linux-kernel - [for-next][PATCH 4/4] scripts/sorttable: Allow matches to functions before function entry

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250226010616.944876524@goodmis.org>
Date: Tue, 25 Feb 2025 20:06:00 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Masahiro Yamada <masahiroy@...nel.org>,
 Catalin Marinas <catalin.marinas@....com>,
 Will Deacon <will@...nel.org>,
 "Arnd Bergmann" <arnd@...db.de>,
 Mark Brown <broonie@...nel.org>,
 Nathan Chancellor <nathan@...nel.org>
Subject: [for-next][PATCH 4/4] scripts/sorttable: Allow matches to functions before function entry

From: Steven Rostedt <rostedt@...dmis.org>

ARM 64 uses -fpatchable-function-entry=4,2 which adds padding before the
function and the addresses in the mcount_loc point there instead of the
function entry that is returned by nm. In order to find a function from nm
to make sure it's not an unused weak function, the entries in the
mcount_loc section needs to match the entries from nm. Since it can be an
instruction before the entry, add a before_func variable that ARM 64 can
set to 8, and if the mcount_loc entry is within 8 bytes of the nm function
entry, then it will be considered a match.

Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Masahiro Yamada <masahiroy@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: "Arnd Bergmann" <arnd@...db.de>
Cc: Mark Brown <broonie@...nel.org>
Link: https://lore.kernel.org/20250225182054.815536219@goodmis.org
Fixes: ef378c3b82338 ("scripts/sorttable: Zero out weak functions in mcount_loc table")
Tested-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 scripts/sorttable.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 07ad8116bc8d..7b4b3714b1af 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -611,13 +611,16 @@ static int add_field(uint64_t addr, uint64_t size)
 	return 0;
 }
 
+/* Used for when mcount/fentry is before the function entry */
+static int before_func;
+
 /* Only return match if the address lies inside the function size */
 static int cmp_func_addr(const void *K, const void *A)
 {
 	uint64_t key = *(const uint64_t *)K;
 	const struct func_info *a = A;
 
-	if (key < a->addr)
+	if (key + before_func < a->addr)
 		return -1;
 	return key >= a->addr + a->size;
 }
@@ -1253,6 +1256,8 @@ static int do_file(char const *const fname, void *addr)
 #ifdef MCOUNT_SORT_ENABLED
 		sort_reloc = true;
 		rela_type = 0x403;
+		/* arm64 uses patchable function entry placing before function */
+		before_func = 8;
 #endif
 		/* fallthrough */
 	case EM_386:
-- 
2.47.2