Unverified Commit ee0d0305 authored by Xi Ruoyao's avatar Xi Ruoyao Committed by Palmer Dabbelt
Browse files

RISC-V: vDSO: Wire up getrandom() vDSO implementation 

Hook up the generic vDSO implementation to the generic vDSO getrandom
implementation by providing the required __arch_chacha20_blocks_nostack
and getrandom_syscall implementations. Also wire up the selftests.

The benchmark result:

	vdso: 25000000 times in 2.466341333 seconds
	libc: 25000000 times in 41.447720005 seconds
	syscall: 25000000 times in 41.043926672 seconds

	vdso: 25000000 x 256 times in 162.286219353 seconds
	libc: 25000000 x 256 times in 2953.855018685 seconds
	syscall: 25000000 x 256 times in 2796.268546000 seconds

[ alex: - Fix dynamic relocation
        - Squash Nathan's fix https://lore.kernel.org/all/20250423-riscv-fix-compat_vdso-lld-v2-1-b7bbbc244501@kernel.org/


	- Add comment from Loongarch ]

Signed-off-by: default avatarXi Ruoyao <xry111@xry111.site>
Link: https://lore.kernel.org/r/20250411024600.16045-1-xry111@xry111.site


Tested-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@dabbelt.com>
parent a869b8c2

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -219,6 +219,7 @@ config RISCV 
	select THREAD_INFO_IN_TASK

	select TRACE_IRQFLAGS_SUPPORT

	select UACCESS_MEMCPY if !MMU

	select VDSO_GETRANDOM if HAVE_GENERIC_VDSO

	select USER_STACKTRACE_SUPPORT

	select ZONE_DMA32 if 64BIT

arch/riscv/include/asm/vdso/getrandom.h

0 → 100644
+30 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (C) 2025 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved.

 */

#ifndef __ASM_VDSO_GETRANDOM_H

#define __ASM_VDSO_GETRANDOM_H



#ifndef __ASSEMBLY__



#include <asm/unistd.h>



static __always_inline ssize_t getrandom_syscall(void *_buffer, size_t _len, unsigned int _flags)

{

	register long ret asm("a0");

	register long nr asm("a7") = __NR_getrandom;

	register void *buffer asm("a0") = _buffer;

	register size_t len asm("a1") = _len;

	register unsigned int flags asm("a2") = _flags;



	asm volatile ("ecall\n"

		      : "+r" (ret)

		      : "r" (nr), "r" (buffer), "r" (len), "r" (flags)

		      : "memory");



	return ret;

}



#endif /* !__ASSEMBLY__ */



#endif /* __ASM_VDSO_GETRANDOM_H */

arch/riscv/kernel/vdso/Makefile

+13 −0
Original line number Diff line number Diff line
@@ -13,9 +13,17 @@ vdso-syms += flush_icache 
vdso-syms += hwprobe

vdso-syms += sys_hwprobe



ifdef CONFIG_VDSO_GETRANDOM

vdso-syms += getrandom

endif



# Files to link into the vdso

obj-vdso = $(patsubst %, %.o, $(vdso-syms)) note.o



ifdef CONFIG_VDSO_GETRANDOM

obj-vdso += vgetrandom-chacha.o

endif



ccflags-y := -fno-stack-protector

ccflags-y += -DDISABLE_BRANCH_PROFILING

ccflags-y += -fno-builtin
@@ -24,6 +32,10 @@ ifneq ($(c-gettimeofday-y),) 
  CFLAGS_vgettimeofday.o += -fPIC -include $(c-gettimeofday-y)

endif



ifneq ($(c-getrandom-y),)

  CFLAGS_getrandom.o += -fPIC -include $(c-getrandom-y)

endif



CFLAGS_hwprobe.o += -fPIC



# Build rules
@@ -38,6 +50,7 @@ endif 


# Disable -pg to prevent insert call site

CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)

CFLAGS_REMOVE_getrandom.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)

CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)



# Force dependency

arch/riscv/kernel/vdso/getrandom.c

0 → 100644
+10 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright (C) 2025 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved.

 */

#include <linux/types.h>



ssize_t __vdso_getrandom(void *buffer, size_t len, unsigned int flags, void *opaque_state, size_t opaque_len)

{

	return __cvdso_getrandom(buffer, len, flags, opaque_state, opaque_len);

}

arch/riscv/kernel/vdso/vdso.lds.S

+3 −0
Original line number Diff line number Diff line
@@ -79,6 +79,9 @@ VERSION 
		__vdso_flush_icache;

#ifndef COMPAT_VDSO

		__vdso_riscv_hwprobe;

#endif

#if defined(CONFIG_VDSO_GETRANDOM) && !defined(COMPAT_VDSO)

		__vdso_getrandom;

#endif

	local: *;

	};