From d5f28bb1ce04636b285726ee2a5afa3a514025f4 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Sat, 8 Jul 2023 01:38:03 +0900 Subject: fprobes: Add a comment why fprobe_kprobe_handler exits if kprobe is running Add a comment the reason why fprobe_kprobe_handler() exits if any other kprobe is running. Link: https://lore.kernel.org/all/168874788299.159442.2485957441413653858.stgit@devnote2/ Suggested-by: Steven Rostedt Link: https://lore.kernel.org/all/20230706120916.3c6abf15@gandalf.local.home/ Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google) --- kernel/trace/fprobe.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index 2571f7f3d5f2..59321d22f43e 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -100,6 +100,12 @@ static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip, return; } + /* + * This user handler is shared with other kprobes and is not expected to be + * called recursively. So if any other kprobe handler is running, this will + * exit as kprobe does. See the section 'Share the callbacks with kprobes' + * in Documentation/trace/fprobe.rst for more information. + */ if (unlikely(kprobe_running())) { fp->nmissed++; goto recursion_unlock; -- cgit From 66bcf65d6cf0ca6540e2341e88ee7ef02dbdda08 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 11 Jul 2023 23:15:29 +0900 Subject: tracing/probes: Fix to avoid double count of the string length on the array If an array is specified with the ustring or symstr, the length of the strings are accumlated on both of 'ret' and 'total', which means the length is double counted. Just set the length to the 'ret' value for avoiding double counting. Link: https://lore.kernel.org/all/168908492917.123124.15076463491122036025.stgit@devnote2/ Reported-by: Dan Carpenter Closes: https://lore.kernel.org/all/8819b154-2ba1-43c3-98a2-cbde20892023@moroto.mountain/ Fixes: 88903c464321 ("tracing/probe: Add ustring type for user-space string") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google) --- kernel/trace/trace_probe_tmpl.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h index 00707630788d..4735c5cb76fa 100644 --- a/kernel/trace/trace_probe_tmpl.h +++ b/kernel/trace/trace_probe_tmpl.h @@ -156,11 +156,11 @@ stage3: code++; goto array; case FETCH_OP_ST_USTRING: - ret += fetch_store_strlen_user(val + code->offset); + ret = fetch_store_strlen_user(val + code->offset); code++; goto array; case FETCH_OP_ST_SYMSTR: - ret += fetch_store_symstrlen(val + code->offset); + ret = fetch_store_symstrlen(val + code->offset); code++; goto array; default: -- cgit From b41326b5e0f82e93592c4366359917b5d67b529f Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 11 Jul 2023 23:15:38 +0900 Subject: tracing/probes: Fix not to count error code to total length Fix not to count the error code (which is minus value) to the total used length of array, because it can mess up the return code of process_fetch_insn_bottom(). Also clear the 'ret' value because it will be used for calculating next data_loc entry. Link: https://lore.kernel.org/all/168908493827.123124.2175257289106364229.stgit@devnote2/ Reported-by: Dan Carpenter Closes: https://lore.kernel.org/all/8819b154-2ba1-43c3-98a2-cbde20892023@moroto.mountain/ Fixes: 9b960a38835f ("tracing: probeevent: Unify fetch_insn processing common part") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google) --- kernel/trace/trace_probe_tmpl.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel') diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h index 4735c5cb76fa..ed9d57c6b041 100644 --- a/kernel/trace/trace_probe_tmpl.h +++ b/kernel/trace/trace_probe_tmpl.h @@ -204,6 +204,8 @@ stage3: array: /* the last stage: Loop on array */ if (code->op == FETCH_OP_LP_ARRAY) { + if (ret < 0) + ret = 0; total += ret; if (++i < code->param) { code = s3; -- cgit From e38e2c6a9efc435f9de344b7c91f7697e01b47d5 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 11 Jul 2023 23:15:48 +0900 Subject: tracing/probes: Fix to update dynamic data counter if fetcharg uses it Fix to update dynamic data counter ('dyndata') and max length ('maxlen') only if the fetcharg uses the dynamic data. Also get out arg->dynamic from unlikely(). This makes dynamic data address wrong if process_fetch_insn() returns error on !arg->dynamic case. Link: https://lore.kernel.org/all/168908494781.123124.8160245359962103684.stgit@devnote2/ Suggested-by: Steven Rostedt Link: https://lore.kernel.org/all/20230710233400.5aaf024e@gandalf.local.home/ Fixes: 9178412ddf5a ("tracing: probeevent: Return consumed bytes of dynamic area") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google) --- kernel/trace/trace_probe_tmpl.h | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h index ed9d57c6b041..185da001f4c3 100644 --- a/kernel/trace/trace_probe_tmpl.h +++ b/kernel/trace/trace_probe_tmpl.h @@ -267,11 +267,13 @@ store_trace_args(void *data, struct trace_probe *tp, void *rec, if (unlikely(arg->dynamic)) *dl = make_data_loc(maxlen, dyndata - base); ret = process_fetch_insn(arg->code, rec, dl, base); - if (unlikely(ret < 0 && arg->dynamic)) { - *dl = make_data_loc(0, dyndata - base); - } else { - dyndata += ret; - maxlen -= ret; + if (arg->dynamic) { + if (unlikely(ret < 0)) { + *dl = make_data_loc(0, dyndata - base); + } else { + dyndata += ret; + maxlen -= ret; + } } } } -- cgit From 4ed8f337dee32df71435689c19d22e4ee846e15a Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 11 Jul 2023 23:15:57 +0900 Subject: Revert "tracing: Add "(fault)" name injection to kernel probes" This reverts commit 2e9906f84fc7c99388bb7123ade167250d50f1c0. It was turned out that commit 2e9906f84fc7 ("tracing: Add "(fault)" name injection to kernel probes") did not work correctly and probe events still show just '(fault)' (instead of '"(fault)"'). Also, current '(fault)' is more explicit that it faulted. This also moves FAULT_STRING macro to trace.h so that synthetic event can keep using it, and uses it in trace_probe.c too. Link: https://lore.kernel.org/all/168908495772.123124.1250788051922100079.stgit@devnote2/ Link: https://lore.kernel.org/all/20230706230642.3793a593@rorschach.local.home/ Cc: stable@vger.kernel.org Cc: Andrew Morton Cc: Tom Zanussi Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google) --- kernel/trace/trace.h | 2 ++ kernel/trace/trace_probe.c | 2 +- kernel/trace/trace_probe_kernel.h | 31 ++++++------------------------- 3 files changed, 9 insertions(+), 26 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 79bdefe9261b..eee1f3ca4749 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -113,6 +113,8 @@ enum trace_type { #define MEM_FAIL(condition, fmt, ...) \ DO_ONCE_LITE_IF(condition, pr_err, "ERROR: " fmt, ##__VA_ARGS__) +#define FAULT_STRING "(fault)" + #define HIST_STACKTRACE_DEPTH 16 #define HIST_STACKTRACE_SIZE (HIST_STACKTRACE_DEPTH * sizeof(unsigned long)) #define HIST_STACKTRACE_SKIP 5 diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c index 2d2616678295..591399ddcee5 100644 --- a/kernel/trace/trace_probe.c +++ b/kernel/trace/trace_probe.c @@ -65,7 +65,7 @@ int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent) int len = *(u32 *)data >> 16; if (!len) - trace_seq_puts(s, "(fault)"); + trace_seq_puts(s, FAULT_STRING); else trace_seq_printf(s, "\"%s\"", (const char *)get_loc_data(data, ent)); diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h index c4e1d4c03a85..6deae2ce34f8 100644 --- a/kernel/trace/trace_probe_kernel.h +++ b/kernel/trace/trace_probe_kernel.h @@ -2,8 +2,6 @@ #ifndef __TRACE_PROBE_KERNEL_H_ #define __TRACE_PROBE_KERNEL_H_ -#define FAULT_STRING "(fault)" - /* * This depends on trace_probe.h, but can not include it due to * the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c. @@ -15,16 +13,8 @@ static nokprobe_inline int fetch_store_strlen_user(unsigned long addr) { const void __user *uaddr = (__force const void __user *)addr; - int ret; - ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE); - /* - * strnlen_user_nofault returns zero on fault, insert the - * FAULT_STRING when that occurs. - */ - if (ret <= 0) - return strlen(FAULT_STRING) + 1; - return ret; + return strnlen_user_nofault(uaddr, MAX_STRING_SIZE); } /* Return the length of string -- including null terminal byte */ @@ -44,18 +34,7 @@ fetch_store_strlen(unsigned long addr) len++; } while (c && ret == 0 && len < MAX_STRING_SIZE); - /* For faults, return enough to hold the FAULT_STRING */ - return (ret < 0) ? strlen(FAULT_STRING) + 1 : len; -} - -static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len) -{ - if (ret >= 0) { - *(u32 *)dest = make_data_loc(ret, __dest - base); - } else { - strscpy(__dest, FAULT_STRING, len); - ret = strlen(__dest) + 1; - } + return (ret < 0) ? ret : len; } /* @@ -76,7 +55,8 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base) __dest = get_loc_data(dest, base); ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); - set_data_loc(ret, dest, __dest, base, maxlen); + if (ret >= 0) + *(u32 *)dest = make_data_loc(ret, __dest - base); return ret; } @@ -107,7 +87,8 @@ fetch_store_string(unsigned long addr, void *dest, void *base) * probing. */ ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); - set_data_loc(ret, dest, __dest, base, maxlen); + if (ret >= 0) + *(u32 *)dest = make_data_loc(ret, __dest - base); return ret; } -- cgit From 797311bce5c2ac90b8d65e357603cfd410d36ebb Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Tue, 11 Jul 2023 23:16:07 +0900 Subject: tracing/probes: Fix to record 0-length data_loc in fetch_store_string*() if fails Fix to record 0-length data to data_loc in fetch_store_string*() if it fails to get the string data. Currently those expect that the data_loc is updated by store_trace_args() if it returns the error code. However, that does not work correctly if the argument is an array of strings. In that case, store_trace_args() only clears the first entry of the array (which may have no error) and leaves other entries. So it should be cleared by fetch_store_string*() itself. Also, 'dyndata' and 'maxlen' in store_trace_args() should be updated only if it is used (ret > 0 and argument is a dynamic data.) Link: https://lore.kernel.org/all/168908496683.123124.4761206188794205601.stgit@devnote2/ Fixes: 40b53b771806 ("tracing: probeevent: Add array type support") Cc: stable@vger.kernel.org Reviewed-by: Steven Rostedt (Google) Signed-off-by: Masami Hiramatsu (Google) --- kernel/trace/trace_probe_kernel.h | 13 +++++++++---- kernel/trace/trace_probe_tmpl.h | 10 +++------- kernel/trace/trace_uprobe.c | 3 ++- 3 files changed, 14 insertions(+), 12 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h index 6deae2ce34f8..bb723eefd7b7 100644 --- a/kernel/trace/trace_probe_kernel.h +++ b/kernel/trace/trace_probe_kernel.h @@ -37,6 +37,13 @@ fetch_store_strlen(unsigned long addr) return (ret < 0) ? ret : len; } +static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base) +{ + if (ret < 0) + ret = 0; + *(u32 *)dest = make_data_loc(ret, __dest - base); +} + /* * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf * with max length and relative data location. @@ -55,8 +62,7 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base) __dest = get_loc_data(dest, base); ret = strncpy_from_user_nofault(__dest, uaddr, maxlen); - if (ret >= 0) - *(u32 *)dest = make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base); return ret; } @@ -87,8 +93,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base) * probing. */ ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); - if (ret >= 0) - *(u32 *)dest = make_data_loc(ret, __dest - base); + set_data_loc(ret, dest, __dest, base); return ret; } diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h index 185da001f4c3..3935b347f874 100644 --- a/kernel/trace/trace_probe_tmpl.h +++ b/kernel/trace/trace_probe_tmpl.h @@ -267,13 +267,9 @@ store_trace_args(void *data, struct trace_probe *tp, void *rec, if (unlikely(arg->dynamic)) *dl = make_data_loc(maxlen, dyndata - base); ret = process_fetch_insn(arg->code, rec, dl, base); - if (arg->dynamic) { - if (unlikely(ret < 0)) { - *dl = make_data_loc(0, dyndata - base); - } else { - dyndata += ret; - maxlen -= ret; - } + if (arg->dynamic && likely(ret > 0)) { + dyndata += ret; + maxlen -= ret; } } } diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 8b92e34ff0c8..7b47e9a2c010 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -170,7 +170,8 @@ fetch_store_string(unsigned long addr, void *dest, void *base) */ ret++; *(u32 *)dest = make_data_loc(ret, (void *)dst - base); - } + } else + *(u32 *)dest = make_data_loc(0, (void *)dst - base); return ret; } -- cgit