linux-kernel - [PATCH 3.16 099/202] MIPS: Remove function size check in get_frame

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Message-ID: <lsq.1556377989.99898756@decadent.org.uk>
Date:   Sat, 27 Apr 2019 16:13:09 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "" <yamada.masahiro@...ionext.com>,
        "" <linux-mips@...r.kernel.org>, "" <peterz@...radead.org>,
        "" <mingo@...nel.org>, "" <jhogan@...nel.org>,
        "Paul Burton" <paul.burton@...s.com>,
        "Tony Wu" <tonywu@...ltek.com>, "" <ralf@...ux-mips.org>,
        "" <macro@...s.com>, "Jun-Ru Chang" <jrjang@...ltek.com>
Subject: [PATCH 3.16 099/202] MIPS: Remove function size check in
 get_frame_info()

3.16.66-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Jun-Ru Chang <jrjang@...ltek.com>

commit 2b424cfc69728224fcb5fad138ea7260728e0901 upstream.

Patch (b6c7a324df37b "MIPS: Fix get_frame_info() handling of
microMIPS function size.") introduces additional function size
check for microMIPS by only checking insn between ip and ip + func_size.
However, func_size in get_frame_info() is always 0 if KALLSYMS is not
enabled. This causes get_frame_info() to return immediately without
calculating correct frame_size, which in turn causes "Can't analyze
schedule() prologue" warning messages at boot time.

This patch removes func_size check, and let the frame_size check run
up to 128 insns for both MIPS and microMIPS.

Signed-off-by: Jun-Ru Chang <jrjang@...ltek.com>
Signed-off-by: Tony Wu <tonywu@...ltek.com>
Signed-off-by: Paul Burton <paul.burton@...s.com>
Fixes: b6c7a324df37b ("MIPS: Fix get_frame_info() handling of microMIPS function size.")
Cc: <ralf@...ux-mips.org>
Cc: <jhogan@...nel.org>
Cc: <macro@...s.com>
Cc: <yamada.masahiro@...ionext.com>
Cc: <peterz@...radead.org>
Cc: <mingo@...nel.org>
Cc: <linux-mips@...r.kernel.org>
Cc: <linux-kernel@...r.kernel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/mips/kernel/process.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -373,7 +373,7 @@ static inline int is_sp_move_ins(union m
 static int get_frame_info(struct mips_frame_info *info)
 {
 	bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
-	union mips_instruction insn, *ip, *ip_end;
+	union mips_instruction insn, *ip;
 	const unsigned int max_insns = 128;
 	unsigned int last_insn_size = 0;
 	unsigned int i;
@@ -385,10 +385,9 @@ static int get_frame_info(struct mips_fr
 	if (!ip)
 		goto err;
 
-	ip_end = (void *)ip + info->func_size;
-
-	for (i = 0; i < max_insns && ip < ip_end; i++) {
+	for (i = 0; i < max_insns; i++) {
 		ip = (void *)ip + last_insn_size;
+
 		if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
 			insn.word = ip->halfword[0] << 16;
 			last_insn_size = 2;