From fc024ebf24baedcef98310347abd2480662aca74 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Thu, 29 Jan 2026 13:39:03 +0100 Subject: [PATCH] symbols: ensure sorting by value yields reproducible outcome MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit qsort() implementations have freedom towards actions taken when two items compare equal. The latest with the introduction of fake "end" symbols, inconsistent sorting between the 1st and 2nd run can lead to extra "end" symbols in one of the runs, making the resulting symbol table partly unusable. (Note in particular that --warn-dup or --error-dup are passed only on the 2nd run, and only for xen.syms, and that option has the effect of doing a name sort ahead of doing the address sort. I.e. the inputs to the 2nd qsort() are pretty different between the 1st and 2nd runs.) Make the result stable by using original order to break ties. Fixes: d3b637fba31b ("symbols: arrange to know where functions end") Reported-by: Roger Pau Monné Signed-off-by: Jan Beulich Reviewed-by: Roger Pau Monné master commit: af3466ddd6490e2ff634bfdaca5a40725b466c2a master date: 2026-01-26 11:49:06 +0100 --- xen/tools/symbols.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/xen/tools/symbols.c b/xen/tools/symbols.c index 0af8a1e91c..a2b46d655c 100644 --- a/xen/tools/symbols.c +++ b/xen/tools/symbols.c @@ -40,6 +40,7 @@ struct sym_entry { unsigned long long addr; unsigned long size; unsigned int len; + unsigned int orig_idx; unsigned char *sym; char *orig_symbol; unsigned int addr_idx; @@ -247,6 +248,9 @@ static void read_map(FILE *in) exit (1); } } + + table[table_cnt].orig_idx = table_cnt; + if (read_symbol(in, &table[table_cnt]) == 0) table_cnt++; } @@ -639,7 +643,11 @@ static int compare_value(const void *p1, const void *p2) return -1; if (isupper(*sym2->sym)) return +1; - return 0; + + /* Explicitly request "keep original order" otherwise. */ + if (sym1->orig_idx < sym2->orig_idx) + return -1; + return sym1->orig_idx > sym2->orig_idx; } static int compare_name(const void *p1, const void *p2)