cae74ba8c2
Using __builtin_return_address(n) might return undefined values when used with values of n outside of the stack. This was noticed when __builtin_return_address() was called in ftrace on top level functions like the interrupt handlers. As this behaviour cannot be fixed, use the s390 stack unwinder and remove the ftrace compilation flags for unwind_bc.c and stacktrace.c to prevent the unwinding function polluting function traces. Another advantage is that this also works with clang. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
123 lines
2.6 KiB
C
123 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Stack trace management functions
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*
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* Copyright IBM Corp. 2006
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*/
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#include <linux/stacktrace.h>
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#include <linux/uaccess.h>
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#include <linux/compat.h>
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#include <asm/stacktrace.h>
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#include <asm/unwind.h>
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#include <asm/kprobes.h>
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#include <asm/ptrace.h>
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void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
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struct task_struct *task, struct pt_regs *regs)
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{
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struct unwind_state state;
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unsigned long addr;
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unwind_for_each_frame(&state, task, regs, 0) {
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addr = unwind_get_return_address(&state);
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if (!addr || !consume_entry(cookie, addr))
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break;
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}
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}
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int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
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void *cookie, struct task_struct *task)
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{
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struct unwind_state state;
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unsigned long addr;
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unwind_for_each_frame(&state, task, NULL, 0) {
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if (state.stack_info.type != STACK_TYPE_TASK)
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return -EINVAL;
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if (state.regs)
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return -EINVAL;
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addr = unwind_get_return_address(&state);
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if (!addr)
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return -EINVAL;
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#ifdef CONFIG_RETHOOK
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/*
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* Mark stacktraces with krethook functions on them
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* as unreliable.
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*/
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if (state.ip == (unsigned long)arch_rethook_trampoline)
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return -EINVAL;
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#endif
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if (!consume_entry(cookie, addr))
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return -EINVAL;
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}
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/* Check for stack corruption */
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if (unwind_error(&state))
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return -EINVAL;
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return 0;
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}
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void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
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const struct pt_regs *regs)
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{
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struct stack_frame_user __user *sf;
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unsigned long ip, sp;
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bool first = true;
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if (is_compat_task())
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return;
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if (!consume_entry(cookie, instruction_pointer(regs)))
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return;
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sf = (void __user *)user_stack_pointer(regs);
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pagefault_disable();
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while (1) {
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if (__get_user(sp, &sf->back_chain))
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break;
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if (__get_user(ip, &sf->gprs[8]))
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break;
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if (ip & 0x1) {
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/*
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* If the instruction address is invalid, and this
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* is the first stack frame, assume r14 has not
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* been written to the stack yet. Otherwise exit.
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*/
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if (first && !(regs->gprs[14] & 0x1))
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ip = regs->gprs[14];
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else
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break;
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}
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if (!consume_entry(cookie, ip))
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break;
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/* Sanity check: ABI requires SP to be aligned 8 bytes. */
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if (!sp || sp & 0x7)
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break;
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sf = (void __user *)sp;
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first = false;
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}
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pagefault_enable();
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}
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unsigned long return_address(unsigned int n)
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{
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struct unwind_state state;
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unsigned long addr;
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/* Increment to skip current stack entry */
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n++;
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unwind_for_each_frame(&state, NULL, NULL, 0) {
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addr = unwind_get_return_address(&state);
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if (!addr)
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break;
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if (!n--)
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return addr;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(return_address);
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