From a20896709d817e3291666e4c80ed94f724b8382f Mon Sep 17 00:00:00 2001
From: Giuliano Belinassi <gbelinassi@suse.de>
Date: Thu, 23 Feb 2023 16:31:38 -0300
Subject: [PATCH] Fix `patches` not detecting libcrypto as livepatchable

libcrypto.so.1.1 required to read around 200 symbols in order for
`patch` to detect it as a livepatchable library.  Hence we bump
the number of symbols to read from 64 to 8000.  This value of 8000 is
found by analyzing all libraries found in /usr/lib64 and its subfolders
for how many symbols it would need to be read in order to decide if
the library is livepatchable.

Workarround #159

Signed-off-by: Giuliano Belinassi <gbelinassi@suse.de>
---
 scripts/collect.sh | 22 ++++++++++++++++++++++
 tools/patches.c    |  7 +++++--
 2 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100755 scripts/collect.sh

diff --git a/scripts/collect.sh b/scripts/collect.sh
new file mode 100755
index 00000000..e3fc43f7
--- /dev/null
+++ b/scripts/collect.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+
+# Look for the number of symbols and how many symbols will need to be read to
+# decide if a library is livepatchable or not in /usr/lib64 to collect
+# statistics.
+
+get_first_function_symbol()
+{
+  local realfile=$(readlink -f $1)
+  local symbol=$(readelf -D -sW $realfile | grep -E "FUNC[ ]*GLOBAL[ ]*DEFAULT[ ]*[0-9]+" | head -n 1 | awk '{ print substr($1, 1, length($1)-1) }')
+  local num_symbols=$(readelf -D -sW $realfile | tail -n 1 | awk '{ print substr($1, 1, length($1)-1) }')
+
+  echo "Analyzing $realfile"
+  echo "$realfile, $symbol", $num_symbols >> output.csv
+}
+
+rm -f output.csv
+for so in $(find "/usr/lib64/" -name "*.so"); do
+  get_first_function_symbol $so
+done
+
+sort -u output.csv -o output.csv
diff --git a/tools/patches.c b/tools/patches.c
index 524ece0a..564aa782 100644
--- a/tools/patches.c
+++ b/tools/patches.c
@@ -437,8 +437,11 @@ is_library_livepatchable(struct ulp_applied_patch *patch,
     ehdr_addr = 0x400000UL;
   }
 
-  /* Only look the first 64 symbols, else we may take too much time.  */
-  int len = MIN(obj->num_symbols, 64);
+  /* FIXME: Some applications take a very long time to decide if library is
+     livepatchable because the library has a lot of symbols.  In this case we
+     limit the number of symbols to read to a constant value.  Statistics shows
+     that 8000 is a reasonable number (see issue #159).  */
+  int len = MIN(obj->num_symbols, 8000);
 
   for (i = 0; i < len; i++) {
     ElfW(Sym) sym;