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Message-ID: <4A8A2B45-FD48-4085-9526-2C0031342299@fb.com>
Date: Mon, 18 Jul 2022 05:46:30 +0000
From: Song Liu <songliubraving@...com>
To: kernel test robot <lkp@...el.com>
CC: Song Liu <song@...nel.org>, bpf <bpf@...r.kernel.org>,
lkml <linux-kernel@...r.kernel.org>,
"live-patching@...r.kernel.org" <live-patching@...r.kernel.org>,
"llvm@...ts.linux.dev" <llvm@...ts.linux.dev>,
"kbuild-all@...ts.01.org" <kbuild-all@...ts.01.org>,
"daniel@...earbox.net" <daniel@...earbox.net>,
Kernel Team <Kernel-team@...com>,
"jolsa@...nel.org" <jolsa@...nel.org>,
"rostedt@...dmis.org" <rostedt@...dmis.org>
Subject: Re: [PATCH v3 bpf-next 2/4] ftrace: allow IPMODIFY and DIRECT ops on
the same function
> On Jul 17, 2022, at 8:36 PM, kernel test robot <lkp@...el.com> wrote:
>
> Hi Song,
>
> I love your patch! Yet something to improve:
>
> [auto build test ERROR on bpf-next/master]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Song-Liu/ftrace-host-klp-and-bpf-trampoline-together/20220718-081533
> base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
> config: x86_64-randconfig-a001 (https://download.01.org/0day-ci/archive/20220718/202207181140.tqIgD0Jp-lkp@intel.com/config )
> compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d74b88c69dc2644bd0dc5d64e2d7413a0d4040e5)
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # https://github.com/intel-lab-lkp/linux/commit/1535f287d288f9b7540ec50f56da1fe437ac6512
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Song-Liu/ftrace-host-klp-and-bpf-trampoline-together/20220718-081533
> git checkout 1535f287d288f9b7540ec50f56da1fe437ac6512
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@...el.com>
>
> All errors (new ones prefixed by >>):
>
>>> kernel/trace/ftrace.c:8082:14: error: use of undeclared identifier 'direct_mutex'; did you mean 'event_mutex'?
> mutex_lock(&direct_mutex);
> ^~~~~~~~~~~~
> event_mutex
Folded the the fix in. I guess this should also fail on v2, but
the kernel test robot didn't seem to find it.
Song
> include/linux/mutex.h:187:44: note: expanded from macro 'mutex_lock'
> #define mutex_lock(lock) mutex_lock_nested(lock, 0)
> ^
> kernel/trace/trace.h:1523:21: note: 'event_mutex' declared here
> extern struct mutex event_mutex;
> ^
>>> kernel/trace/ftrace.c:8084:14: error: no member named 'func_hash' in 'struct ftrace_ops'
> hash = ops->func_hash->filter_hash;
> ~~~ ^
>>> kernel/trace/ftrace.c:8095:9: error: call to undeclared function 'ops_references_ip'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
> if (ops_references_ip(op, ip)) {
> ^
>>> kernel/trace/ftrace.c:8103:14: error: no member named 'ops_func' in 'struct ftrace_ops'
> if (!op->ops_func) {
> ~~ ^
> kernel/trace/ftrace.c:8107:15: error: no member named 'ops_func' in 'struct ftrace_ops'
> ret = op->ops_func(op, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER);
> ~~ ^
> kernel/trace/ftrace.c:8122:16: error: use of undeclared identifier 'direct_mutex'; did you mean 'event_mutex'?
> mutex_unlock(&direct_mutex);
> ^~~~~~~~~~~~
> event_mutex
> kernel/trace/trace.h:1523:21: note: 'event_mutex' declared here
> extern struct mutex event_mutex;
> ^
> kernel/trace/ftrace.c:8158:17: error: use of undeclared identifier 'direct_mutex'; did you mean 'event_mutex'?
> mutex_unlock(&direct_mutex);
> ^~~~~~~~~~~~
> event_mutex
> kernel/trace/trace.h:1523:21: note: 'event_mutex' declared here
> extern struct mutex event_mutex;
> ^
> kernel/trace/ftrace.c:8178:14: error: use of undeclared identifier 'direct_mutex'; did you mean 'event_mutex'?
> mutex_lock(&direct_mutex);
> ^~~~~~~~~~~~
> event_mutex
> include/linux/mutex.h:187:44: note: expanded from macro 'mutex_lock'
> #define mutex_lock(lock) mutex_lock_nested(lock, 0)
> ^
> kernel/trace/trace.h:1523:21: note: 'event_mutex' declared here
> extern struct mutex event_mutex;
> ^
> kernel/trace/ftrace.c:8180:14: error: no member named 'func_hash' in 'struct ftrace_ops'
> hash = ops->func_hash->filter_hash;
> ~~~ ^
> kernel/trace/ftrace.c:8191:9: error: call to undeclared function 'ops_references_ip'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
> if (ops_references_ip(op, ip)) {
> ^
> kernel/trace/ftrace.c:8199:24: error: no member named 'ops_func' in 'struct ftrace_ops'
> if (found_op && op->ops_func)
> ~~ ^
> kernel/trace/ftrace.c:8200:9: error: no member named 'ops_func' in 'struct ftrace_ops'
> op->ops_func(op, FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER);
> ~~ ^
> kernel/trace/ftrace.c:8203:16: error: use of undeclared identifier 'direct_mutex'; did you mean 'event_mutex'?
> mutex_unlock(&direct_mutex);
> ^~~~~~~~~~~~
> event_mutex
> kernel/trace/trace.h:1523:21: note: 'event_mutex' declared here
> extern struct mutex event_mutex;
> ^
> 13 errors generated.
>
>
> vim +8082 kernel/trace/ftrace.c
>
> 8051
> 8052 /*
> 8053 * When registering ftrace_ops with IPMODIFY, it is necessary to make sure
> 8054 * it doesn't conflict with any direct ftrace_ops. If there is existing
> 8055 * direct ftrace_ops on a kernel function being patched, call
> 8056 * FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER on it to enable sharing.
> 8057 *
> 8058 * @ops: ftrace_ops being registered.
> 8059 *
> 8060 * Returns:
> 8061 * 0 - @ops does not have IPMODIFY or @ops itself is DIRECT, no
> 8062 * change needed;
> 8063 * 1 - @ops has IPMODIFY, hold direct_mutex;
> 8064 * -EBUSY - currently registered DIRECT ftrace_ops cannot share the
> 8065 * same function with IPMODIFY, abort the register.
> 8066 * -EAGAIN - cannot make changes to currently registered DIRECT
> 8067 * ftrace_ops due to rare race conditions. Should retry
> 8068 * later. This is needed to avoid potential deadlocks
> 8069 * on the DIRECT ftrace_ops side.
> 8070 */
> 8071 static int prepare_direct_functions_for_ipmodify(struct ftrace_ops *ops)
> 8072 __acquires(&direct_mutex)
> 8073 {
> 8074 struct ftrace_func_entry *entry;
> 8075 struct ftrace_hash *hash;
> 8076 struct ftrace_ops *op;
> 8077 int size, i, ret;
> 8078
> 8079 if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY))
> 8080 return 0;
> 8081
>> 8082 mutex_lock(&direct_mutex);
> 8083
>> 8084 hash = ops->func_hash->filter_hash;
> 8085 size = 1 << hash->size_bits;
> 8086 for (i = 0; i < size; i++) {
> 8087 hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
> 8088 unsigned long ip = entry->ip;
> 8089 bool found_op = false;
> 8090
> 8091 mutex_lock(&ftrace_lock);
> 8092 do_for_each_ftrace_op(op, ftrace_ops_list) {
> 8093 if (!(op->flags & FTRACE_OPS_FL_DIRECT))
> 8094 continue;
>> 8095 if (ops_references_ip(op, ip)) {
> 8096 found_op = true;
> 8097 break;
> 8098 }
> 8099 } while_for_each_ftrace_op(op);
> 8100 mutex_unlock(&ftrace_lock);
> 8101
> 8102 if (found_op) {
>> 8103 if (!op->ops_func) {
> 8104 ret = -EBUSY;
> 8105 goto err_out;
> 8106 }
> 8107 ret = op->ops_func(op, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER);
> 8108 if (ret)
> 8109 goto err_out;
> 8110 }
> 8111 }
> 8112 }
> 8113
> 8114 /*
> 8115 * Didn't find any overlap with direct ftrace_ops, or the direct
> 8116 * function can share with ipmodify. Hold direct_mutex to make sure
> 8117 * this doesn't change until we are done.
> 8118 */
> 8119 return 1;
> 8120
> 8121 err_out:
> 8122 mutex_unlock(&direct_mutex);
> 8123 return ret;
> 8124 }
> 8125
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp
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