linux-kernel - [PATCH 3/3] x86/unwind/orc: Simplify unwind

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Message-Id: <20200807041802.18639-4-changhuaixin@linux.alibaba.com>
Date:   Fri,  7 Aug 2020 12:18:02 +0800
From:   Huaixin Chang <changhuaixin@...ux.alibaba.com>
To:     changhuaixin@...ux.alibaba.com
Cc:     bp@...en8.de, hpa@...or.com, jpoimboe@...hat.com,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        luto@...capital.net, michal.lkml@...kovi.net, mingo@...hat.com,
        peterz@...radead.org, tglx@...utronix.de, x86@...nel.org,
        yamada.masahiro@...ionext.com
Subject: [PATCH 3/3] x86/unwind/orc: Simplify unwind_init() for x86 boot

The ORC fast lookup table is built by scripts/sorttable tool. All that
is left is setting lookup_num_blocks.

Signed-off-by: Huaixin Chang <changhuaixin@...ux.alibaba.com>
Signed-off-by: Shile Zhang <shile.zhang@...ux.alibaba.com>
---
 arch/x86/kernel/unwind_orc.c | 41 ++---------------------------------------
 1 file changed, 2 insertions(+), 39 deletions(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index ec88bbe08a32..29890389b4f6 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -264,48 +264,11 @@ void unwind_module_init(struct module *mod, void *_orc_ip, size_t orc_ip_size,
 
 void __init unwind_init(void)
 {
-	size_t orc_ip_size = (void *)__stop_orc_unwind_ip - (void *)__start_orc_unwind_ip;
-	size_t orc_size = (void *)__stop_orc_unwind - (void *)__start_orc_unwind;
-	size_t num_entries = orc_ip_size / sizeof(int);
-	struct orc_entry *orc;
-	int i;
-
-	if (!num_entries || orc_ip_size % sizeof(int) != 0 ||
-	    orc_size % sizeof(struct orc_entry) != 0 ||
-	    num_entries != orc_size / sizeof(struct orc_entry)) {
-		orc_warn("WARNING: Bad or missing .orc_unwind table.  Disabling unwinder.\n");
-		return;
-	}
-
 	/*
-	 * Note, the orc_unwind and orc_unwind_ip tables were already
-	 * sorted at build time via the 'sorttable' tool.
-	 * It's ready for binary search straight away, no need to sort it.
+	 * All ORC tables are sorted and built via sorttable tool. Initialize
+	 * lookup_num_blocks only.
 	 */
-
-	/* Initialize the fast lookup table: */
 	lookup_num_blocks = orc_lookup_end - orc_lookup;
-	for (i = 0; i < lookup_num_blocks-1; i++) {
-		orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind,
-				 num_entries,
-				 LOOKUP_START_IP + (LOOKUP_BLOCK_SIZE * i));
-		if (!orc) {
-			orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
-			return;
-		}
-
-		orc_lookup[i] = orc - __start_orc_unwind;
-	}
-
-	/* Initialize the ending block: */
-	orc = __orc_find(__start_orc_unwind_ip, __start_orc_unwind, num_entries,
-			 LOOKUP_STOP_IP);
-	if (!orc) {
-		orc_warn("WARNING: Corrupt .orc_unwind table.  Disabling unwinder.\n");
-		return;
-	}
-	orc_lookup[lookup_num_blocks-1] = orc - __start_orc_unwind;
-
 	orc_init = true;
 }
 
-- 
2.14.4.44.g2045bb6