f7edb451fa
Most archs (well at least x86) store the function call return address on the stack before storing the local variables for the function. The max stack tracer depends on this in its algorithm to display the stack size of each function it finds in the back trace. Some archs (arm64), may store the return address (from its link register) just before calling a nested function. There's no reason to save the link register on leaf functions, as it wont be updated. This breaks the algorithm of the max stack tracer. Add a new define ARCH_FTRACE_SHIFT_STACK_TRACER that an architecture may set if it stores the return address (link register) after it stores the function's local variables, and have the stack trace shift the values of the mapped stack size to the appropriate functions. Link: 20190802094103.163576-1-jiping.ma2@windriver.com Reported-by: Jiping Ma <jiping.ma2@windriver.com> Acked-by: Will Deacon <will@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* arch/arm64/include/asm/ftrace.h
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*
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* Copyright (C) 2013 Linaro Limited
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* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
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*/
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#ifndef __ASM_FTRACE_H
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#define __ASM_FTRACE_H
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#include <asm/insn.h>
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#define HAVE_FUNCTION_GRAPH_FP_TEST
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#define MCOUNT_ADDR ((unsigned long)_mcount)
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#define MCOUNT_INSN_SIZE AARCH64_INSN_SIZE
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/*
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* Currently, gcc tends to save the link register after the local variables
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* on the stack. This causes the max stack tracer to report the function
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* frame sizes for the wrong functions. By defining
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* ARCH_FTRACE_SHIFT_STACK_TRACER, it will tell the stack tracer to expect
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* to find the return address on the stack after the local variables have
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* been set up.
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*
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* Note, this may change in the future, and we will need to deal with that
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* if it were to happen.
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*/
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#define ARCH_FTRACE_SHIFT_STACK_TRACER 1
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#ifndef __ASSEMBLY__
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#include <linux/compat.h>
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extern void _mcount(unsigned long);
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extern void *return_address(unsigned int);
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struct dyn_arch_ftrace {
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/* No extra data needed for arm64 */
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};
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extern unsigned long ftrace_graph_call;
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extern void return_to_handler(void);
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static inline unsigned long ftrace_call_adjust(unsigned long addr)
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{
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/*
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* addr is the address of the mcount call instruction.
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* recordmcount does the necessary offset calculation.
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*/
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return addr;
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}
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#define ftrace_return_address(n) return_address(n)
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/*
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* Because AArch32 mode does not share the same syscall table with AArch64,
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* tracing compat syscalls may result in reporting bogus syscalls or even
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* hang-up, so just do not trace them.
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* See kernel/trace/trace_syscalls.c
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*
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* x86 code says:
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* If the user really wants these, then they should use the
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* raw syscall tracepoints with filtering.
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*/
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#define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
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static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
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{
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return is_compat_task();
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}
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#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
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static inline bool arch_syscall_match_sym_name(const char *sym,
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const char *name)
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{
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/*
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* Since all syscall functions have __arm64_ prefix, we must skip it.
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* However, as we described above, we decided to ignore compat
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* syscalls, so we don't care about __arm64_compat_ prefix here.
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*/
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return !strcmp(sym + 8, name);
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}
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#endif /* ifndef __ASSEMBLY__ */
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#endif /* __ASM_FTRACE_H */
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