[v2] aarch64: vdso: Wire up getrandom() vDSO implementation

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a2f8ff354ca6..7f7424d1b3b8 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -262,6 +262,7 @@  config ARM64
 	select TRACE_IRQFLAGS_NMI_SUPPORT
 	select HAVE_SOFTIRQ_ON_OWN_STACK
 	select USER_STACKTRACE_SUPPORT
+	select VDSO_GETRANDOM
 	help
 	  ARM 64-bit (AArch64) Linux support.
 
diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h
index 4305995c8f82..18407b757c95 100644
--- a/arch/arm64/include/asm/vdso.h
+++ b/arch/arm64/include/asm/vdso.h
@@ -16,6 +16,12 @@ 
 
 #ifndef __ASSEMBLY__
 
+enum vvar_pages {
+	VVAR_DATA_PAGE_OFFSET,
+	VVAR_TIMENS_PAGE_OFFSET,
+	VVAR_NR_PAGES,
+};
+
 #include <generated/vdso-offsets.h>
 
 #define VDSO_SYMBOL(base, name)						   \
diff --git a/arch/arm64/include/asm/vdso/getrandom.h b/arch/arm64/include/asm/vdso/getrandom.h
new file mode 100644
index 000000000000..fca66ba49d4c
--- /dev/null
+++ b/arch/arm64/include/asm/vdso/getrandom.h
@@ -0,0 +1,49 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_VDSO_GETRANDOM_H
+#define __ASM_VDSO_GETRANDOM_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/vdso.h>
+#include <asm/unistd.h>
+#include <vdso/datapage.h>
+
+/**
+ * getrandom_syscall - Invoke the getrandom() syscall.
+ * @buffer:	Destination buffer to fill with random bytes.
+ * @len:	Size of @buffer in bytes.
+ * @flags:	Zero or more GRND_* flags.
+ * Returns:	The number of random bytes written to @buffer, or a negative value indicating an error.
+ */
+static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, unsigned int _flags)
+{
+	register void *buffer asm ("x0") = _buffer;
+	register size_t len asm ("x1") = _len;
+	register unsigned int flags asm ("x2") = _flags;
+	register long ret asm ("x0");
+	register long nr asm ("x8") = __NR_getrandom;
+
+	asm volatile(
+	"       svc #0\n"
+	: "=r" (ret)
+	: "r" (buffer), "r" (len), "r" (flags), "r" (nr)
+	: "memory");
+
+	return ret;
+}
+
+static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data(void)
+{
+	/*
+	 * If a task belongs to a time namespace then a namespace the real
+	 * VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET.
+	 */
+	if (IS_ENABLED(CONFIG_TIME_NS) && _vdso_data->clock_mode == VDSO_CLOCKMODE_TIMENS)
+		return (void*)&_vdso_rng_data + VVAR_TIMENS_PAGE_OFFSET * PAGE_SIZE;
+	return &_vdso_rng_data;
+}
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __ASM_VDSO_GETRANDOM_H */
diff --git a/arch/arm64/include/asm/vdso/vsyscall.h b/arch/arm64/include/asm/vdso/vsyscall.h
index f94b1457c117..2a87f0e1b144 100644
--- a/arch/arm64/include/asm/vdso/vsyscall.h
+++ b/arch/arm64/include/asm/vdso/vsyscall.h
@@ -2,8 +2,11 @@ 
 #ifndef __ASM_VDSO_VSYSCALL_H
 #define __ASM_VDSO_VSYSCALL_H
 
+#define __VDSO_RND_DATA_OFFSET  480
+
 #ifndef __ASSEMBLY__
 
+#include <asm/vdso.h>
 #include <linux/timekeeper_internal.h>
 #include <vdso/datapage.h>
 
@@ -21,6 +24,13 @@  struct vdso_data *__arm64_get_k_vdso_data(void)
 }
 #define __arch_get_k_vdso_data __arm64_get_k_vdso_data
 
+static __always_inline
+struct vdso_rng_data *__arm64_get_k_vdso_rnd_data(void)
+{
+	return (void*)vdso_data + __VDSO_RND_DATA_OFFSET;
+}
+#define __arch_get_k_vdso_rng_data __arm64_get_k_vdso_rnd_data
+
 static __always_inline
 void __arm64_update_vsyscall(struct vdso_data *vdata, struct timekeeper *tk)
 {
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 89b6e7840002..706c9c3a7a50 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -34,12 +34,6 @@  enum vdso_abi {
 	VDSO_ABI_AA32,
 };
 
-enum vvar_pages {
-	VVAR_DATA_PAGE_OFFSET,
-	VVAR_TIMENS_PAGE_OFFSET,
-	VVAR_NR_PAGES,
-};
-
 struct vdso_abi_info {
 	const char *name;
 	const char *vdso_code_start;
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index d11da6461278..50246a38d6bd 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -9,7 +9,7 @@ 
 # Include the generic Makefile to check the built vdso.
 include $(srctree)/lib/vdso/Makefile
 
-obj-vdso := vgettimeofday.o note.o sigreturn.o
+obj-vdso := vgettimeofday.o note.o sigreturn.o vgetrandom.o vgetrandom-chacha.o
 
 # Build rules
 targets := $(obj-vdso) vdso.so vdso.so.dbg
@@ -40,13 +40,22 @@  CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
 				$(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \
 				$(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
 				-Wmissing-prototypes -Wmissing-declarations
+CFLAGS_REMOVE_vgetrandom.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
+			     $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \
+			     $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
+			     -Wmissing-prototypes -Wmissing-declarations
 
 CFLAGS_vgettimeofday.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables
+CFLAGS_vgetrandom.o = -O2 -mcmodel=tiny -fasynchronous-unwind-tables
 
 ifneq ($(c-gettimeofday-y),)
   CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
 endif
 
+ifneq ($(c-getrandom-y),)
+  CFLAGS_vgetrandom.o += -include $(c-getrandom-y)
+endif
+
 targets += vdso.lds
 CPPFLAGS_vdso.lds += -P -C -U$(ARCH)
 
diff --git a/arch/arm64/kernel/vdso/vdso b/arch/arm64/kernel/vdso/vdso
new file mode 120000
index 000000000000..233c7a26f6e5
--- /dev/null
+++ b/arch/arm64/kernel/vdso/vdso
@@ -0,0 +1 @@ 
+../../../arch/arm64/kernel/vdso
\ No newline at end of file
diff --git a/arch/arm64/kernel/vdso/vdso.lds.S b/arch/arm64/kernel/vdso/vdso.lds.S
index 45354f2ddf70..f204a9ddc833 100644
--- a/arch/arm64/kernel/vdso/vdso.lds.S
+++ b/arch/arm64/kernel/vdso/vdso.lds.S
@@ -11,7 +11,9 @@ 
 #include <linux/const.h>
 #include <asm/page.h>
 #include <asm/vdso.h>
+#include <asm/vdso/vsyscall.h>
 #include <asm-generic/vmlinux.lds.h>
+#include <vdso/datapage.h>
 
 OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64")
 OUTPUT_ARCH(aarch64)
@@ -19,6 +21,7 @@  OUTPUT_ARCH(aarch64)
 SECTIONS
 {
 	PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE);
+	PROVIDE(_vdso_rng_data = _vdso_data + __VDSO_RND_DATA_OFFSET);
 #ifdef CONFIG_TIME_NS
 	PROVIDE(_timens_data = _vdso_data + PAGE_SIZE);
 #endif
@@ -102,6 +105,7 @@  VERSION
 		__kernel_gettimeofday;
 		__kernel_clock_gettime;
 		__kernel_clock_getres;
+		__kernel_getrandom;
 	local: *;
 	};
 }
diff --git a/arch/arm64/kernel/vdso/vgetrandom-chacha.S b/arch/arm64/kernel/vdso/vgetrandom-chacha.S
new file mode 100644
index 000000000000..9ebf12a09c65
--- /dev/null
+++ b/arch/arm64/kernel/vdso/vgetrandom-chacha.S
@@ -0,0 +1,168 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/linkage.h>
+#include <asm/cache.h>
+#include <asm/assembler.h>
+
+	.text
+
+#define state0		v0
+#define state1		v1
+#define state2		v2
+#define state3		v3
+#define copy0		v4
+#define copy1		v5
+#define copy2		v6
+#define copy3		v7
+#define copy3_d		d7
+#define one_d		d16
+#define one_q		q16
+#define tmp		v17
+#define rot8		v18
+
+/*
+ * ARM64 ChaCha20 implementation meant for vDSO.  Produces a given positive
+ * number of blocks of output with nonce 0, taking an input key and 8-bytes
+ * counter.  Importantly does not spill to the stack.
+ *
+ * void __arch_chacha20_blocks_nostack(uint8_t *dst_bytes,
+ *				       const uint8_t *key,
+ * 				       uint32_t *counter,
+ *				       size_t nblocks)
+ *
+ * 	x0: output bytes
+ *	x1: 32-byte key input
+ *	x2: 8-byte counter input/output
+ *	x3: number of 64-byte block to write to output
+ */
+SYM_FUNC_START(__arch_chacha20_blocks_nostack)
+
+	/* copy0 = "expand 32-byte k" */
+	adr_l		x8, CTES
+	ld1		{copy0.4s}, [x8]
+	/* copy1,copy2 = key */
+	ld1		{ copy1.4s, copy2.4s }, [x1]
+	/* copy3 = counter || zero nonce  */
+	ldr		copy3_d, [x2]
+
+	adr_l		x8, ONE
+	ldr		one_q, [x8]
+
+	adr_l		x10, ROT8
+	ld1		{rot8.4s}, [x10]
+.Lblock:
+	/* copy state to auxiliary vectors for the final add after the permute.  */
+	mov		state0.16b, copy0.16b
+	mov		state1.16b, copy1.16b
+	mov		state2.16b, copy2.16b
+	mov		state3.16b, copy3.16b
+
+	mov		w4, 20
+.Lpermute:
+	/*
+	 * Permute one 64-byte block where the state matrix is stored in the four NEON
+	 * registers state0-state3.  It performs matrix operations on four words in parallel,
+	 * but requires shuffling to rearrange the words after each round.
+	 */
+
+.Ldoubleround:
+	/* state0 += state1, state3 = rotl32(state3 ^ state0, 16) */
+	add		state0.4s, state0.4s, state1.4s
+	eor		state3.16b, state3.16b, state0.16b
+	rev32		state3.8h, state3.8h
+
+	/* state2 += state3, state1 = rotl32(state1 ^ state2, 12) */
+	add		state2.4s, state2.4s, state3.4s
+	eor		tmp.16b, state1.16b, state2.16b
+	shl		state1.4s, tmp.4s, #12
+	sri		state1.4s, tmp.4s, #20
+
+	/* state0 += state1, state3 = rotl32(state3 ^ state0, 8) */
+	add		state0.4s, state0.4s, state1.4s
+	eor		state3.16b, state3.16b, state0.16b
+	tbl		state3.16b, {state3.16b}, rot8.16b
+
+	/* state2 += state3, state1 = rotl32(state1 ^ state2, 7) */
+	add		state2.4s, state2.4s, state3.4s
+	eor		tmp.16b, state1.16b, state2.16b
+	shl		state1.4s, tmp.4s, #7
+	sri		state1.4s, tmp.4s, #25
+
+	/* state1[0,1,2,3] = state1[1,2,3,0] */
+	ext		state1.16b, state1.16b, state1.16b, #4
+	/* state2[0,1,2,3] = state2[2,3,0,1] */
+	ext		state2.16b, state2.16b, state2.16b, #8
+	/* state3[0,1,2,3] = state3[1,2,3,0] */
+	ext		state3.16b, state3.16b, state3.16b, #12
+
+	/* state0 += state1, state3 = rotl32(state3 ^ state0, 16) */
+	add		state0.4s, state0.4s, state1.4s
+	eor		state3.16b, state3.16b, state0.16b
+	rev32		state3.8h, state3.8h
+
+	/* state2 += state3, state1 = rotl32(state1 ^ state2, 12) */
+	add		state2.4s, state2.4s, state3.4s
+	eor		tmp.16b, state1.16b, state2.16b
+	shl		state1.4s, tmp.4s, #12
+	sri		state1.4s, tmp.4s, #20
+
+	/* state0 += state1, state3 = rotl32(state3 ^ state0, 8) */
+	add		state0.4s, state0.4s, state1.4s
+	eor		state3.16b, state3.16b, state0.16b
+	tbl		state3.16b, {state3.16b}, rot8.16b
+
+	/* state2 += state3, state1 = rotl32(state1 ^ state2, 7) */
+	add		state2.4s, state2.4s, state3.4s
+	eor		tmp.16b, state1.16b, state2.16b
+	shl		state1.4s, tmp.4s, #7
+	sri		state1.4s, tmp.4s, #25
+
+	/* state1[0,1,2,3] = state1[3,0,1,2] */
+	ext		state1.16b, state1.16b, state1.16b, #12
+	/* state2[0,1,2,3] = state2[2,3,0,1] */
+	ext		state2.16b, state2.16b, state2.16b, #8
+	/* state3[0,1,2,3] = state3[1,2,3,0] */
+	ext		state3.16b, state3.16b, state3.16b, #4
+
+	subs		w4, w4, #2
+	b.ne		.Ldoubleround
+
+	/* output0 = state0 + state0 */
+	add		state0.4s, state0.4s, copy0.4s
+	/* output1 = state1 + state1 */
+	add		state1.4s, state1.4s, copy1.4s
+	/* output2 = state2 + state2 */
+	add		state2.4s, state2.4s, copy2.4s
+	/* output2 = state3 + state3 */
+	add		state3.4s, state3.4s, copy3.4s
+	st1		{ state0.4s - state3.4s }, [x0]
+
+	/* ++copy3.counter */
+	add		copy3_d, copy3_d, one_d
+
+	/* output += 64, --nblocks */
+	add		x0, x0, 64
+	subs		x3, x3, #1
+	b.ne		.Lblock
+
+	/* counter = copy3.counter */
+	str		copy3_d, [x2]
+
+	/* Zero out the potentially sensitive regs, in case nothing uses these again. */
+	eor		state0.16b, state0.16b, state0.16b
+	eor		state1.16b, state1.16b, state1.16b
+	eor		state2.16b, state2.16b, state2.16b
+	eor		state3.16b, state3.16b, state3.16b
+	eor		copy1.16b, copy1.16b, copy1.16b
+	eor		copy2.16b, copy2.16b, copy2.16b
+	ret
+SYM_FUNC_END(__arch_chacha20_blocks_nostack)
+
+        .section        ".rodata", "a", %progbits
+        .align          L1_CACHE_SHIFT
+
+CTES:	.word		1634760805, 857760878, 	2036477234, 1797285236
+ONE:    .xword		1, 0
+ROT8:	.word		0x02010003, 0x06050407, 0x0a09080b, 0x0e0d0c0f
+
+emit_aarch64_feature_1_and
diff --git a/arch/arm64/kernel/vdso/vgetrandom.c b/arch/arm64/kernel/vdso/vgetrandom.c
new file mode 100644
index 000000000000..0833d25f3121
--- /dev/null
+++ b/arch/arm64/kernel/vdso/vgetrandom.c
@@ -0,0 +1,15 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+typeof(__cvdso_getrandom) __kernel_getrandom;
+
+ssize_t __kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len)
+{
+	asm goto (
+	ALTERNATIVE("b %[fallback]", "nop", RM64_HAS_FPSIMD) : : : : fallback);
+	return __cvdso_getrandom(buffer, len, flags, opaque_state, opaque_len);
+
+fallback:
+	if (unlikely(opaque_len == ~0UL && !buffer && !len && !flags))
+		return -ENOSYS;
+	return getrandom_syscall(buffer, len, flags);
+}
diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c
index 938ca539aaa6..7c9711248d9b 100644
--- a/lib/vdso/getrandom.c
+++ b/lib/vdso/getrandom.c
@@ -5,6 +5,7 @@ 
 
 #include <linux/array_size.h>
 #include <linux/minmax.h>
+#include <linux/mm.h>
 #include <vdso/datapage.h>
 #include <vdso/getrandom.h>
 #include <vdso/unaligned.h>
diff --git a/tools/arch/arm64/vdso b/tools/arch/arm64/vdso
new file mode 120000
index 000000000000..233c7a26f6e5
--- /dev/null
+++ b/tools/arch/arm64/vdso
@@ -0,0 +1 @@ 
+../../../arch/arm64/kernel/vdso
\ No newline at end of file
diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 6f7f22ac9da5..4366da278033 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -2,6 +2,8 @@ 
 #ifndef _TOOLS_LINUX_COMPILER_H_
 #define _TOOLS_LINUX_COMPILER_H_
 
+#ifndef __ASSEMBLY__
+
 #include <linux/compiler_types.h>
 
 #ifndef __compiletime_error
@@ -224,4 +226,6 @@  static __always_inline void __write_once_size(volatile void *p, void *res, int s
 	__asm__ ("" : "=r" (var) : "0" (var))
 #endif
 
+#endif /* __ASSEMBLY__ */
+
 #endif /* _TOOLS_LINUX_COMPILER_H */
diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
index e21e78aae24d..29b4ac928e0b 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -1,6 +1,6 @@ 
 # SPDX-License-Identifier: GPL-2.0
 uname_M := $(shell uname -m 2>/dev/null || echo not)
-ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
+ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/ -e s/aarch64.*/arm64/)
 
 TEST_GEN_PROGS := vdso_test_gettimeofday
 TEST_GEN_PROGS += vdso_test_getcpu
@@ -10,7 +10,7 @@  ifeq ($(ARCH),$(filter $(ARCH),x86 x86_64))
 TEST_GEN_PROGS += vdso_standalone_test_x86
 endif
 TEST_GEN_PROGS += vdso_test_correctness
-ifeq ($(uname_M),x86_64)
+ifeq ($(uname_M), $(filter x86_64 aarch64, $(uname_M)))
 TEST_GEN_PROGS += vdso_test_getrandom
 TEST_GEN_PROGS += vdso_test_chacha
 endif
@@ -41,5 +41,6 @@  $(OUTPUT)/vdso_test_getrandom: CFLAGS += -isystem $(top_srcdir)/tools/include \
 $(OUTPUT)/vdso_test_chacha: $(top_srcdir)/tools/arch/$(ARCH)/vdso/vgetrandom-chacha.S
 $(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
                                       -idirafter $(top_srcdir)/arch/$(ARCH)/include \
+                                      -idirafter $(top_srcdir)/arch/$(ARCH)/include/generated \
                                       -idirafter $(top_srcdir)/include \
                                       -D__ASSEMBLY__ -Wa,--noexecstack