linux-kernel - [PATCH v1 1/4] powerpc/ftrace: Also save r1 in ftrace

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Message-Id: <ff535e86d3a69376a6d89168511d4e403835f18b.1644949750.git.christophe.leroy@csgroup.eu>
Date:   Tue, 15 Feb 2022 19:31:22 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        "Naveen N . Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Subject: [PATCH v1 1/4] powerpc/ftrace: Also save r1 in ftrace_caller()

Also save r1 in ftrace_caller()

r1 is needed during unwinding when the function_graph tracer
is active.

Reported-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
Fixes: 830213786c49 ("powerpc/ftrace: directly call of function graph tracer by ftrace caller")
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/trace/ftrace_mprofile.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kernel/trace/ftrace_mprofile.S b/arch/powerpc/kernel/trace/ftrace_mprofile.S
index 56da60e98327..8443902d5a05 100644
--- a/arch/powerpc/kernel/trace/ftrace_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_mprofile.S
@@ -173,6 +173,10 @@ _GLOBAL(ftrace_caller)
 	beq	ftrace_no_trace
 #endif
 
+	/* Save previous stack pointer (r1) */
+	addi	r8, r1, SWITCH_FRAME_SIZE
+	PPC_STL	r8, GPR1(r1)
+
 	/* Get the _mcount() call site out of LR */
 	mflr	r7
 	PPC_STL     r7, _NIP(r1)
-- 
2.34.1