linux-kernel - [PATCH] scripts/sorttable: Fix ORC unwind table sorting on big endian

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Message-ID: <patch.git-45d71f2e4f14.your-ad-here.call-01605357883-ext-1218@work.hours>
Date:   Sat, 14 Nov 2020 13:53:10 +0100
From:   Vasily Gorbik <gor@...ux.ibm.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Shile Zhang <shile.zhang@...ux.alibaba.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Miroslav Benes <mbenes@...e.cz>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Julien Thierry <jthierry@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] scripts/sorttable: Fix ORC unwind table sorting on big endian

Currently when x86_64 kernel is cross compiled on big endian hardware
ORC unwind table is not sorted correctly. Due to missing byte swaps and
treating size as 4-byte value ORC sections sizes end up as 0 and the
problem is silently ignored.

Make ORC unwind table sorting endianness aware.

Signed-off-by: Vasily Gorbik <gor@...ux.ibm.com>
---
 This goes on top of the patch series:
 http://lkml.kernel.org/r/cover.thread-1e2854.your-ad-here.call-01605220128-ext-6070@work.hours

 scripts/sorttable.h | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/scripts/sorttable.h b/scripts/sorttable.h
index a2baa2fefb13..99f3fa1767d1 100644
--- a/scripts/sorttable.h
+++ b/scripts/sorttable.h
@@ -59,6 +59,8 @@
 # define uint_t			uint64_t
 # define _r			r8
 # define _w			w8
+# define _r4			r
+# define _w4			w
 #else
 # define extable_ent_size	8
 # define compare_extable	compare_extable_32
@@ -80,6 +82,8 @@
 # define uint_t			uint32_t
 # define _r			r
 # define _w			w
+# define _r4			r
+# define _w4			w
 #endif
 
 #if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
@@ -98,7 +102,7 @@ pthread_t orc_sort_thread;
 
 static inline unsigned long orc_ip(const int *ip)
 {
-	return (unsigned long)ip + *ip;
+	return (unsigned long)ip + (int)_r4((uint32_t *)ip);
 }
 
 static int orc_sort_cmp(const void *_a, const void *_b)
@@ -158,7 +162,7 @@ static void *sort_orctable(void *arg)
 	/* initialize indices array, convert ip_table to absolute address */
 	for (i = 0; i < num_entries; i++) {
 		idxs[i] = i;
-		tmp_orc_ip_table[i] = g_orc_ip_table[i] + i * sizeof(int);
+		tmp_orc_ip_table[i] = (int)_r4((uint32_t *)&g_orc_ip_table[i]) + i * sizeof(int);
 	}
 	memcpy(tmp_orc_table, g_orc_table, orc_size);
 
@@ -169,7 +173,7 @@ static void *sort_orctable(void *arg)
 			continue;
 
 		/* convert back to relative address */
-		g_orc_ip_table[i] = tmp_orc_ip_table[idxs[i]] - i * sizeof(int);
+		_w4(tmp_orc_ip_table[idxs[i]] - i * sizeof(int), (uint32_t *)&g_orc_ip_table[i]);
 		g_orc_table[i] = tmp_orc_table[idxs[i]];
 	}
 
@@ -256,14 +260,12 @@ static int do_sort(Elf_Ehdr *ehdr,
 #if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
 		/* locate the ORC unwind tables */
 		if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
-			orc_ip_size = s->sh_size;
-			g_orc_ip_table = (int *)((void *)ehdr +
-						   s->sh_offset);
+			orc_ip_size = _r(&s->sh_size);
+			g_orc_ip_table = (int *)((void *)ehdr + _r(&s->sh_offset));
 		}
 		if (!strcmp(secstrings + idx, ".orc_unwind")) {
-			orc_size = s->sh_size;
-			g_orc_table = (struct orc_entry *)((void *)ehdr +
-							     s->sh_offset);
+			orc_size = _r(&s->sh_size);
+			g_orc_table = (struct orc_entry *)((void *)ehdr + _r(&s->sh_offset));
 		}
 #endif
 	} /* for loop */
-- 
2.25.4