linux-kernel - [PATCH 4.14 120/189] powerpc/trace/syscalls: Update syscall name matching logic

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Date:   Mon, 18 Jun 2018 10:13:36 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Michael Ellerman <mpe@...erman.id.au>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.14 120/189] powerpc/trace/syscalls: Update syscall name matching logic

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>

[ Upstream commit 0b7758aaf6543b9a10c8671db559e9d374a3fd95 ]

On powerpc64 ABIv1, we are enabling syscall tracing for only ~20
syscalls. This is due to commit e145242ea0df6 ("syscalls/core,
syscalls/x86: Clean up syscall stub naming convention") which has
changed the syscall entry wrapper prefix from "SyS" to "__se_sys".

Update the logic for ABIv1 to not just skip the initial dot, but also
the "__se_sys" prefix.

Fixes: commit e145242ea0df6 ("syscalls/core, syscalls/x86: Clean up syscall stub naming convention")
Reported-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/powerpc/include/asm/ftrace.h |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -73,13 +73,9 @@ struct dyn_arch_ftrace {
 #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);
+	/* We need to skip past the initial dot, and the __se_sys alias */
+	return !strcmp(sym + 1, name) ||
+		(!strncmp(sym, ".__se_sys", 9) && !strcmp(sym + 6, name));
 }
 #endif
 #endif /* CONFIG_FTRACE_SYSCALLS && !__ASSEMBLY__ */