void notrace op_mips_backtrace(struct pt_regs *const regs, unsigned int depth)
{
struct stackframe frame = { .sp = regs->regs[29],
.pc = regs->cp0_epc,
.ra = regs->regs[31] };
const int userspace = user_mode(regs);
const unsigned long low_addr = ALIGN(frame.sp, THREAD_SIZE);
if (userspace)
do_user_backtrace(low_addr, &frame, depth);
else
do_kernel_backtrace(low_addr, &frame, depth);
}
static kern_return_t do_kernel_backtrace(
thread_t thread,
struct x86_kernel_state *regs,
uint64_t *frames,
mach_msg_type_number_t *start_idx,
mach_msg_type_number_t max_idx)
{
uint64_t kernStackMin = (uint64_t)thread->kernel_stack;
uint64_t kernStackMax = (uint64_t)kernStackMin + kernel_stack_size;
mach_msg_type_number_t ct = *start_idx;
kern_return_t kr = KERN_FAILURE;
#if __LP64__
uint64_t currPC = 0ULL;
uint64_t currFP = 0ULL;
uint64_t prevPC = 0ULL;
uint64_t prevFP = 0ULL;
if(KERN_SUCCESS != chudxnu_kern_read(&currPC, (vm_offset_t)&(regs->k_rip), sizeof(uint64_t))) {
return KERN_FAILURE;
}
if(KERN_SUCCESS != chudxnu_kern_read(&currFP, (vm_offset_t)&(regs->k_rbp), sizeof(uint64_t))) {
return KERN_FAILURE;
}
#else
uint32_t currPC = 0U;
uint32_t currFP = 0U;
uint32_t prevPC = 0U;
uint32_t prevFP = 0U;
if(KERN_SUCCESS != chudxnu_kern_read(&currPC, (vm_offset_t)&(regs->k_eip), sizeof(uint32_t))) {
return KERN_FAILURE;
}
if(KERN_SUCCESS != chudxnu_kern_read(&currFP, (vm_offset_t)&(regs->k_ebp), sizeof(uint32_t))) {
return KERN_FAILURE;
}
#endif
if(*start_idx >= max_idx)
return KERN_RESOURCE_SHORTAGE; // no frames traced
if(!currPC) {
return KERN_FAILURE;
}
frames[ct++] = (uint64_t)currPC;
// build a backtrace of this kernel state
#if __LP64__
while(VALID_STACK_ADDRESS64(TRUE, currFP, kernStackMin, kernStackMax)) {
// this is the address where caller lives in the user thread
uint64_t caller = currFP + sizeof(uint64_t);
#else
while(VALID_STACK_ADDRESS(TRUE, currFP, kernStackMin, kernStackMax)) {
uint32_t caller = (uint32_t)currFP + sizeof(uint32_t);
#endif
if(!currFP || !currPC) {
currPC = 0;
break;
}
if(ct >= max_idx) {
*start_idx = ct;
return KERN_RESOURCE_SHORTAGE;
}
/* read our caller */
kr = chudxnu_kern_read(&currPC, (vm_offset_t)caller, sizeof(currPC));
if(kr != KERN_SUCCESS || !currPC) {
currPC = 0UL;
break;
}
/*
* retrive contents of the frame pointer and advance to the next stack
* frame if it's valid
*/
prevFP = 0;
kr = chudxnu_kern_read(&prevFP, (vm_offset_t)currFP, sizeof(currPC));
#if __LP64__
if(VALID_STACK_ADDRESS64(TRUE, prevFP, kernStackMin, kernStackMax)) {
#else
if(VALID_STACK_ADDRESS(TRUE, prevFP, kernStackMin, kernStackMax)) {
#endif
frames[ct++] = (uint64_t)currPC;
prevPC = currPC;
}
if(prevFP <= currFP) {
break;
} else {
currFP = prevFP;
}
}
*start_idx = ct;
return KERN_SUCCESS;
}
__private_extern__
kern_return_t chudxnu_thread_get_callstack64(
thread_t thread,
uint64_t *callstack,
mach_msg_type_number_t *count,
boolean_t user_only)
{
kern_return_t kr = KERN_FAILURE;
task_t task = thread->task;
uint64_t currPC = 0ULL;
boolean_t supervisor = FALSE;
mach_msg_type_number_t bufferIndex = 0;
mach_msg_type_number_t bufferMaxIndex = *count;
x86_saved_state_t *tagged_regs = NULL; // kernel register state
x86_saved_state64_t *regs64 = NULL;
x86_saved_state32_t *regs32 = NULL;
x86_saved_state32_t *u_regs32 = NULL;
x86_saved_state64_t *u_regs64 = NULL;
struct x86_kernel_state *kregs = NULL;
if(ml_at_interrupt_context()) {
if(user_only) {
/* can't backtrace user state on interrupt stack. */
return KERN_FAILURE;
}
/* backtracing at interrupt context? */
if(thread == current_thread() && current_cpu_datap()->cpu_int_state) {
/*
* Locate the registers for the interrupted thread, assuming it is
* current_thread().
*/
tagged_regs = current_cpu_datap()->cpu_int_state;
if(is_saved_state64(tagged_regs)) {
/* 64 bit registers */
regs64 = saved_state64(tagged_regs);
supervisor = ((regs64->isf.cs & SEL_PL) != SEL_PL_U);
} else {
/* 32 bit registers */
regs32 = saved_state32(tagged_regs);
supervisor = ((regs32->cs & SEL_PL) != SEL_PL_U);
}
}
}
if(!ml_at_interrupt_context() && kernel_task == task) {
if(!thread->kernel_stack) {
return KERN_FAILURE;
}
// Kernel thread not at interrupt context
kregs = (struct x86_kernel_state *)NULL;
// nofault read of the thread->kernel_stack pointer
if(KERN_SUCCESS != chudxnu_kern_read(&kregs, (vm_offset_t)&(thread->kernel_stack), sizeof(void *))) {
return KERN_FAILURE;
}
// Adjust to find the saved kernel state
kregs = STACK_IKS((vm_offset_t)(uintptr_t)kregs);
supervisor = TRUE;
} else if(!tagged_regs) {
/*
* not at interrupt context, or tracing a different thread than
* current_thread() at interrupt context
*/
tagged_regs = USER_STATE(thread);
if(is_saved_state64(tagged_regs)) {
/* 64 bit registers */
regs64 = saved_state64(tagged_regs);
supervisor = ((regs64->isf.cs & SEL_PL) != SEL_PL_U);
} else {
/* 32 bit registers */
regs32 = saved_state32(tagged_regs);
supervisor = ((regs32->cs & SEL_PL) != SEL_PL_U);
}
}
*count = 0;
if(supervisor) {
// the caller only wants a user callstack.
if(user_only) {
// bail - we've only got kernel state
return KERN_FAILURE;
}
} else {
// regs32(64) is not in supervisor mode.
u_regs32 = regs32;
u_regs64 = regs64;
regs32 = NULL;
regs64 = NULL;
}
if (user_only) {
/* we only want to backtrace the user mode */
if(!(u_regs32 || u_regs64)) {
/* no user state to look at */
return KERN_FAILURE;
}
}
/*
* Order of preference for top of stack:
* 64 bit kernel state (not likely)
* 32 bit kernel state
* 64 bit user land state
* 32 bit user land state
*/
if(kregs) {
/*
* nofault read of the registers from the kernel stack (as they can
* disappear on the fly).
*/
#if __LP64__
if(KERN_SUCCESS != chudxnu_kern_read(&currPC, (vm_offset_t)&(kregs->k_rip), sizeof(uint64_t))) {
return KERN_FAILURE;
}
#else
uint32_t tmp;
if(KERN_SUCCESS != chudxnu_kern_read(&tmp, (vm_offset_t)&(kregs->k_eip), sizeof(uint32_t))) {
return KERN_FAILURE;
}
currPC = (uint64_t)tmp;
#endif
} else if(regs64) {
currPC = regs64->isf.rip;
} else if(regs32) {
currPC = (uint64_t) regs32->eip;
} else if(u_regs64) {
currPC = u_regs64->isf.rip;
} else if(u_regs32) {
currPC = (uint64_t) u_regs32->eip;
}
if(!currPC) {
/* no top of the stack, bail out */
return KERN_FAILURE;
}
bufferIndex = 0;
if(bufferMaxIndex < 1) {
*count = 0;
return KERN_RESOURCE_SHORTAGE;
}
/* backtrace kernel */
if(kregs) {
addr64_t address = 0ULL;
size_t size = 0UL;
// do the backtrace
kr = do_kernel_backtrace(thread, kregs, callstack, &bufferIndex, bufferMaxIndex);
// and do a nofault read of (r|e)sp
#if __LP64__
uint64_t rsp = 0ULL;
size = sizeof(uint64_t);
if(KERN_SUCCESS != chudxnu_kern_read(&address, (vm_offset_t)&(kregs->k_rsp), size)) {
address = 0ULL;
}
#else
uint32_t rsp = 0ULL, tmp = 0ULL;
size = sizeof(uint32_t);
if(KERN_SUCCESS != chudxnu_kern_read(&tmp, (vm_offset_t)&(kregs->k_esp), size)) {
address = 0ULL;
} else {
address = (addr64_t)tmp;
}
#endif
if(address && KERN_SUCCESS == chudxnu_kern_read(&rsp, (vm_offset_t)address, size) && bufferIndex < bufferMaxIndex) {
callstack[bufferIndex++] = (uint64_t)rsp;
}
} else if(regs64) {
uint64_t rsp = 0ULL;
// backtrace the 64bit side.
kr = do_backtrace64(task, thread, regs64, callstack, &bufferIndex,
bufferMaxIndex, TRUE);
if(KERN_SUCCESS == chudxnu_kern_read(&rsp, (vm_offset_t) regs64->isf.rsp, sizeof(uint64_t)) &&
bufferIndex < bufferMaxIndex) {
callstack[bufferIndex++] = rsp;
}
} else if(regs32) {
uint32_t esp = 0UL;
// backtrace the 32bit side.
kr = do_backtrace32(task, thread, regs32, callstack, &bufferIndex,
bufferMaxIndex, TRUE);
if(KERN_SUCCESS == chudxnu_kern_read(&esp, (vm_offset_t) regs32->uesp, sizeof(uint32_t)) &&
bufferIndex < bufferMaxIndex) {
callstack[bufferIndex++] = (uint64_t) esp;
}
} else if(u_regs64) {
/* backtrace user land */
uint64_t rsp = 0ULL;
kr = do_backtrace64(task, thread, u_regs64, callstack, &bufferIndex,
bufferMaxIndex, FALSE);
if(KERN_SUCCESS == chudxnu_task_read(task, &rsp, (addr64_t) u_regs64->isf.rsp, sizeof(uint64_t)) &&
bufferIndex < bufferMaxIndex) {
callstack[bufferIndex++] = rsp;
}
} else if(u_regs32) {
uint32_t esp = 0UL;
kr = do_backtrace32(task, thread, u_regs32, callstack, &bufferIndex,
bufferMaxIndex, FALSE);
if(KERN_SUCCESS == chudxnu_task_read(task, &esp, (addr64_t) u_regs32->uesp, sizeof(uint32_t)) &&
bufferIndex < bufferMaxIndex) {
callstack[bufferIndex++] = (uint64_t) esp;
}
}
*count = bufferIndex;
return kr;
}
