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// SPDX-License-Identifier: GPL-2.0
/*
* Stack trace management functions
*
* Copyright IBM Corp. 2006
*/
#include <linux/perf_event.h>
#include <linux/stacktrace.h>
#include <linux/uaccess.h>
#include <linux/compat.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
#include <asm/kprobes.h>
#include <asm/ptrace.h>
void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
struct task_struct *task, struct pt_regs *regs)
{
struct unwind_state state;
unsigned long addr;
unwind_for_each_frame(&state, task, regs, 0) {
addr = unwind_get_return_address(&state);
if (!addr || !consume_entry(cookie, addr))
break;
}
}
int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
void *cookie, struct task_struct *task)
{
struct unwind_state state;
unsigned long addr;
unwind_for_each_frame(&state, task, NULL, 0) {
if (state.stack_info.type != STACK_TYPE_TASK)
return -EINVAL;
if (state.regs)
return -EINVAL;
addr = unwind_get_return_address(&state);
if (!addr)
return -EINVAL;
#ifdef CONFIG_RETHOOK
/*
* Mark stacktraces with krethook functions on them
* as unreliable.
*/
if (state.ip == (unsigned long)arch_rethook_trampoline)
return -EINVAL;
#endif
if (!consume_entry(cookie, addr))
return -EINVAL;
}
/* Check for stack corruption */
if (unwind_error(&state))
return -EINVAL;
return 0;
}
static inline bool store_ip(stack_trace_consume_fn consume_entry, void *cookie,
struct perf_callchain_entry_ctx *entry, bool perf,
unsigned long ip)
{
#ifdef CONFIG_PERF_EVENTS
if (perf) {
if (perf_callchain_store(entry, ip))
return false;
return true;
}
#endif
return consume_entry(cookie, ip);
}
static inline bool ip_invalid(unsigned long ip)
{
/*
* Perform some basic checks if an instruction address taken
* from unreliable source is invalid.
*/
if (ip & 1)
return true;
if (ip < mmap_min_addr)
return true;
if (ip >= current->mm->context.asce_limit)
return true;
return false;
}
static inline bool ip_within_vdso(unsigned long ip)
{
return in_range(ip, current->mm->context.vdso_base, vdso_text_size());
}
void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie,
struct perf_callchain_entry_ctx *entry,
const struct pt_regs *regs, bool perf)
{
struct stack_frame_vdso_wrapper __user *sf_vdso;
struct stack_frame_user __user *sf;
unsigned long ip, sp;
bool first = true;
if (is_compat_task())
return;
if (!current->mm)
return;
ip = instruction_pointer(regs);
if (!store_ip(consume_entry, cookie, entry, perf, ip))
return;
sf = (void __user *)user_stack_pointer(regs);
pagefault_disable();
while (1) {
if (__get_user(sp, &sf->back_chain))
break;
/*
* VDSO entry code has a non-standard stack frame layout.
* See VDSO user wrapper code for details.
*/
if (!sp && ip_within_vdso(ip)) {
sf_vdso = (void __user *)sf;
if (__get_user(ip, &sf_vdso->return_address))
break;
sp = (unsigned long)sf + STACK_FRAME_VDSO_OVERHEAD;
sf = (void __user *)sp;
if (__get_user(sp, &sf->back_chain))
break;
} else {
sf = (void __user *)sp;
if (__get_user(ip, &sf->gprs[8]))
break;
}
/* Sanity check: ABI requires SP to be 8 byte aligned. */
if (sp & 0x7)
break;
if (ip_invalid(ip)) {
/*
* If the instruction address is invalid, and this
* is the first stack frame, assume r14 has not
* been written to the stack yet. Otherwise exit.
*/
if (!first)
break;
ip = regs->gprs[14];
if (ip_invalid(ip))
break;
}
if (!store_ip(consume_entry, cookie, entry, perf, ip))
return;
first = false;
}
pagefault_enable();
}
void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
const struct pt_regs *regs)
{
arch_stack_walk_user_common(consume_entry, cookie, NULL, regs, false);
}
unsigned long return_address(unsigned int n)
{
struct unwind_state state;
unsigned long addr;
/* Increment to skip current stack entry */
n++;
unwind_for_each_frame(&state, NULL, NULL, 0) {
addr = unwind_get_return_address(&state);
if (!addr)
break;
if (!n--)
return addr;
}
return 0;
}
EXPORT_SYMBOL_GPL(return_address);
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