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Subject: [PATCH] tracing/x86: fix trace event registration for syscalls
 without arguments
From:   Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To:     Brian Gerst <brgerst@gmail.com>, linux-kernel@vger.kernel.org
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Dominik Brodowski <linux@dominikbrodowski.net>,
        Andy Lutomirski <luto@kernel.org>
Date:   Wed, 08 Apr 2020 21:13:10 +0300
Message-ID: <158636958997.7900.16485049455470033557.stgit@buzz>
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Sender: linux-kernel-owner@vger.kernel.org
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Syscalls without arguments now has no ABI subs, instead of that macro
SYSCALL_DEFINE0() defines __abi_sys_name as aliase to __do_sys_name.

As a result in find_syscall_meta() kallsyms_lookup() returns
"__do_sys_name" which does not match with declared trace event.

Also see commit 1c758a2202a6 ("tracing/x86: Update syscall trace events
to handle new prefixed syscall func names")

Fixes: d2b5de495ee9 ("x86/entry: Refactor SYSCALL_DEFINE0 macros")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 arch/x86/include/asm/ftrace.h |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 85be2f506272..70b96cae5b42 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -61,11 +61,12 @@ 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
-	 * "__x64_sys", "__ia32_sys" or simple "sys" prefix.
+	 * "__x64_sys", "__ia32_sys", "__do_sys" or simple "sys" prefix.
 	 */
 	return !strcmp(sym + 3, name + 3) ||
 		(!strncmp(sym, "__x64_", 6) && !strcmp(sym + 9, name + 3)) ||
-		(!strncmp(sym, "__ia32_", 7) && !strcmp(sym + 10, name + 3));
+		(!strncmp(sym, "__ia32_", 7) && !strcmp(sym + 10, name + 3)) ||
+		(!strncmp(sym, "__do_sys", 8) && !strcmp(sym + 8, name + 3));
 }
 
 #ifndef COMPILE_OFFSETS