[PATCH] x86/livepatch: Fail the build if duplicate symbols exist

From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xen.org>
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
	"Wei Liu" <wei.liu2@citrix.com>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ross Lagerwall" <ross.lagerwall@citrix.com>,
	"Julien Grall" <julien.grall@arm.com>,
	"Norbert Manthey" <nmanthey@amazon.de>,
	"Jan Beulich" <JBeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [PATCH] x86/livepatch: Fail the build if duplicate symbols exist
Date: Fri, 5 Apr 2019 20:26:04 +0100	[thread overview]
Message-ID: <1554492364-21684-1-git-send-email-andrew.cooper3@citrix.com> (raw)

From: Ross Lagerwall <ross.lagerwall@citrix.com>

The binary diffing algorithm used by xen-livepatch depends on having unique
symbols.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Roger Pau Monné <roger.pau@citrix.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien.grall@arm.com>
CC: Ross Lagerwall <ross.lagerwall@citrix.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Norbert Manthey <nmanthey@amazon.de>

This patch has been part of the XenServer patchqueue for ages, and should have
been upstreamed sooner.  It obviously can't be applied while the "block
speculation" issue is outstanding.
---
 xen/arch/x86/Makefile |  1 +
 xen/tools/symbols.c   | 11 +++++++++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index ef09939..d4ae46b 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -98,6 +98,7 @@ endif
 
 syms-warn-dup-y := --warn-dup
 syms-warn-dup-$(CONFIG_SUPPRESS_DUPLICATE_SYMBOL_WARNINGS) :=
+syms-warn-dup-$(CONFIG_LIVEPATCH) := --error-dup
 
 $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32
 	./boot/mkelf32 $(notes_phdrs) $(TARGET)-syms $(TARGET) $(XEN_IMG_OFFSET) \
diff --git a/xen/tools/symbols.c b/xen/tools/symbols.c
index 05139d1..9f9e2c9 100644
--- a/xen/tools/symbols.c
+++ b/xen/tools/symbols.c
@@ -599,7 +599,7 @@ static int compare_name(const void *p1, const void *p2)
 int main(int argc, char **argv)
 {
 	unsigned int i;
-	bool unsorted = false, warn_dup = false;
+	bool unsorted = false, warn_dup = false, error_dup = false, found_dup = false;
 
 	if (argc >= 2) {
 		for (i = 1; i < argc; i++) {
@@ -619,6 +619,8 @@ int main(int argc, char **argv)
 				sort_by_name = 1;
 			else if (strcmp(argv[i], "--warn-dup") == 0)
 				warn_dup = true;
+			else if (strcmp(argv[i], "--error-dup") == 0)
+				warn_dup = error_dup = true;
 			else if (strcmp(argv[i], "--xensyms") == 0)
 				map_only = true;
 			else
@@ -634,14 +636,19 @@ int main(int argc, char **argv)
 		for (i = 1; i < table_cnt; ++i)
 			if (strcmp(SYMBOL_NAME(table + i - 1),
 				   SYMBOL_NAME(table + i)) == 0 &&
-			    table[i - 1].addr != table[i].addr)
+			    table[i - 1].addr != table[i].addr) {
 				fprintf(stderr,
 					"Duplicate symbol '%s' (%llx != %llx)\n",
 					SYMBOL_NAME(table + i),
 					table[i].addr, table[i - 1].addr);
+				found_dup = true;
+			}
 		unsorted = true;
 	}
 
+	if (error_dup && found_dup)
+		exit(1);
+
 	if (unsorted)
 		qsort(table, table_cnt, sizeof(*table), compare_value);
 
-- 
2.1.4


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