[PATCH v7 7/8] aarch64: Add rseq_load32_load32_relaxed

[Michael Jeanson <mjeanson@efficios.com>]

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

Implement rseq_load32_load32_relaxed() for the aarch64 architecture.
This static inline function implements a rseq critical section to load
two 32-bit integer values atomically with respect to preemption and
signal delivery.

This implementation is imported from the librseq project.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
 .../unix/sysv/linux/aarch64/rseq-internal.h   | 173 ++++++++++++++++++
 1 file changed, 173 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/aarch64/rseq-internal.h

diff --git a/sysdeps/unix/sysv/linux/aarch64/rseq-internal.h b/sysdeps/unix/sysv/linux/aarch64/rseq-internal.h
new file mode 100644
index 0000000000..3c03f67dbe
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/rseq-internal.h
@@ -0,0 +1,173 @@
+/* Restartable Sequences internal API. aarch64 macros.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <sysdeps/unix/sysv/linux/rseq-internal.h>
+
+#define RSEQ_ASM_TMP_REG32	"w15"
+#define RSEQ_ASM_TMP_REG	"x15"
+#define RSEQ_ASM_TMP_REG_2	"x14"
+
+#define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, start_ip,		\
+				post_commit_offset, abort_ip)			\
+	"	.pushsection	__rseq_cs, \"aw\"\n"				\
+	"	.balign	32\n"							\
+	__rseq_str(label) ":\n"							\
+	"	.long	" __rseq_str(version) ", " __rseq_str(flags) "\n"	\
+	"	.quad	" __rseq_str(start_ip) ", "				\
+			  __rseq_str(post_commit_offset) ", "			\
+			  __rseq_str(abort_ip) "\n"				\
+	"	.popsection\n\t"						\
+	"	.pushsection __rseq_cs_ptr_array, \"aw\"\n"				\
+	"	.quad " __rseq_str(label) "b\n"					\
+	"	.popsection\n"
+
+#define RSEQ_ASM_DEFINE_TABLE(label, start_ip, post_commit_ip, abort_ip)	\
+	__RSEQ_ASM_DEFINE_TABLE(label, 0x0, 0x0, start_ip,			\
+				(post_commit_ip - start_ip), abort_ip)
+
+/*
+ * Exit points of a rseq critical section consist of all instructions outside
+ * of the critical section where a critical section can either branch to or
+ * reach through the normal course of its execution. The abort IP and the
+ * post-commit IP are already part of the __rseq_cs section and should not be
+ * explicitly defined as additional exit points. Knowing all exit points is
+ * useful to assist debuggers stepping over the critical section.
+ */
+#define RSEQ_ASM_DEFINE_EXIT_POINT(start_ip, exit_ip)				\
+	"	.pushsection __rseq_exit_point_array, \"aw\"\n"			\
+	"	.quad " __rseq_str(start_ip) ", " __rseq_str(exit_ip) "\n"	\
+	"	.popsection\n"
+
+#define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs)			\
+	"	adrp	" RSEQ_ASM_TMP_REG ", " __rseq_str(cs_label) "\n"	\
+	"	add	" RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG		\
+			", :lo12:" __rseq_str(cs_label) "\n"			\
+	"	str	" RSEQ_ASM_TMP_REG ", %[" __rseq_str(rseq_cs) "]\n"	\
+	__rseq_str(label) ":\n"
+
+#define RSEQ_ASM_DEFINE_ABORT(label, abort_label)				\
+	"	b	222f\n"							\
+	"	.inst 	"	__rseq_str(RSEQ_SIG_CODE) "\n"			\
+	__rseq_str(label) ":\n"							\
+	"	b	%l[" __rseq_str(abort_label) "]\n"			\
+	"222:\n"
+
+#define RSEQ_ASM_OP_STORE(value, var)						\
+	"	str	%[" __rseq_str(value) "], %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_STORE_RELEASE(value, var)					\
+	"	stlr	%[" __rseq_str(value) "], %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_FINAL_STORE(value, var, post_commit_label)			\
+	RSEQ_ASM_OP_STORE(value, var)						\
+	__rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_FINAL_STORE_RELEASE(value, var, post_commit_label)		\
+	RSEQ_ASM_OP_STORE_RELEASE(value, var)					\
+	__rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_CMPEQ(var, expect, label)					\
+	"	ldr	" RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n"		\
+	"	sub	" RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG		\
+			", %[" __rseq_str(expect) "]\n"				\
+	"	cbnz	" RSEQ_ASM_TMP_REG ", " __rseq_str(label) "\n"
+
+#define RSEQ_ASM_OP_CMPEQ32(var, expect, label)					\
+	"	ldr	" RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n"	\
+	"	sub	" RSEQ_ASM_TMP_REG32 ", " RSEQ_ASM_TMP_REG32		\
+			", %w[" __rseq_str(expect) "]\n"			\
+	"	cbnz	" RSEQ_ASM_TMP_REG32 ", " __rseq_str(label) "\n"
+
+#define RSEQ_ASM_OP_CMPNE(var, expect, label)					\
+	"	ldr	" RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n"		\
+	"	sub	" RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG		\
+			", %[" __rseq_str(expect) "]\n"				\
+	"	cbz	" RSEQ_ASM_TMP_REG ", " __rseq_str(label) "\n"
+
+#define RSEQ_ASM_CMP_CPU_ID(cpu_id, current_cpu_id, label)			\
+	RSEQ_ASM_OP_CMPEQ32(current_cpu_id, cpu_id, label)
+
+#define RSEQ_ASM_OP_R_LOAD(var)							\
+	"	ldr	" RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_STORE(var)						\
+	"	str	" RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_LOAD32(var)						\
+	"	ldr	" RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_STORE32(var)						\
+	"	str	" RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n"
+
+#define RSEQ_ASM_OP_R_LOAD_OFF(offset)						\
+	"	ldr	" RSEQ_ASM_TMP_REG ", [" RSEQ_ASM_TMP_REG		\
+			", %[" __rseq_str(offset) "]]\n"
+
+#define RSEQ_ASM_OP_R_ADD(count)						\
+	"	add	" RSEQ_ASM_TMP_REG ", " RSEQ_ASM_TMP_REG		\
+			", %[" __rseq_str(count) "]\n"
+
+#define RSEQ_ASM_OP_R_FINAL_STORE(var, post_commit_label)			\
+	"	str	" RSEQ_ASM_TMP_REG ", %[" __rseq_str(var) "]\n"		\
+	__rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_R_FINAL_STORE32(var, post_commit_label)			\
+	"	str	" RSEQ_ASM_TMP_REG32 ", %[" __rseq_str(var) "]\n"	\
+	__rseq_str(post_commit_label) ":\n"
+
+#define RSEQ_ASM_OP_R_BAD_MEMCPY(dst, src, len)					\
+	"	cbz	%[" __rseq_str(len) "], 333f\n"				\
+	"	mov	" RSEQ_ASM_TMP_REG_2 ", %[" __rseq_str(len) "]\n"	\
+	"222:	sub	" RSEQ_ASM_TMP_REG_2 ", " RSEQ_ASM_TMP_REG_2 ", #1\n"	\
+	"	ldrb	" RSEQ_ASM_TMP_REG32 ", [%[" __rseq_str(src) "]"	\
+			", " RSEQ_ASM_TMP_REG_2 "]\n"				\
+	"	strb	" RSEQ_ASM_TMP_REG32 ", [%[" __rseq_str(dst) "]"	\
+			", " RSEQ_ASM_TMP_REG_2 "]\n"				\
+	"	cbnz	" RSEQ_ASM_TMP_REG_2 ", 222b\n"				\
+	"333:\n"
+
+/*
+ * Load @src1 (32-bit) into @dst1 and load @src2 (32-bit) into @dst2.
+ */
+#define RSEQ_HAS_LOAD32_LOAD32_RELAXED 1
+static __always_inline int
+rseq_load32_load32_relaxed(uint32_t *dst1, uint32_t *src1,
+			       uint32_t *dst2, uint32_t *src2)
+{
+	__asm__ __volatile__ goto (
+		RSEQ_ASM_DEFINE_TABLE(1, 2f, 3f, 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(2, 1b, rseq_cs)
+		RSEQ_ASM_OP_R_LOAD32(src1)
+		RSEQ_ASM_OP_R_STORE32(dst1)
+		RSEQ_ASM_OP_R_LOAD32(src2)
+		RSEQ_ASM_OP_R_FINAL_STORE32(dst2, 3)
+		RSEQ_ASM_DEFINE_ABORT(4, abort)
+		: /* gcc asm goto does not allow outputs */
+		: [rseq_cs]		"m" (rseq_get_area()->rseq_cs),
+		  [dst1]		"Qo" (*dst1),
+		  [dst2]		"Qo" (*dst2),
+		  [src1]		"Qo" (*src1),
+		  [src2]		"Qo" (*src2)
+		: "memory", RSEQ_ASM_TMP_REG
+		: abort
+	);
+	rseq_after_asm_goto();
+	return 0;
+abort:
+	rseq_after_asm_goto();
+	return -1;
+}
-- 
2.34.1