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FAILED: patch "[PATCH] Revert "tracing: Add "(fault)" name injection to kernel" failed to apply to 6.1-stable tree

PATCH [email protected] 1 participant 1 message Jul 21, 2023

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The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 4ed8f337dee32df71435689c19d22e4ee846e15a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023072146-thus-data-323d@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

4ed8f337dee3 ("Revert "tracing: Add "(fault)" name injection to kernel probes"") 00cf3d672a9d ("tracing: Allow synthetic events to pass around stacktraces")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 4ed8f337dee32df71435689c19d22e4ee846e15a Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <[email protected]>
Date: Tue, 11 Jul 2023 23:15:57 +0900
Subject: [PATCH] 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/ open here
Link https://lore.kernel.org/all/[email protected]/ open here
Cc [email protected]
Cc Andrew Morton <[email protected]>
Cc Tom Zanussi <[email protected]>
Signed-off-by Masami Hiramatsu (Google) <[email protected]>
Reviewed-by Steven Rostedt (Google) <[email protected]>
kernel/trace/trace.h +2 -0
index 79bdefe9261b..eee1f3ca4749 100644
@@ -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
kernel/trace/trace_probe.c +1 -1
index 2d2616678295..591399ddcee5 100644
@@ -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));
kernel/trace/trace_probe_kernel.h +6 -25
index c4e1d4c03a85..6deae2ce34f8 100644
@@ -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;
 }