linux-kernel - [PATCH v2 2/5] powerpc: kretprobes: override default function entry offset

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Message-Id: <e27a624a724f1b00d09e769cbce24abdb27d8688.1487770934.git.naveen.n.rao@linux.vnet.ibm.com>
Date:   Wed, 22 Feb 2017 19:23:38 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...hat.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 2/5] powerpc: kretprobes: override default function entry offset

With ABIv2, we offset 8 bytes into a function to get at the local entry
point.

Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
 arch/powerpc/kernel/kprobes.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 735ff3d3f77d..e37b76b8b6b2 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -131,6 +131,15 @@ static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
 	kcb->kprobe_saved_msr = regs->msr;
 }
 
+bool arch_function_offset_within_entry(unsigned long offset)
+{
+#ifdef PPC64_ELF_ABI_v2
+	return offset <= 8;
+#else
+	return !offset;
+#endif
+}
+
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				      struct pt_regs *regs)
 {
-- 
2.11.0