Message-ID: <CAE-0n53cOFJFOOV-YOc0MzbiLr9FvaJw=ucs2SNNGOeznYzVLw@mail.gmail.com>
Date:   Thu, 17 Feb 2022 17:27:33 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Mark Rutland <mark.rutland@....com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: arm64 ftrace fixes for v5.4.y

Hi stable maintainers,

I recently ran into an issue where trying to load a module with jump
table entries crashes the system when function tracing is enabled. The
crash happens because ftrace is modifying the code and then marking it
as read-only too early. ftrace_make_call() calls module_enable_ro(mod,
true) before module init is over because ftrace_module_enable() calls
__ftrace_replace_code() which does FTRACE_UPDATE_MAKE_CALL. All this
code is gone now upstream but is still present on v5.4 stable kernels. I
picked this set of patches to v5.4 and it fixed it for me.

fbf6c73c5b26 ftrace: add ftrace_init_nop()
a1326b17ac03 module/ftrace: handle patchable-function-entry
bd8b21d3dd66 arm64: module: rework special section handling
f1a54ae9af0d arm64: module/ftrace: intialize PLT at load time

after doing that I ran into another issue because I'm using clang. Would
it be possible to pick two more patches to the stable tree to silence
this module warning from sysfs complaining about
/module/<modname>/sections/__patchable_function_entries being
duplicated?

dd2776222abb kbuild: lto: merge module sections
6a3193cdd5e5 kbuild: lto: Merge module sections if and only if
CONFIG_LTO_CLANG is enabled

All of these apply cleanly to v5.4.y stable branch.

Crash below.

 Unable to handle kernel write to read-only memory at virtual address
ffffffd1b81fc0b0
 Mem abort info:
   ESR = 0x9600004f
   EC = 0x25: DABT (current EL), IL = 32 bits
   SET = 0, FnV = 0
   EA = 0, S1PTW = 0
 Data abort info:
   ISV = 0, ISS = 0x0000004f
   CM = 0, WnR = 1
 swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000081bc1000
 [ffffffd1b81fc0b0] pgd=0000000271858003, pud=0000000271858003,
pmd=0000000266c05003, pte=00600001f3f4df93
 Internal error: Oops: 9600004f [#1] PREEMPT SMP
 Modules linked in: vsock(+) <a bunch more modules>
 CPU: 5 PID: 6254 Comm: modprobe Not tainted 5.4.177 #19
 Hardware name: Google Lazor (rev3 - 8) with KB Backlight (DT)
 pstate: 60400009 (nZCv daif +PAN -UAO)
 pc : jump_label_swap+0x2c/0x68
 lr : jump_label_swap+0x18/0x68
 sp : ffffffc01946bb10
 x29: ffffffc01946bb10 x28: 00000000000000b0
 x27: 0000000000000010 x26: 00000000000000b0
 x25: 00000000000001a0 x24: ffffffd1b81fc180
 x23: ffffffd2036540fc x22: ffffffd1b81fc000
 x21: 0000000000000010 x20: ffffffd1b81fc0b0
 x19: ffffffd1b81fc180 x18: 0000000000000000
 x17: ffffffd204006e08 x16: 0000000000006000
 x15: ffffffd1b8209000 x14: 0066ba79a6ffffff
 x13: 0000000000000004 x12: 000000004c55e4d8
 x11: 00000000ffffd9f0 x10: 00000000ffffd754
 x9 : ffffffffffffff30 x8 : 00000000ffffe2ec
 x7 : fefefefefefefefe x6 : 00000000000341d5
 x5 : ffffffd203654164 x4 : ffffffd2036540fc
 x3 : 0000000000000000 x2 : ffffffc01946bb30
 x1 : ffffffd203654110 x0 : 00000000fffffff0
 Call trace:
  jump_label_swap+0x2c/0x68
  do_swap+0x98/0xa0
  sort_r+0x178/0x1a0
  sort+0x14/0x1c
  jump_label_module_notify+0x7c/0x2c0
  notifier_call_chain+0x58/0x90
  __blocking_notifier_call_chain+0x58/0x84
  blocking_notifier_call_chain+0x38/0x48
  prepare_coming_module+0x30/0x3c
  load_module+0xda4/0xf8c
  __arm64_sys_finit_module+0xa4/0xdc
  el0_svc_common+0xb4/0x17c
  el0_svc_compat_handler+0x2c/0x58
  el0_svc_compat+0x8/0x2c
 Code: cb130289 29402e8a f940068c 4b090108 (b9000288)

Powered by blists - more mailing lists