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authorLinus Torvalds <torvalds@linux-foundation.org>2020-08-03 14:25:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-03 14:25:40 -0700
commit5ece08178d6567db5ef0090b1ae7f795c3c36161 (patch)
treee052c9473b8ec03b278d74e829da21a3c33a41a6 /include
parentc8e69391d046a6acaa6a4cf72f9952ecd77d3085 (diff)
parentd19e789f068b3d633cbac430764962f404198022 (diff)
Merge tag 'core-headers-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull header cleanup from Ingo Molnar: "Separate out the instrumentation_begin()/end() bits from compiler.h" * tag 'core-headers-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: compiler.h: Move instrumentation_begin()/end() to new <linux/instrumentation.h> header
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/bug.h1
-rw-r--r--include/linux/compiler.h53
-rw-r--r--include/linux/context_tracking.h2
-rw-r--r--include/linux/instrumentation.h57
4 files changed, 60 insertions, 53 deletions
diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index c94e33ae3e7b..18b0f4eee8cb 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -3,6 +3,7 @@
#define _ASM_GENERIC_BUG_H
#include <linux/compiler.h>
+#include <linux/instrumentation.h>
#define CUT_HERE "------------[ cut here ]------------\n"
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 59f7194fdf08..6810d80acb0b 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -120,65 +120,12 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
/* Annotate a C jump table to allow objtool to follow the code flow */
#define __annotate_jump_table __section(.rodata..c_jump_table)
-#ifdef CONFIG_DEBUG_ENTRY
-/* Begin/end of an instrumentation safe region */
-#define instrumentation_begin() ({ \
- asm volatile("%c0: nop\n\t" \
- ".pushsection .discard.instr_begin\n\t" \
- ".long %c0b - .\n\t" \
- ".popsection\n\t" : : "i" (__COUNTER__)); \
-})
-
-/*
- * Because instrumentation_{begin,end}() can nest, objtool validation considers
- * _begin() a +1 and _end() a -1 and computes a sum over the instructions.
- * When the value is greater than 0, we consider instrumentation allowed.
- *
- * There is a problem with code like:
- *
- * noinstr void foo()
- * {
- * instrumentation_begin();
- * ...
- * if (cond) {
- * instrumentation_begin();
- * ...
- * instrumentation_end();
- * }
- * bar();
- * instrumentation_end();
- * }
- *
- * If instrumentation_end() would be an empty label, like all the other
- * annotations, the inner _end(), which is at the end of a conditional block,
- * would land on the instruction after the block.
- *
- * If we then consider the sum of the !cond path, we'll see that the call to
- * bar() is with a 0-value, even though, we meant it to happen with a positive
- * value.
- *
- * To avoid this, have _end() be a NOP instruction, this ensures it will be
- * part of the condition block and does not escape.
- */
-#define instrumentation_end() ({ \
- asm volatile("%c0: nop\n\t" \
- ".pushsection .discard.instr_end\n\t" \
- ".long %c0b - .\n\t" \
- ".popsection\n\t" : : "i" (__COUNTER__)); \
-})
-#endif /* CONFIG_DEBUG_ENTRY */
-
#else
#define annotate_reachable()
#define annotate_unreachable()
#define __annotate_jump_table
#endif
-#ifndef instrumentation_begin
-#define instrumentation_begin() do { } while(0)
-#define instrumentation_end() do { } while(0)
-#endif
-
#ifndef ASM_UNREACHABLE
# define ASM_UNREACHABLE
#endif
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index 981b880d5b60..d53cd331c4dd 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -5,6 +5,8 @@
#include <linux/sched.h>
#include <linux/vtime.h>
#include <linux/context_tracking_state.h>
+#include <linux/instrumentation.h>
+
#include <asm/ptrace.h>
diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
new file mode 100644
index 000000000000..93e2ad67fc10
--- /dev/null
+++ b/include/linux/instrumentation.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_INSTRUMENTATION_H
+#define __LINUX_INSTRUMENTATION_H
+
+#if defined(CONFIG_DEBUG_ENTRY) && defined(CONFIG_STACK_VALIDATION)
+
+/* Begin/end of an instrumentation safe region */
+#define instrumentation_begin() ({ \
+ asm volatile("%c0: nop\n\t" \
+ ".pushsection .discard.instr_begin\n\t" \
+ ".long %c0b - .\n\t" \
+ ".popsection\n\t" : : "i" (__COUNTER__)); \
+})
+
+/*
+ * Because instrumentation_{begin,end}() can nest, objtool validation considers
+ * _begin() a +1 and _end() a -1 and computes a sum over the instructions.
+ * When the value is greater than 0, we consider instrumentation allowed.
+ *
+ * There is a problem with code like:
+ *
+ * noinstr void foo()
+ * {
+ * instrumentation_begin();
+ * ...
+ * if (cond) {
+ * instrumentation_begin();
+ * ...
+ * instrumentation_end();
+ * }
+ * bar();
+ * instrumentation_end();
+ * }
+ *
+ * If instrumentation_end() would be an empty label, like all the other
+ * annotations, the inner _end(), which is at the end of a conditional block,
+ * would land on the instruction after the block.
+ *
+ * If we then consider the sum of the !cond path, we'll see that the call to
+ * bar() is with a 0-value, even though, we meant it to happen with a positive
+ * value.
+ *
+ * To avoid this, have _end() be a NOP instruction, this ensures it will be
+ * part of the condition block and does not escape.
+ */
+#define instrumentation_end() ({ \
+ asm volatile("%c0: nop\n\t" \
+ ".pushsection .discard.instr_end\n\t" \
+ ".long %c0b - .\n\t" \
+ ".popsection\n\t" : : "i" (__COUNTER__)); \
+})
+#else
+# define instrumentation_begin() do { } while(0)
+# define instrumentation_end() do { } while(0)
+#endif
+
+#endif /* __LINUX_INSTRUMENTATION_H */