;
for (i = 0; i < n; i++) {
jl_frame_t frame = frames[i];
if (!frame.func_name) {
jl_safe_printf("unknown function (ip: %p)\n", (void*)ip);
}
else {
jl_safe_print_codeloc(frame.func_name, frame.file_name, frame.line, frame.inlined);
free(frame.func_name);
free(frame.file_name);
}
}
free(frames);
}
// Print code location for backtrace buffer entry at *bt_entry
void jl_print_bt_entry_codeloc(jl_bt_element_t *bt_entry) JL_NOTSAFEPOINT
{
if (jl_bt_is_native(bt_entry)) {
jl_print_native_codeloc(bt_entry[0].uintptr);
}
else if (jl_bt_entry_tag(bt_entry) == JL_BT_INTERP_FRAME_TAG) {
size_t ip = jl_bt_entry_header(bt_entry);
jl_value_t *code = jl_bt_entry_jlvalue(bt_entry, 0);
if (jl_is_method_instance(code)) {
// When interpreting a method instance, need to unwrap to find the code info
code = jl_atomic_load_relaxed(&((jl_method_instance_t*)code)->uninferred);
}
if (jl_is_code_info(code)) {
jl_code_info_t *src = (jl_code_info_t*)code;
// See also the debug info handling in codegen.cpp.
// NB: debuginfoloc is 1-based!
intptr_t debuginfoloc = ((int32_t*)jl_array_data(src->codelocs))[ip];
while (debuginfoloc != 0) {
jl_line_info_node_t *locinfo = (jl_line_info_node_t*)
jl_array_ptr_ref(src->linetable, debuginfoloc - 1);
assert(jl_typetagis(locinfo, jl_lineinfonode_type));
const char *func_name = "Unknown";
jl_value_t *method = locinfo->method;
if (jl_is_method_instance(method))
method = ((jl_method_instance_t*)method)->def.value;
if (jl_is_method(method))
method = (jl_value_t*)((jl_method_t*)method)->name;
if (jl_is_symbol(method))
func_name = jl_symbol_name((jl_sym_t*)method);
jl_safe_print_codeloc(func_name, jl_symbol_name(locinfo->file),
locinfo->line, locinfo->inlined_at);
debuginfoloc = locinfo->inlined_at;
}
}
else {
// If we're using this function something bad has already happened;
// be a bit defensive to avoid crashing while reporting the crash.
jl_safe_printf("No code info - unknown interpreter state!\n");
}
}
else {
jl_safe_printf("Non-native bt entry with tag and header bits 0x%" PRIxPTR "\n",
bt_entry[1].uintptr);
}
}
#ifdef _OS_LINUX_
#if defined(__GLIBC__) && defined(_CPU_AARCH64_)
#define LONG_JMP_SP_ENV_SLOT 13
static uintptr_t julia_longjmp_xor_key;
// GLIBC mangles the function pointers in jmp_buf (used in {set,long}*jmp
// functions) by XORing them with a random key. For AArch64 it is a global
// variable rather than a TCB one (as for x86_64/powerpc). We obtain the key by
// issuing a setjmp and XORing the SP pointer values to derive the key.
static void JuliaInitializeLongjmpXorKey(void)
{
// 1. Call REAL(setjmp), which stores the mangled SP in env.
jmp_buf env;
_setjmp(env);
// 2. Retrieve vanilla/mangled SP.
uintptr_t sp;
asm("mov %0, sp" : "=r" (sp));
uintptr_t mangled_sp = ((uintptr_t*)&env)[LONG_JMP_SP_ENV_SLOT];
// 3. xor SPs to obtain key.
julia_longjmp_xor_key = mangled_sp ^ sp;
}
#endif
JL_UNUSED static uintptr_t ptr_demangle(uintptr_t p) JL_NOTSAFEPOINT
{
#if defined(__GLIBC__)
#if defined(_CPU_X86_)
// from https://github.com/bminor/glibc/blame/master/sysdeps/unix/sysv/linux/i386/sysdep.h
// last changed for GLIBC_2.6 on 2007-02-01
asm(" rorl $9, %0\n"
" xorl %%gs:0x18, %0"
: "=r"(p) : "0"(p) : );
#elif defined(_CPU_X86_64_)
// from https://github.com/bminor/glibc/blame/master/sysdeps/unix/sysv/linux/i386/sysdep.h
asm(" rorq $17, %0\n"
" xorq %%fs:0x30, %0"
: "=r"(p) : "0"(p) : );
#elif defined(_CPU_AARCH64_)
// from https://github.com/bminor/glibc/blame/master/sysdeps/unix/sysv/linux/aarch64/sysdep.h
// We need to use a trick like this (from GCC/LLVM TSAN) to get access to it:
// https://github.com/llvm/llvm-project/commit/daa3ebce283a753f280c549cdb103fbb2972f08e
static pthread_once_t once = PTHREAD_ONCE_INIT;
pthread_once(&once, &JuliaInitializeLongjmpXorKey);
p ^= julia_longjmp_xor_key;
#elif defined(_CPU_ARM_)
// from https://github.com/bminor/glibc/blame/master/sysdeps/unix/sysv/linux/arm/sysdep.h
; // nothing to do
#endif
#endif
return p;
}
#endif
// n.b. musl does not mangle pointers, but intentionally makes that impossible
// to determine (https://www.openwall.com/lists/musl/2013/03/29/13) so we do
// not support musl here.
// n.b. We have not looked at other libc (e.g. ulibc), though they are probably
// often compatible with glibc (perhaps with or without pointer mangling).
#ifdef _OS_DARWIN_
// from https://github.com/apple/darwin-xnu/blame/main/libsyscall/os/tsd.h
#define __TSD_PTR_MUNGE 7
#if defined(__i386__) || defined(__x86_64__)
#if defined(__has_attribute)
#if __has_attribute(address_space)
#define OS_GS_RELATIVE __attribute__((address_space(256)))
#endif
#endif
#ifdef OS_GS_RELATIVE
#define _os_tsd_get_base() ((void * OS_GS_RELATIVE *)0)
#else
__attribute__((always_inline))
static __inline__ void*
_os_tsd_get_direct(unsigned long slot)
{
void *ret;
__asm__("mov %%gs:%1, %0" : "=r" (ret) : "m" (*(void **)(slot * sizeof(void *))));
return ret;
}
#endif
#elif defined(__arm__) || defined(__arm64__)
// Unconditionally defined ptrauth_strip (instead of using the ptrauth.h header)
// since libsystem will likely be compiled with -mbranch-protection, and we currently are not.
// code from https://github.com/llvm/llvm-project/blob/7714e0317520207572168388f22012dd9e152e9e/compiler-rt/lib/sanitizer_common/sanitizer_ptrauth.h
static inline uint64_t ptrauth_strip(uint64_t __value, unsigned int __key) JL_NOTSAFEPOINT {
// On the stack the link register is protected with Pointer
// Authentication Code when compiled with -mbranch-protection.
// Let's strip the PAC unconditionally because xpaclri is in the NOP space,
// so will do nothing when it is not enabled or not available.
uint64_t ret;
asm volatile(
"mov x30, %1\n\t"
"hint #7\n\t" // xpaclri
"mov %0, x30\n\t"
: "=r"(ret)
: "r"(__value)
: "x30");
return ret;
}
__attribute__((always_inline, pure))
static __inline__ void**
_os_tsd_get_base(void) JL_NOTSAFEPOINT
{
#if defined(__arm__)
uintptr_t tsd;
__asm__("mrc p15, 0, %0, c13, c0, 3\n"
"bic %0, %0, #0x3\n" : "=r" (tsd));
/* lower 2-bits contain CPU number */
#elif defined(__arm64__)
uint64_t tsd;
__asm__("mrs %0, TPIDRRO_EL0\n"
"bic %0, %0, #0x7\n" : "=r" (tsd));
/* lower 3-bits contain CPU number */
#endif
return (void**)(uintptr_t)tsd;
}
#define _os_tsd_get_base() _os_tsd_get_base()
#endif
#ifdef _os_tsd_get_base
__attribute__((always_inline))
static __inline__ void*
_os_tsd_get_direct(unsigned long slot) JL_NOTSAFEPOINT
{
return _os_tsd_get_base()[slot];
}
#endif
__attribute__((always_inline, pure))
static __inline__ uintptr_t
_os_ptr_munge_token(void) JL_NOTSAFEPOINT
{
return (uintptr_t)_os_tsd_get_direct(__TSD_PTR_MUNGE);
}
__attribute__((always_inline, pure))
JL_UNUSED static __inline__ uintptr_t
_os_ptr_munge(uintptr_t ptr) JL_NOTSAFEPOINT
{
return ptr ^ _os_ptr_munge_token();
}
#define _OS_PTR_UNMUNGE(_ptr) _os_ptr_munge((uintptr_t)(_ptr))
#endif
extern bt_context_t *jl_to_bt_context(void *sigctx);
static void jl_rec_backtrace(jl_task_t *t) JL_NOTSAFEPOINT
{
jl_task_t *ct = jl_current_task;
jl_ptls_t ptls = ct->ptls;
ptls->bt_size = 0;
if (t == ct) {
ptls->bt_size = rec_backtrace(ptls->bt_data, JL_MAX_BT_SIZE, 0);
return;
}
bt_context_t *context = NULL;
bt_context_t c;
int16_t old = -1;
while (!jl_atomic_cmpswap(&t->tid, &old, ptls->tid) && old != ptls->tid) {
int lockret = jl_lock_stackwalk();
// if this task is already running somewhere, we need to stop the thread it is running on and query its state
if (!jl_thread_suspend_and_get_state(old, 0, &c)) {
jl_unlock_stackwalk(lockret);
return;
}
jl_unlock_stackwalk(lockret);
if (jl_atomic_load_relaxed(&t->tid) == old) {
jl_ptls_t ptls2 = jl_atomic_load_relaxed(&jl_all_tls_states)[old];
if (ptls2->previous_task == t || // we might print the wrong stack here, since we can't know whether we executed the swapcontext yet or not, but it at least avoids trying to access the state inside uc_mcontext which might not be set yet
(ptls2->previous_task == NULL && jl_atomic_load_relaxed(&ptls2->current_task) == t)) { // this case should be always accurate
// use the thread context for the unwind state
context = &c;
}
break;
}
// got the wrong thread stopped, try again
jl_thread_resume(old);
}
if (context == NULL && (!t->copy_stack && t->started && t->stkbuf != NULL)) {
// need to read the context from the task stored state
#if defined(_OS_WINDOWS_)
memset(&c, 0, sizeof(c));
_JUMP_BUFFER *mctx = (_JUMP_BUFFER*)&t->ctx.ctx.uc_mcontext;
#if defined(_CPU_X86_64_)
c.Rbx = mctx->Rbx;
c.Rsp = mctx->Rsp;
c.Rbp = mctx->Rbp;
c.Rsi = mctx->Rsi;
c.Rdi = mctx->Rdi;
c.R12 = mctx->R12;
c.R13 = mctx->R13;
c.R14 = mctx->R14;
c.R15 = mctx->R15;
c.Rip = mctx->Rip;
memcpy(&c.Xmm6, &mctx->Xmm6, 10 * sizeof(mctx->Xmm6)); // Xmm6-Xmm15
#else
c.Eip = mctx->Eip;
c.Esp = mctx->Esp;
c.Ebp = mctx->Ebp;
#endif
context = &c;
#elif defined(JL_HAVE_UNW_CONTEXT)
context = &t->ctx.ctx;
#elif defined(JL_HAVE_UCONTEXT)
context = jl_to_bt_context(&t->ctx.ctx);
#elif defined(JL_HAVE_ASM)
memset(&c, 0, sizeof(c));
#if defined(_OS_LINUX_) && defined(__GLIBC__)
__jmp_buf *mctx = &t->ctx.ctx.uc_mcontext->__jmpbuf;
mcontext_t *mc = &c.uc_mcontext;
#if defined(_CPU_X86_)
// https://github.com/bminor/glibc/blame/master/sysdeps/i386/__longjmp.S
// https://github.com/bminor/glibc/blame/master/sysdeps/i386/jmpbuf-offsets.h
// https://github.com/bminor/musl/blame/master/src/setjmp/i386/longjmp.s
mc->gregs[REG_EBX] = (*mctx)[0];
mc->gregs[REG_ESI] = (*mctx)[1];
mc->gregs[REG_EDI] = (*mctx)[2];
mc->gregs[REG_EBP] = (*mctx)[3];
mc->gregs[REG_ESP] = (*mctx)[4];
mc->gregs[REG_EIP] = (*mctx)[5];
// ifdef PTR_DEMANGLE ?
mc->gregs[REG_ESP] = ptr_demangle(mc->gregs[REG_ESP]);
mc->gregs[REG_EIP] = ptr_demangle(mc->gregs[REG_EIP]);
context = &c;
#elif defined(_CPU_X86_64_)
// https://github.com/bminor/glibc/blame/master/sysdeps/x86_64/__longjmp.S
// https://github.com/bminor/glibc/blame/master/sysdeps/x86_64/jmpbuf-offsets.h
// https://github.com/bminor/musl/blame/master/src/setjmp/x86_64/setjmp.s
mc->gregs[REG_RBX] = (*mctx)[0];
mc->gregs[REG_RBP] = (*mctx)[1];
mc->gregs[REG_R12] = (*mctx)[2];
mc->gregs[REG_R13] = (*mctx)[3];
mc->gregs[REG_R14] = (*mctx)[4];
mc->gregs[REG_R15] = (*mctx)[5];
mc->gregs[REG_RSP] = (*mctx)[6];
mc->gregs[REG_RIP] = (*mctx)[7];
// ifdef PTR_DEMANGLE ?
mc->gregs[REG_RBP] = ptr_demangle(mc->gregs[REG_RBP]);
mc->gregs[REG_RSP] = ptr_demangle(mc->gregs[REG_RSP]);
mc->gregs[REG_RIP] = ptr_demangle(mc->gregs[REG_RIP]);
context = &c;
#elif defined(_CPU_ARM_)
// https://github.com/bminor/glibc/blame/master/sysdeps/arm/__longjmp.S
// https://github.com/bminor/glibc/blame/master/sysdeps/arm/include/bits/setjmp.h
// https://github.com/bminor/musl/blame/master/src/setjmp/arm/longjmp.S
mc->arm_sp = (*mctx)[0];
mc->arm_lr = (*mctx)[1];
mc->arm_r4 = (*mctx)[2]; // aka v1
mc->arm_r5 = (*mctx)[3]; // aka v2
mc->arm_r6 = (*mctx)[4]; // aka v3
mc->arm_r7 = (*mctx)[5]; // aka v4
mc->arm_r8 = (*mctx)[6]; // aka v5
mc->arm_r9 = (*mctx)[7]; // aka v6 aka sb
mc->arm_r10 = (*mctx)[8]; // aka v7 aka sl
mc->arm_fp = (*mctx)[10]; // aka v8 aka r11
// ifdef PTR_DEMANGLE ?
mc->arm_sp = ptr_demangle(mc->arm_sp);
mc->arm_lr = ptr_demangle(mc->arm_lr);
mc->arm_pc = mc->arm_lr;
context = &c;
#elif defined(_CPU_AARCH64_)
// https://github.com/bminor/glibc/blame/master/sysdeps/aarch64/__longjmp.S
// https://github.com/bminor/glibc/blame/master/sysdeps/aarch64/jmpbuf-offsets.h
// https://github.com/bminor/musl/blame/master/src/setjmp/aarch64/longjmp.s
// https://github.com/libunwind/libunwind/blob/ec171c9ba7ea3abb2a1383cee2988a7abd483a1f/src/aarch64/unwind_i.h#L62
unw_fpsimd_context_t *mcfp = (unw_fpsimd_context_t*)&mc->__reserved;
mc->regs[19] = (*mctx)[0];
mc->regs[20] = (*mctx)[1];
mc->regs[21] = (*mctx)[2];
mc->regs[22] = (*mctx)[3];
mc->regs[23] = (*mctx)[4];
mc->regs[24] = (*mctx)[5];
mc->regs[25] = (*mctx)[6];
mc->regs[26] = (*mctx)[7];
mc->regs[27] = (*mctx)[8];
mc->regs[28] = (*mctx)[9];
mc->regs[29] = (*mctx)[10]; // aka fp
mc->regs[30] = (*mctx)[11]; // aka lr
// Yes, they did skip 12 why writing the code originally; and, no, I do not know why.
mc->sp = (*mctx)[13];
mcfp->vregs[7] = (*mctx)[14]; // aka d8
mcfp->vregs[8] = (*mctx)[15]; // aka d9
mcfp->vregs[9] = (*mctx)[16]; // aka d10
mcfp->vregs[10] = (*mctx)[17]; // aka d11
mcfp->vregs[11] = (*mctx)[18]; // aka d12
mcfp->vregs[12] = (*mctx)[19]; // aka d13
mcfp->vregs[13] = (*mctx)[20]; // aka d14
mcfp->vregs[14] = (*mctx)[21]; // aka d15