To be consistent with other VDSO functions, the function is called
__kernel_getrandom()
__arch_chacha20_blocks_nostack() fonction is implemented basically
with 32 bits operations. It performs 4 QUARTERROUND operations in
parallele. There are enough registers to avoid using the stack:
On input:
r3: output bytes
r4: 32-byte key input
r5: 8-byte counter input/output
r6: number of 64-byte blocks to write to output
During operation:
stack: pointer to counter (r5) and non-volatile registers (r14-131)
r0: counter of blocks (initialised with r6)
r4: Value '4' after key has been read, used for indexing
r5-r12: key
r14-r15: block counter
r16-r31: chacha state
At the end:
r0, r6-r12: Zeroised
r5, r14-r31: Restored
Performance on powerpc 885 (using kernel selftest):
~# ./vdso_test_getrandom bench-single
vdso: 25000000 times in 62.938002291 seconds
libc: 25000000 times in 535.581916866 seconds
syscall: 25000000 times in 531.525042806 seconds
Performance on powerpc 8321 (using kernel selftest):
~# ./vdso_test_getrandom bench-single
vdso: 25000000 times in 16.899318858 seconds
libc: 25000000 times in 131.050596522 seconds
syscall: 25000000 times in 129.794790389 seconds
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
v3:
- Preserve r13, implies saving r5 on stack
- Split PPC64 implementation out.
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/asm-compat.h | 8 +
arch/powerpc/include/asm/vdso/getrandom.h | 54 +++++
arch/powerpc/include/asm/vdso/vsyscall.h | 6 +
arch/powerpc/include/asm/vdso_datapage.h | 2 +
arch/powerpc/kernel/asm-offsets.c | 1 +
arch/powerpc/kernel/vdso/Makefile | 12 +-
arch/powerpc/kernel/vdso/getrandom.S | 50 +++++
arch/powerpc/kernel/vdso/vdso32.lds.S | 1 +
arch/powerpc/kernel/vdso/vgetrandom-chacha.S | 201 +++++++++++++++++++
arch/powerpc/kernel/vdso/vgetrandom.c | 14 ++
tools/arch/powerpc/vdso | 1 +
tools/testing/selftests/vDSO/Makefile | 4 +
13 files changed, 353 insertions(+), 2 deletions(-)
create mode 100644 arch/powerpc/include/asm/vdso/getrandom.h
create mode 100644 arch/powerpc/kernel/vdso/getrandom.S
create mode 100644 arch/powerpc/kernel/vdso/vgetrandom-chacha.S
create mode 100644 arch/powerpc/kernel/vdso/vgetrandom.c
create mode 120000 tools/arch/powerpc/vdso
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d7b09b064a8a..54b270ef18b1 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -311,6 +311,7 @@ config PPC
select SYSCTL_EXCEPTION_TRACE
select THREAD_INFO_IN_TASK
select TRACE_IRQFLAGS_SUPPORT
+ select VDSO_GETRANDOM if PPC32
#
# Please keep this list sorted alphabetically.
#
diff --git a/arch/powerpc/include/asm/asm-compat.h b/arch/powerpc/include/asm/asm-compat.h
index b0b209c1df50..cce8c31b1b33 100644
--- a/arch/powerpc/include/asm/asm-compat.h
+++ b/arch/powerpc/include/asm/asm-compat.h
@@ -59,4 +59,12 @@
#endif
+#ifdef __BIG_ENDIAN__
+#define LWZX_LE stringify_in_c(lwbrx)
+#define STWX_LE stringify_in_c(stwbrx)
+#else
+#define LWZX_LE stringify_in_c(lwzx)
+#define STWX_LE stringify_in_c(stwx)
+#endif
+
#endif /* _ASM_POWERPC_ASM_COMPAT_H */
diff --git a/arch/powerpc/include/asm/vdso/getrandom.h b/arch/powerpc/include/asm/vdso/getrandom.h
new file mode 100644
index 000000000000..501d6bb14e8a
--- /dev/null
+++ b/arch/powerpc/include/asm/vdso/getrandom.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@xxxxxxxxxx>, CS GROUP France
+ */
+#ifndef _ASM_POWERPC_VDSO_GETRANDOM_H
+#define _ASM_POWERPC_VDSO_GETRANDOM_H
+
+#ifndef __ASSEMBLY__
+
+static __always_inline int do_syscall_3(const unsigned long _r0, const unsigned long _r3,
+ const unsigned long _r4, const unsigned long _r5)
+{
+ register long r0 asm("r0") = _r0;
+ register unsigned long r3 asm("r3") = _r3;
+ register unsigned long r4 asm("r4") = _r4;
+ register unsigned long r5 asm("r5") = _r5;
+ register int ret asm ("r3");
+
+ asm volatile(
+ " sc\n"
+ " bns+ 1f\n"
+ " neg %0, %0\n"
+ "1:\n"
+ : "=r" (ret), "+r" (r4), "+r" (r5), "+r" (r0)
+ : "r" (r3)
+ : "memory", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "cr0", "ctr");
+
+ return ret;
+}
+
+/**
+ * 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 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)
+{
+ return do_syscall_3(__NR_getrandom, (unsigned long)buffer,
+ (unsigned long)len, (unsigned long)flags);
+}
+
+static __always_inline struct vdso_rng_data *__arch_get_vdso_rng_data(void)
+{
+ return NULL;
+}
+
+ssize_t __c_kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state,
+ size_t opaque_len, const struct vdso_rng_data *vd);
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* _ASM_POWERPC_VDSO_GETRANDOM_H */
diff --git a/arch/powerpc/include/asm/vdso/vsyscall.h b/arch/powerpc/include/asm/vdso/vsyscall.h
index 48cf23f1e273..92f480d8cc6d 100644
--- a/arch/powerpc/include/asm/vdso/vsyscall.h
+++ b/arch/powerpc/include/asm/vdso/vsyscall.h
@@ -17,6 +17,12 @@ struct vdso_data *__arch_get_k_vdso_data(void)
}
#define __arch_get_k_vdso_data __arch_get_k_vdso_data
+static __always_inline
+struct vdso_rng_data *__arch_get_k_vdso_rng_data(void)
+{
+ return &vdso_data->rng_data;
+}
+
/* The asm-generic header needs to be included after the definitions above */
#include <asm-generic/vdso/vsyscall.h>
diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index a585c8e538ff..e17500c5237e 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -83,6 +83,7 @@ struct vdso_arch_data {
__u32 compat_syscall_map[SYSCALL_MAP_SIZE]; /* Map of compat syscalls */
struct vdso_data data[CS_BASES];
+ struct vdso_rng_data rng_data;
};
#else /* CONFIG_PPC64 */
@@ -95,6 +96,7 @@ struct vdso_arch_data {
__u32 syscall_map[SYSCALL_MAP_SIZE]; /* Map of syscalls */
__u32 compat_syscall_map[0]; /* No compat syscalls on PPC32 */
struct vdso_data data[CS_BASES];
+ struct vdso_rng_data rng_data;
};
#endif /* CONFIG_PPC64 */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 23733282de4d..eedb2e04c785 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -335,6 +335,7 @@ int main(void)
/* datapage offsets for use by vdso */
OFFSET(VDSO_DATA_OFFSET, vdso_arch_data, data);
+ OFFSET(VDSO_RNG_DATA_OFFSET, vdso_arch_data, rng_data);
OFFSET(CFG_TB_TICKS_PER_SEC, vdso_arch_data, tb_ticks_per_sec);
#ifdef CONFIG_PPC64
OFFSET(CFG_ICACHE_BLOCKSZ, vdso_arch_data, icache_block_size);
diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 67fe79d26fae..fa0b9b3b51af 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -8,6 +8,8 @@ include $(srctree)/lib/vdso/Makefile
obj-vdso32 = sigtramp32-32.o gettimeofday-32.o datapage-32.o cacheflush-32.o note-32.o getcpu-32.o
obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o note-64.o getcpu-64.o
+obj-vdso32 += getrandom-32.o vgetrandom-chacha-32.o
+
ifneq ($(c-gettimeofday-y),)
CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
# Go prior to 1.16.x assumes r30 is not clobbered by any VDSO code. That used to be true
@@ -17,6 +19,10 @@ ifneq ($(c-gettimeofday-y),)
CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call cc-option, -ffixed-r30)
endif
+ifneq ($(c-getrandom-y),)
+ CFLAGS_vgetrandom-32.o += -include $(c-getrandom-y)
+endif
+
# Build rules
ifdef CROSS32_COMPILE
@@ -25,7 +31,7 @@ else
VDSOCC := $(CC)
endif
-targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o
+targets := $(obj-vdso32) vdso32.so.dbg vgettimeofday-32.o vgetrandom-32.o
targets += crtsavres-32.o
obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o
@@ -63,7 +69,7 @@ targets += vdso64.lds
CPPFLAGS_vdso64.lds += -P -C
# link rule for the .so file, .lds has to be first
-$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/crtsavres-32.o FORCE
+$(obj)/vdso32.so.dbg: $(obj)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday-32.o $(obj)/vgetrandom-32.o $(obj)/crtsavres-32.o FORCE
$(call if_changed,vdso32ld_and_check)
$(obj)/vdso64.so.dbg: $(obj)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday-64.o FORCE
$(call if_changed,vdso64ld_and_check)
@@ -75,6 +81,8 @@ $(obj)/crtsavres-32.o: %-32.o: $(srctree)/arch/powerpc/lib/crtsavres.S FORCE
$(call if_changed_dep,vdso32as)
$(obj)/vgettimeofday-32.o: %-32.o: %.c FORCE
$(call if_changed_dep,vdso32cc)
+$(obj)/vgetrandom-32.o: %-32.o: %.c FORCE
+ $(call if_changed_dep,vdso32cc)
$(obj-vdso64): %-64.o: %.S FORCE
$(call if_changed_dep,vdso64as)
$(obj)/vgettimeofday-64.o: %-64.o: %.c FORCE
diff --git a/arch/powerpc/kernel/vdso/getrandom.S b/arch/powerpc/kernel/vdso/getrandom.S
new file mode 100644
index 000000000000..21773ef3fc1d
--- /dev/null
+++ b/arch/powerpc/kernel/vdso/getrandom.S
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Userland implementation of getrandom() for processes
+ * for use in the vDSO
+ *
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@xxxxxxxxxx>, CS GROUP France
+ */
+#include <asm/processor.h>
+#include <asm/ppc_asm.h>
+#include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
+#include <asm/asm-offsets.h>
+#include <asm/unistd.h>
+
+/*
+ * The macro sets two stack frames, one for the caller and one for the callee
+ * because there are no requirement for the caller to set a stack frame when
+ * calling VDSO so it may have omitted to set one, especially on PPC64
+ */
+
+.macro cvdso_call funct
+ .cfi_startproc
+ PPC_STLU r1, -PPC_MIN_STKFRM(r1)
+ .cfi_adjust_cfa_offset PPC_MIN_STKFRM
+ mflr r0
+ PPC_STLU r1, -PPC_MIN_STKFRM(r1)
+ .cfi_adjust_cfa_offset PPC_MIN_STKFRM
+ PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
+ .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF
+ get_datapage r8
+ addi r8, r8, VDSO_RNG_DATA_OFFSET
+ bl CFUNC(DOTSYM(\funct))
+ PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1)
+ cmpwi r3, 0
+ mtlr r0
+ addi r1, r1, 2 * PPC_MIN_STKFRM
+ .cfi_restore lr
+ .cfi_def_cfa_offset 0
+ crclr so
+ bgelr+
+ crset so
+ neg r3, r3
+ blr
+ .cfi_endproc
+.endm
+
+ .text
+V_FUNCTION_BEGIN(__kernel_getrandom)
+ cvdso_call __c_kernel_getrandom
+V_FUNCTION_END(__kernel_getrandom)
diff --git a/arch/powerpc/kernel/vdso/vdso32.lds.S b/arch/powerpc/kernel/vdso/vdso32.lds.S
index 8f57107000a2..7b41d5d256e8 100644
--- a/arch/powerpc/kernel/vdso/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso32.lds.S
@@ -130,6 +130,7 @@ VERSION
#if defined(CONFIG_PPC64) || !defined(CONFIG_SMP)
__kernel_getcpu;
#endif
+ __kernel_getrandom;
local: *;
};
diff --git a/arch/powerpc/kernel/vdso/vgetrandom-chacha.S b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
new file mode 100644
index 000000000000..a3475b9e8c10
--- /dev/null
+++ b/arch/powerpc/kernel/vdso/vgetrandom-chacha.S
@@ -0,0 +1,201 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@xxxxxxxxxx>, CS GROUP France
+ */
+
+#include <linux/linkage.h>
+
+#include <asm/ppc_asm.h>
+
+.macro quarterround4 a1 b1 c1 d1 a2 b2 c2 d2 a3 b3 c3 d3 a4 b4 c4 d4
+ add \a1, \a1, \b1
+ add \a2, \a2, \b2
+ add \a3, \a3, \b3
+ add \a4, \a4, \b4
+ xor \d1, \d1, \a1
+ xor \d2, \d2, \a2
+ xor \d3, \d3, \a3
+ xor \d4, \d4, \a4
+ rotlwi \d1, \d1, 16
+ rotlwi \d2, \d2, 16
+ rotlwi \d3, \d3, 16
+ rotlwi \d4, \d4, 16
+ add \c1, \c1, \d1
+ add \c2, \c2, \d2
+ add \c3, \c3, \d3
+ add \c4, \c4, \d4
+ xor \b1, \b1, \c1
+ xor \b2, \b2, \c2
+ xor \b3, \b3, \c3
+ xor \b4, \b4, \c4
+ rotlwi \b1, \b1, 12
+ rotlwi \b2, \b2, 12
+ rotlwi \b3, \b3, 12
+ rotlwi \b4, \b4, 12
+ add \a1, \a1, \b1
+ add \a2, \a2, \b2
+ add \a3, \a3, \b3
+ add \a4, \a4, \b4
+ xor \d1, \d1, \a1
+ xor \d2, \d2, \a2
+ xor \d3, \d3, \a3
+ xor \d4, \d4, \a4
+ rotlwi \d1, \d1, 8
+ rotlwi \d2, \d2, 8
+ rotlwi \d3, \d3, 8
+ rotlwi \d4, \d4, 8
+ add \c1, \c1, \d1
+ add \c2, \c2, \d2
+ add \c3, \c3, \d3
+ add \c4, \c4, \d4
+ xor \b1, \b1, \c1
+ xor \b2, \b2, \c2
+ xor \b3, \b3, \c3
+ xor \b4, \b4, \c4
+ rotlwi \b1, \b1, 7
+ rotlwi \b2, \b2, 7
+ rotlwi \b3, \b3, 7
+ rotlwi \b4, \b4, 7
+.endm
+
+#define QUARTERROUND4(a1,b1,c1,d1,a2,b2,c2,d2,a3,b3,c3,d3,a4,b4,c4,d4) \
+ quarterround4 16+a1 16+b1 16+c1 16+d1 16+a2 16+b2 16+c2 16+d2 \
+ 16+a3 16+b3 16+c3 16+d3 16+a4 16+b4 16+c4 16+d4
+
+/*
+ * Very basic 32 bits implementation of ChaCha20. Produces a given positive number
+ * of blocks of output with a nonce of 0, taking an input key and 8-byte
+ * counter. Importantly does not spill to the stack. Its arguments are:
+ *
+ * r3: output bytes
+ * r4: 32-byte key input
+ * r5: 8-byte counter input/output (saved on stack)
+ * r6: number of 64-byte blocks to write to output
+ *
+ * r0: counter of blocks (initialised with r6)
+ * r4: Value '4' after key has been read.
+ * r5-r12: key
+ * r14-r15: counter
+ * r16-r31: state
+ */
+SYM_FUNC_START(__arch_chacha20_blocks_nostack)
+ stwu r1, -96(r1)
+ stw r5, 20(r1)
+ stmw r14, 24(r1)
+ li r31, 4
+ LWZX_LE r14, 0, r5
+ LWZX_LE r15, r31, r5
+ mr r0, r6
+
+ lwz r5, 0(r4)
+ lwz r6, 4(r4)
+ lwz r7, 8(r4)
+ lwz r8, 12(r4)
+ lwz r9, 16(r4)
+ lwz r10, 20(r4)
+ lwz r11, 24(r4)
+ lwz r12, 28(r4)
+
+ li r4, 4
+.Lblock:
+ li r31, 10
+
+ lis r16, 0x6170
+ lis r17, 0x3320
+ lis r18, 0x7962
+ lis r19, 0x6b20
+ addi r16, r16, 0x7865
+ addi r17, r17, 0x646e
+ addi r18, r18, 0x2d32
+ addi r19, r19, 0x6574
+
+ mtctr r31
+
+ mr r20, r5
+ mr r21, r6
+ mr r22, r7
+ mr r23, r8
+ mr r24, r9
+ mr r25, r10
+ mr r26, r11
+ mr r27, r12
+
+ mr r28, r14
+ mr r29, r15
+ li r30, 0
+ li r31, 0
+
+.Lpermute:
+ QUARTERROUND4( 0, 4, 8,12, 1, 5, 9,13, 2, 6,10,14, 3, 7,11,15)
+ QUARTERROUND4( 0, 5,10,15, 1, 6,11,12, 2, 7, 8,13, 3, 4, 9,14)
+
+ bdnz .Lpermute
+
+ addis r16, r16, 0x6170
+ addis r17, r17, 0x3320
+ addis r18, r18, 0x7962
+ addis r19, r19, 0x6b20
+ addi r16, r16, 0x7865
+ addi r17, r17, 0x646e
+ addi r18, r18, 0x2d32
+ addi r19, r19, 0x6574
+
+ add r20, r20, r5
+ add r21, r21, r6
+ add r22, r22, r7
+ add r23, r23, r8
+ add r24, r24, r9
+ add r25, r25, r10
+ add r26, r26, r11
+ add r27, r27, r12
+
+ add r28, r28, r14
+ add r29, r29, r15
+
+ STWX_LE r16, 0, r3
+ STWX_LE r17, r4, r3
+ addi r3, r3, 8
+ STWX_LE r18, 0, r3
+ STWX_LE r19, r4, r3
+ addi r3, r3, 8
+ STWX_LE r20, 0, r3
+ STWX_LE r21, r4, r3
+ addi r3, r3, 8
+ STWX_LE r22, 0, r3
+ STWX_LE r23, r4, r3
+ addi r3, r3, 8
+ STWX_LE r24, 0, r3
+ STWX_LE r25, r4, r3
+ addi r3, r3, 8
+ STWX_LE r26, 0, r3
+ STWX_LE r27, r4, r3
+ addi r3, r3, 8
+ STWX_LE r28, 0, r3
+ STWX_LE r29, r4, r3
+ addi r3, r3, 8
+ STWX_LE r30, 0, r3
+ STWX_LE r31, r4, r3
+ addi r3, r3, 8
+
+ addic r14, r14, 1
+ addze r15, r15
+
+ subic. r0, r0, 1 /* subi. can't use r0 as source */
+ bne .Lblock
+
+ lwz r5, 20(r1)
+ STWX_LE r14, 0, r5
+ STWX_LE r15, r4, r5
+
+ li r6, 0
+ li r7, 0
+ li r8, 0
+ li r9, 0
+ li r10, 0
+ li r11, 0
+ li r12, 0
+
+ lmw r14, 24(r1)
+ addi r1, r1, 96
+ blr
+SYM_FUNC_END(__arch_chacha20_blocks_nostack)
diff --git a/arch/powerpc/kernel/vdso/vgetrandom.c b/arch/powerpc/kernel/vdso/vgetrandom.c
new file mode 100644
index 000000000000..5f855d45fb7b
--- /dev/null
+++ b/arch/powerpc/kernel/vdso/vgetrandom.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Powerpc userspace implementation of getrandom()
+ *
+ * Copyright (C) 2024 Christophe Leroy <christophe.leroy@xxxxxxxxxx>, CS GROUP France
+ */
+#include <linux/time.h>
+#include <linux/types.h>
+
+ssize_t __c_kernel_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state,
+ size_t opaque_len, const struct vdso_rng_data *vd)
+{
+ return __cvdso_getrandom_data(vd, buffer, len, flags, opaque_state, opaque_len);
+}
diff --git a/tools/arch/powerpc/vdso b/tools/arch/powerpc/vdso
new file mode 120000
index 000000000000..d31004bf8f55
--- /dev/null
+++ b/tools/arch/powerpc/vdso
@@ -0,0 +1 @@
+../../../arch/powerpc/kernel/vdso/
\ No newline at end of file
diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
index e21e78aae24d..e57dcefa1988 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -14,6 +14,10 @@ ifeq ($(uname_M),x86_64)
TEST_GEN_PROGS += vdso_test_getrandom
TEST_GEN_PROGS += vdso_test_chacha
endif
+ifeq ($(ARCH),powerpc)
+TEST_GEN_PROGS += vdso_test_getrandom
+TEST_GEN_PROGS += vdso_test_chacha
+endif
CFLAGS := -std=gnu99
--
2.44.0
