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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

From: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>

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

Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>
CC: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: Norbert Manthey <nmanthey@xxxxxxxxx>

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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