Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932569AbcJLIu4 (ORCPT ); Wed, 12 Oct 2016 04:50:56 -0400 Received: from ozlabs.org ([103.22.144.67]:42097 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932233AbcJLIuq (ORCPT ); Wed, 12 Oct 2016 04:50:46 -0400 From: Michael Ellerman To: Marcin Nowakowski , linux-kernel@vger.kernel.org Cc: linux-api@vger.kernel.org, luto@amacapital.net, rostedt@goodmis.org, Marcin Nowakowski , Ingo Molnar , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v3 03/11] tracing/syscalls: add compat syscall metadata In-Reply-To: <1476182576-15247-4-git-send-email-marcin.nowakowski@imgtec.com> References: <1476182576-15247-1-git-send-email-marcin.nowakowski@imgtec.com> <1476182576-15247-4-git-send-email-marcin.nowakowski@imgtec.com> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Date: Wed, 12 Oct 2016 19:50:39 +1100 Message-ID: <8737k254tc.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5831 Lines: 149 Marcin Nowakowski writes: > Now that compat syscalls are properly distinguished from native calls, > we can add metadata for compat syscalls as well. > All the macros used to generate the metadata are the same as for > standard syscalls, but with a compat_ prefix to distinguish them easily. > > Signed-off-by: Marcin Nowakowski > Cc: Steven Rostedt > Cc: Ingo Molnar > Cc: Benjamin Herrenschmidt > Cc: Paul Mackerras > Cc: Michael Ellerman > Cc: linuxppc-dev@lists.ozlabs.org > --- > arch/powerpc/include/asm/ftrace.h | 15 +++++--- > include/linux/compat.h | 74 +++++++++++++++++++++++++++++++++++++++ > kernel/trace/trace_syscalls.c | 8 +++-- > 3 files changed, 90 insertions(+), 7 deletions(-) > > diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h > index 686c5f7..9697a73 100644 > --- a/arch/powerpc/include/asm/ftrace.h > +++ b/arch/powerpc/include/asm/ftrace.h > @@ -73,12 +73,17 @@ struct dyn_arch_ftrace { > static inline bool arch_syscall_match_sym_name(const char *sym, const char *name) > { > /* > - * Compare the symbol name with the system call name. Skip the .sys or .SyS > - * prefix from the symbol name and the sys prefix from the system call name and > - * just match the rest. This is only needed on ppc64 since symbol names on > - * 32bit do not start with a period so the generic function will work. > + * Compare the symbol name with the system call name. Skip the .sys, > + * .SyS or .compat_sys prefix from the symbol name and the sys prefix > + * from the system call name and just match the rest. This is only > + * needed on ppc64 since symbol names on 32bit do not start with a > + * period so the generic function will work. > */ > - return !strcmp(sym + 4, name + 3); > + int prefix_len = 3; > + > + if (!strncasecmp(name, "compat_", 7)) > + prefix_len = 10; > + return !strcmp(sym + prefix_len + 1, name + prefix_len); > } It's annoying that we have to duplicate all that just to do a + 1. How about this as a precursor? cheers diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt index dd5f916b351d..bd65f2adeb09 100644 --- a/Documentation/trace/ftrace-design.txt +++ b/Documentation/trace/ftrace-design.txt @@ -226,10 +226,6 @@ You need very few things to get the syscalls tracing in an arch. - If the system call table on this arch is more complicated than a simple array of addresses of the system calls, implement an arch_syscall_addr to return the address of a given system call. -- If the symbol names of the system calls do not match the function names on - this arch, define ARCH_HAS_SYSCALL_MATCH_SYM_NAME in asm/ftrace.h and - implement arch_syscall_match_sym_name with the appropriate logic to return - true if the function name corresponds with the symbol name. - Tag this arch as HAVE_SYSCALL_TRACEPOINTS. diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 686c5f70eb84..dc48f5b2878d 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -60,6 +60,12 @@ struct dyn_arch_ftrace { struct module *mod; }; #endif /* CONFIG_DYNAMIC_FTRACE */ + +#ifdef PPC64_ELF_ABI_v1 +/* On ppc64 ABIv1 (BE) we have to skip the leading '.' in the symbol name */ +#define ARCH_SYM_NAME_SKIP_CHARS 1 +#endif + #endif /* __ASSEMBLY__ */ #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS @@ -67,20 +73,4 @@ struct dyn_arch_ftrace { #endif #endif -#if defined(CONFIG_FTRACE_SYSCALLS) && !defined(__ASSEMBLY__) -#ifdef PPC64_ELF_ABI_v1 -#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME -static inline bool arch_syscall_match_sym_name(const char *sym, const char *name) -{ - /* - * Compare the symbol name with the system call name. Skip the .sys or .SyS - * prefix from the symbol name and the sys prefix from the system call name and - * just match the rest. This is only needed on ppc64 since symbol names on - * 32bit do not start with a period so the generic function will work. - */ - return !strcmp(sym + 4, name + 3); -} -#endif -#endif /* CONFIG_FTRACE_SYSCALLS && !__ASSEMBLY__ */ - #endif /* _ASM_POWERPC_FTRACE */ diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index b2b6efc083a4..91a7315dbe43 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -31,8 +31,11 @@ extern struct syscall_metadata *__stop_syscalls_metadata[]; static struct syscall_metadata **syscalls_metadata; -#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME -static inline bool arch_syscall_match_sym_name(const char *sym, const char *name) +#ifndef ARCH_SYM_NAME_SKIP_CHARS +#define ARCH_SYM_NAME_SKIP_CHARS 0 +#endif + +static inline bool syscall_match_sym_name(const char *sym, const char *name) { /* * Only compare after the "sys" prefix. Archs that use @@ -40,9 +43,8 @@ static inline bool arch_syscall_match_sym_name(const char *sym, const char *name * with ".SyS" or ".sys" instead of "sys", leading to an unwanted * mismatch. */ - return !strcmp(sym + 3, name + 3); + return !strcmp(sym + 3 + ARCH_SYM_NAME_SKIP_CHARS, name + 3); } -#endif #ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS /* @@ -88,11 +90,11 @@ find_syscall_meta(unsigned long syscall) stop = __stop_syscalls_metadata; kallsyms_lookup(syscall, NULL, NULL, NULL, str); - if (arch_syscall_match_sym_name(str, "sys_ni_syscall")) + if (syscall_match_sym_name(str, "sys_ni_syscall")) return NULL; for ( ; start < stop; start++) { - if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name)) + if ((*start)->name && syscall_match_sym_name(str, (*start)->name)) return *start; } return NULL;