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[89.247.44.242]) by smtp.gmail.com with ESMTPSA id j23sm3339045wmo.26.2021.07.20.15.16.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Jul 2021 15:16:37 -0700 (PDT) From: treasure4paddy@gmail.com X-Google-Original-From: padmanabha.srinivasaiah@harman.com To: rostedt@goodmis.org, mingo@redhat.com Cc: samitolvanen@google.com, treasure4paddy@gmail.com, Padmanabha Srinivasaiah , Nathan Chancellor , Nick Desaulniers , linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH] tracing/syscalls: Clang cfi enable syscall events Date: Wed, 21 Jul 2021 00:15:41 +0200 Message-Id: <20210720221541.16164-1-padmanabha.srinivasaiah@harman.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Padmanabha Srinivasaiah With clang cfi syscall symbols are appended with .cfi_jt, hence syscall tracer can not find corresponding syscall name. And results in no syscall ftrace events with CFI. To fix this issue, this introduces custom cleanup_syscall_symbol_name() to strip postfix ".cfi_jt" before comparing syscall and symbol name. Signed-off-by: Padmanabha Srinivasaiah --- kernel/trace/trace_syscalls.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 8bfcd3b09422..dbc253fea34d 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -79,6 +79,27 @@ trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs) } #endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */ +#if defined(CONFIG_CFI_CLANG) && defined(CONFIG_LTO_CLANG_THIN) +/* + * For a syscall symbol, clang generated non-canonical local jump tables + * will have entry as .cfi_jt and address of this entry + * will be used to replace references to the syscall symbol. + * so we will strip the postfix from appended symbol name. + */ +static inline bool cleanup_syscall_symbol_name(char *s) +{ + char *res; + + res = strrchr(s, '.'); + if (res) + *res = '\0'; + + return res != NULL; +} +#else +static inline bool cleanup_syscall_symbol_name(char *s) { return false; } +#endif + static __init struct syscall_metadata * find_syscall_meta(unsigned long syscall) { @@ -90,6 +111,7 @@ find_syscall_meta(unsigned long syscall) start = __start_syscalls_metadata; stop = __stop_syscalls_metadata; kallsyms_lookup(syscall, NULL, NULL, NULL, str); + cleanup_syscall_symbol_name(str); if (arch_syscall_match_sym_name(str, "sys_ni_syscall")) return NULL; -- 2.17.1