selftests/rseq: Fix: work-around asm goto compiler bugs

commit b53823f upstream. gcc and clang each have their own compiler bugs with respect to asm goto. Implement a work-around for compiler versions known to have those bugs. gcc prior to 4.8.2 miscompiles asm goto. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 gcc prior to 8.1.0 miscompiles asm goto at O1. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908 clang prior to version 13.0.1 miscompiles asm goto at O2. llvm/llvm-project#52735 Work around these issues by adding a volatile inline asm with memory clobber in the fallthrough after the asm goto and at each label target. Emit this for all compilers in case other similar issues are found in the future. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220124171253.22072-14-mathieu.desnoyers@efficios.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xanmod · Jul 7, 2022 · a4312e2 · a4312e2
1 parent 7e1a0a9
commit a4312e2
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Showing 7 changed files with 245 additions and 6 deletions.
diff --git a/tools/testing/selftests/rseq/compiler.h b/tools/testing/selftests/rseq/compiler.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: LGPL-2.1-only OR MIT */
+/*
+ * rseq/compiler.h
+ *
+ * Work-around asm goto compiler bugs.
+ *
+ * (C) Copyright 2021 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#ifndef RSEQ_COMPILER_H
+#define RSEQ_COMPILER_H
+
+/*
+ * gcc prior to 4.8.2 miscompiles asm goto.
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
+ *
+ * gcc prior to 8.1.0 miscompiles asm goto at O1.
+ * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103908
+ *
+ * clang prior to version 13.0.1 miscompiles asm goto at O2.
+ * https://github.com/llvm/llvm-project/issues/52735
+ *
+ * Work around these issues by adding a volatile inline asm with
+ * memory clobber in the fallthrough after the asm goto and at each
+ * label target.  Emit this for all compilers in case other similar
+ * issues are found in the future.
+ */
+#define rseq_after_asm_goto()	asm volatile ("" : : : "memory")
+
+#endif  /* RSEQ_COMPILER_H_ */
diff --git a/tools/testing/selftests/rseq/rseq-arm.h b/tools/testing/selftests/rseq/rseq-arm.h
@@ -195,16 +195,21 @@ int rseq_cmpeqv_storev(intptr_t *v, intptr_t expect, intptr_t newv, int cpu)
 		  , error1, error2
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -263,16 +268,21 @@ int rseq_cmpnev_storeoffp_load(intptr_t *v, intptr_t expectnot,
 		  , error1, error2
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -317,12 +327,15 @@ int rseq_addv(intptr_t *v, intptr_t count, int cpu)
 		  , error1
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 #endif
 }
@@ -384,16 +397,21 @@ int rseq_cmpeqv_trystorev_storev(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -456,16 +474,21 @@ int rseq_cmpeqv_trystorev_storev_release(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -532,18 +555,24 @@ int rseq_cmpeqv_cmpeqv_storev(intptr_t *v, intptr_t expect,
 		  , error1, error2, error3
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("1st expected value comparison failed");
 error3:
+	rseq_after_asm_goto();
 	rseq_bug("2nd expected value comparison failed");
 #endif
 }
@@ -652,16 +681,21 @@ int rseq_cmpeqv_trymemcpy_storev(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -771,16 +805,21 @@ int rseq_cmpeqv_trymemcpy_storev_release(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }

diff --git a/tools/testing/selftests/rseq/rseq-arm64.h b/tools/testing/selftests/rseq/rseq-arm64.h
@@ -242,17 +242,21 @@ int rseq_cmpeqv_storev(intptr_t *v, intptr_t expect, intptr_t newv, int cpu)
 		  , error1, error2
 #endif
 	);
-
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -300,16 +304,21 @@ int rseq_cmpnev_storeoffp_load(intptr_t *v, intptr_t expectnot,
 		  , error1, error2
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -348,12 +357,15 @@ int rseq_addv(intptr_t *v, intptr_t count, int cpu)
 		  , error1
 #endif
 	);
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 #endif
 }
@@ -402,17 +414,21 @@ int rseq_cmpeqv_trystorev_storev(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
-
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -461,17 +477,21 @@ int rseq_cmpeqv_trystorev_storev_release(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
-
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -522,19 +542,24 @@ int rseq_cmpeqv_cmpeqv_storev(intptr_t *v, intptr_t expect,
 		  , error1, error2, error3
 #endif
 	);
-
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 error3:
+	rseq_after_asm_goto();
 	rseq_bug("2nd expected value comparison failed");
 #endif
 }
@@ -584,17 +609,21 @@ int rseq_cmpeqv_trymemcpy_storev(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
-
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }
@@ -644,17 +673,21 @@ int rseq_cmpeqv_trymemcpy_storev_release(intptr_t *v, intptr_t expect,
 		  , error1, error2
 #endif
 	);
-
+	rseq_after_asm_goto();
 	return 0;
 abort:
+	rseq_after_asm_goto();
 	RSEQ_INJECT_FAILED
 	return -1;
 cmpfail:
+	rseq_after_asm_goto();
 	return 1;
 #ifdef RSEQ_COMPARE_TWICE
 error1:
+	rseq_after_asm_goto();
 	rseq_bug("cpu_id comparison failed");
 error2:
+	rseq_after_asm_goto();
 	rseq_bug("expected value comparison failed");
 #endif
 }