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02a474ca26
Currently, the only way to get access to the registers of a function via a ftrace callback is to set the "FL_SAVE_REGS" bit in the ftrace_ops. But as this saves all regs as if a breakpoint were to trigger (for use with kprobes), it is expensive. The regs are already saved on the stack for the default ftrace callbacks, as that is required otherwise a function being traced will get the wrong arguments and possibly crash. And on x86, the arguments are already stored where they would be on a pt_regs structure to use that code for both the regs version of a callback, it makes sense to pass that information always to all functions. If an architecture does this (as x86_64 now does), it is to set HAVE_DYNAMIC_FTRACE_WITH_ARGS, and this will let the generic code that it could have access to arguments without having to set the flags. This also includes having the stack pointer being saved, which could be used for accessing arguments on the stack, as well as having the function graph tracer not require its own trampoline! Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
116 lines
3.1 KiB
C
116 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_FTRACE_H
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#define _ASM_X86_FTRACE_H
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#ifdef CONFIG_FUNCTION_TRACER
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#ifndef CC_USING_FENTRY
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# error Compiler does not support fentry?
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#endif
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# define MCOUNT_ADDR ((unsigned long)(__fentry__))
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#define MCOUNT_INSN_SIZE 5 /* sizeof mcount call */
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#ifdef CONFIG_DYNAMIC_FTRACE
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#define ARCH_SUPPORTS_FTRACE_OPS 1
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#endif
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#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
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#ifndef __ASSEMBLY__
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extern atomic_t modifying_ftrace_code;
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extern void __fentry__(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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/*
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* When a ftrace registered caller is tracing a function that is
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* also set by a register_ftrace_direct() call, it needs to be
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* differentiated in the ftrace_caller trampoline. To do this, we
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* place the direct caller in the ORIG_AX part of pt_regs. This
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* tells the ftrace_caller that there's a direct caller.
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*/
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static inline void arch_ftrace_set_direct_caller(struct pt_regs *regs, unsigned long addr)
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{
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/* Emulate a call */
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regs->orig_ax = addr;
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}
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#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
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struct ftrace_regs {
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struct pt_regs regs;
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};
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static __always_inline struct pt_regs *
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arch_ftrace_get_regs(struct ftrace_regs *fregs)
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{
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/* Only when FL_SAVE_REGS is set, cs will be non zero */
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if (!fregs->regs.cs)
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return NULL;
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return &fregs->regs;
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}
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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struct dyn_arch_ftrace {
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/* No extra data needed for x86 */
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};
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#define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifndef __ASSEMBLY__
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#if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_DYNAMIC_FTRACE)
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extern void set_ftrace_ops_ro(void);
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#else
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static inline void set_ftrace_ops_ro(void) { }
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#endif
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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, const char *name)
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{
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/*
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* Compare the symbol name with the system call name. Skip the
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* "__x64_sys", "__ia32_sys", "__do_sys" or simple "sys" prefix.
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*/
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return !strcmp(sym + 3, name + 3) ||
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(!strncmp(sym, "__x64_", 6) && !strcmp(sym + 9, name + 3)) ||
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(!strncmp(sym, "__ia32_", 7) && !strcmp(sym + 10, name + 3)) ||
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(!strncmp(sym, "__do_sys", 8) && !strcmp(sym + 8, name + 3));
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}
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#ifndef COMPILE_OFFSETS
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#if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_IA32_EMULATION)
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#include <linux/compat.h>
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/*
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* Because ia32 syscalls do not map to x86_64 syscall numbers
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* this screws up the trace output when tracing a ia32 task.
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* Instead of reporting bogus syscalls, just do not trace them.
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*
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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 1
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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 in_32bit_syscall();
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}
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#endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_IA32_EMULATION */
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#endif /* !COMPILE_OFFSETS */
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_FTRACE_H */
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