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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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562e14f722
There's two methods of enabling function tracing in Linux on x86. One is with just "gcc -pg" and the other is "gcc -pg -mfentry". The former will use calls to a special function "mcount" after the frame is set up in all C functions. The latter will add calls to a special function called "fentry" as the very first instruction of all C functions. At compile time, there is a check to see if gcc supports, -mfentry, and if it does, it will use that, because it is more versatile and less error prone for function tracing. Starting with v4.19, the minimum gcc supported to build the Linux kernel, was raised to version 4.6. That also happens to be the first gcc version to support -mfentry. Since on x86, using gcc versions from 4.6 and beyond will unconditionally enable the -mfentry, it will no longer use mcount as the method for inserting calls into the C functions of the kernel. This means that there is no point in continuing to maintain mcount in x86. Remove support for using mcount. This makes the code less complex, and will also allow it to be simplified in the future. Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
84 lines
2.1 KiB
C
84 lines
2.1 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 void mcount(void);
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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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#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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int ftrace_int3_handler(struct pt_regs *regs);
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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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#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" 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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}
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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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