| Message ID | 20240816110717.10249-2-xry111@xry111.site (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | [v3,1/3] LoongArch: vDSO: Wire up getrandom() vDSO implementation | expand |
Hi, Ruoyao, On Fri, Aug 16, 2024 at 7:07 PM Xi Ruoyao <xry111@xry111.site> wrote: > > Hook up the generic vDSO implementation to the LoongArch vDSO data page: > embed struct vdso_rng_data into struct loongarch_vdso_data, and use > assembler hack to resolve the symbol name "_vdso_rng_data" (which is > expected by the generic vDSO implementation) to the rng_data field in > loongarch_vdso_data. > > The compiler (GCC 14.2) calls memset() for initializing a "large" struct > in a cold path of the generic vDSO getrandom() code. There seems no way > to prevent it from calling memset(), and it's a cold path so the > performance does not matter, so just provide a naive memset() > implementation for vDSO. Why x86 doesn't need to provide a naive memset()? > > Signed-off-by: Xi Ruoyao <xry111@xry111.site> > --- > arch/loongarch/Kconfig | 1 + > arch/loongarch/include/asm/vdso/getrandom.h | 47 ++++ > arch/loongarch/include/asm/vdso/vdso.h | 8 + > arch/loongarch/kernel/asm-offsets.c | 10 + > arch/loongarch/kernel/vdso.c | 6 + > arch/loongarch/vdso/Makefile | 2 + > arch/loongarch/vdso/memset.S | 24 ++ > arch/loongarch/vdso/vdso.lds.S | 1 + > arch/loongarch/vdso/vgetrandom-chacha.S | 239 ++++++++++++++++++++ > arch/loongarch/vdso/vgetrandom.c | 19 ++ > 10 files changed, 357 insertions(+) > create mode 100644 arch/loongarch/include/asm/vdso/getrandom.h > create mode 100644 arch/loongarch/vdso/memset.S > create mode 100644 arch/loongarch/vdso/vgetrandom-chacha.S > create mode 100644 arch/loongarch/vdso/vgetrandom.c > > diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig > index 70f169210b52..14821c2aba5b 100644 > --- a/arch/loongarch/Kconfig > +++ b/arch/loongarch/Kconfig > @@ -190,6 +190,7 @@ config LOONGARCH > select TRACE_IRQFLAGS_SUPPORT > select USE_PERCPU_NUMA_NODE_ID > select USER_STACKTRACE_SUPPORT > + select VDSO_GETRANDOM > select ZONE_DMA32 > > config 32BIT > diff --git a/arch/loongarch/include/asm/vdso/getrandom.h b/arch/loongarch/include/asm/vdso/getrandom.h > new file mode 100644 > index 000000000000..a369588a4ebf > --- /dev/null > +++ b/arch/loongarch/include/asm/vdso/getrandom.h > @@ -0,0 +1,47 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2024 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved. > + */ > +#ifndef __ASM_VDSO_GETRANDOM_H > +#define __ASM_VDSO_GETRANDOM_H > + > +#ifndef __ASSEMBLY__ > + > +#include <asm/unistd.h> > +#include <asm/vdso/vdso.h> > + > +static __always_inline ssize_t getrandom_syscall(void *_buffer, > + size_t _len, > + unsigned int _flags) > +{ > + register long ret asm("a0"); > + register long int 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( > + " syscall 0\n" > + : "+r" (ret) > + : "r" (nr), "r" (buffer), "r" (len), "r" (flags) > + : "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7", "$t8", > + "memory"); > + > + return ret; > +} > + > +static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data( > + void) Don't need a line break. > +{ > + return (const struct vdso_rng_data *)( > + get_vdso_data() + > + VVAR_LOONGARCH_PAGES_START * PAGE_SIZE + > + offsetof(struct loongarch_vdso_data, rng_data)); > +} > + > +extern void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, > + u32 *counter, size_t nblocks); > + > +#endif /* !__ASSEMBLY__ */ > + > +#endif /* __ASM_VDSO_GETRANDOM_H */ > diff --git a/arch/loongarch/include/asm/vdso/vdso.h b/arch/loongarch/include/asm/vdso/vdso.h > index 5a12309d9fb5..a2e24c3007e2 100644 > --- a/arch/loongarch/include/asm/vdso/vdso.h > +++ b/arch/loongarch/include/asm/vdso/vdso.h > @@ -4,6 +4,9 @@ > * Copyright (C) 2020-2022 Loongson Technology Corporation Limited > */ > > +#ifndef _ASM_VDSO_VDSO_H > +#define _ASM_VDSO_VDSO_H > + > #ifndef __ASSEMBLY__ > > #include <asm/asm.h> > @@ -16,6 +19,9 @@ struct vdso_pcpu_data { > > struct loongarch_vdso_data { > struct vdso_pcpu_data pdata[NR_CPUS]; > +#ifdef CONFIG_VDSO_GETRANDOM You select VDSO_GETRANDOM unconditionally, so #ifdef is useless. > + struct vdso_rng_data rng_data; > +#endif > }; > > /* > @@ -63,3 +69,5 @@ static inline unsigned long get_vdso_data(void) > } > > #endif /* __ASSEMBLY__ */ > + > +#endif > diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c > index bee9f7a3108f..86f6d8a6dc23 100644 > --- a/arch/loongarch/kernel/asm-offsets.c > +++ b/arch/loongarch/kernel/asm-offsets.c > @@ -14,6 +14,7 @@ > #include <asm/ptrace.h> > #include <asm/processor.h> > #include <asm/ftrace.h> > +#include <asm/vdso/vdso.h> > > static void __used output_ptreg_defines(void) > { > @@ -321,3 +322,12 @@ static void __used output_kvm_defines(void) > OFFSET(KVM_GPGD, kvm, arch.pgd); > BLANK(); > } > + > +#ifdef CONFIG_VDSO_GETRANDOM The same. > +static void __used output_vdso_rng_defines(void) > +{ > + COMMENT("LoongArch VDSO getrandom offsets."); > + OFFSET(VDSO_RNG_DATA, loongarch_vdso_data, rng_data); > + BLANK(); > +} > +#endif > diff --git a/arch/loongarch/kernel/vdso.c b/arch/loongarch/kernel/vdso.c > index 90dfccb41c14..15b65d8e2fdc 100644 > --- a/arch/loongarch/kernel/vdso.c > +++ b/arch/loongarch/kernel/vdso.c > @@ -22,6 +22,7 @@ > #include <vdso/helpers.h> > #include <vdso/vsyscall.h> > #include <vdso/datapage.h> > +#include <generated/asm-offsets.h> > #include <generated/vdso-offsets.h> > > extern char vdso_start[], vdso_end[]; > @@ -34,6 +35,11 @@ static union { > struct loongarch_vdso_data vdata; > } loongarch_vdso_data __page_aligned_data; > > +#ifdef CONFIG_VDSO_GETRANDOM The same. > +asm(".globl _vdso_rng_data\n" > + ".set _vdso_rng_data, loongarch_vdso_data + " __stringify(VDSO_RNG_DATA)); > +#endif > + > static struct page *vdso_pages[] = { NULL }; > struct vdso_data *vdso_data = generic_vdso_data.data; > struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata; > diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile > index 2ddf0480e710..c8c5d9a7c80c 100644 > --- a/arch/loongarch/vdso/Makefile > +++ b/arch/loongarch/vdso/Makefile > @@ -6,6 +6,8 @@ include $(srctree)/lib/vdso/Makefile > > obj-vdso-y := elf.o vgetcpu.o vgettimeofday.o sigreturn.o > > +obj-vdso-$(CONFIG_VDSO_GETRANDOM) += vgetrandom.o vgetrandom-chacha.o memset.o > + > # Common compiler flags between ABIs. > ccflags-vdso := \ > $(filter -I%,$(KBUILD_CFLAGS)) \ > diff --git a/arch/loongarch/vdso/memset.S b/arch/loongarch/vdso/memset.S > new file mode 100644 > index 000000000000..ec1531683936 > --- /dev/null > +++ b/arch/loongarch/vdso/memset.S > @@ -0,0 +1,24 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * A copy of __memset_generic from arch/loongarch/lib/memset.S for vDSO. > + * > + * Copyright (C) 2020-2024 Loongson Technology Corporation Limited > + */ > + > +#include <asm/regdef.h> > +#include <linux/linkage.h> > + > +SYM_FUNC_START(memset) > + move a3, a0 > + beqz a2, 2f > + > +1: st.b a1, a0, 0 > + addi.d a0, a0, 1 > + addi.d a2, a2, -1 > + bgt a2, zero, 1b > + > +2: move a0, a3 > + jr ra > +SYM_FUNC_END(memset) > + > +.hidden memset > diff --git a/arch/loongarch/vdso/vdso.lds.S b/arch/loongarch/vdso/vdso.lds.S > index 56ad855896de..2c965a597d9e 100644 > --- a/arch/loongarch/vdso/vdso.lds.S > +++ b/arch/loongarch/vdso/vdso.lds.S > @@ -63,6 +63,7 @@ VERSION > __vdso_clock_gettime; > __vdso_gettimeofday; > __vdso_rt_sigreturn; > + __vdso_getrandom; In my opinion, __vdso_rt_sigreturn is different from others, so I prefer to keep it at last. Huacai > local: *; > }; > } > diff --git a/arch/loongarch/vdso/vgetrandom-chacha.S b/arch/loongarch/vdso/vgetrandom-chacha.S > new file mode 100644 > index 000000000000..2e42198f2faf > --- /dev/null > +++ b/arch/loongarch/vdso/vgetrandom-chacha.S > @@ -0,0 +1,239 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2024 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved. > + */ > + > +#include <asm/asm.h> > +#include <asm/regdef.h> > +#include <linux/linkage.h> > + > +.text > + > +/* Salsa20 quarter-round */ > +.macro QR a b c d > + add.w \a, \a, \b > + xor \d, \d, \a > + rotri.w \d, \d, 16 > + > + add.w \c, \c, \d > + xor \b, \b, \c > + rotri.w \b, \b, 20 > + > + add.w \a, \a, \b > + xor \d, \d, \a > + rotri.w \d, \d, 24 > + > + add.w \c, \c, \d > + xor \b, \b, \c > + rotri.w \b, \b, 25 > +.endm > + > +/* > + * Very basic LoongArch 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: > + * > + * a0: output bytes > + * a1: 32-byte key input > + * a2: 8-byte counter input/output > + * a3: number of 64-byte blocks to write to output > + */ > +SYM_FUNC_START(__arch_chacha20_blocks_nostack) > + > +/* We don't need a frame pointer */ > +#define s9 fp > + > +#define output a0 > +#define key a1 > +#define counter a2 > +#define nblocks a3 > +#define i a4 > +#define state0 s0 > +#define state1 s1 > +#define state2 s2 > +#define state3 s3 > +#define state4 s4 > +#define state5 s5 > +#define state6 s6 > +#define state7 s7 > +#define state8 s8 > +#define state9 s9 > +#define state10 a5 > +#define state11 a6 > +#define state12 a7 > +#define state13 t0 > +#define state14 t1 > +#define state15 t2 > +#define cnt_lo t3 > +#define cnt_hi t4 > +#define copy0 t5 > +#define copy1 t6 > +#define copy2 t7 > + > +/* Reuse i as copy3 */ > +#define copy3 i > + > + /* > + * The ABI requires s0-s9 saved, and sp aligned to 16-byte. > + * This does not violate the stack-less requirement: no sensitive data > + * is spilled onto the stack. > + */ > + PTR_ADDI sp, sp, (-SZREG * 10) & STACK_ALIGN > + REG_S s0, sp, 0 > + REG_S s1, sp, SZREG > + REG_S s2, sp, SZREG * 2 > + REG_S s3, sp, SZREG * 3 > + REG_S s4, sp, SZREG * 4 > + REG_S s5, sp, SZREG * 5 > + REG_S s6, sp, SZREG * 6 > + REG_S s7, sp, SZREG * 7 > + REG_S s8, sp, SZREG * 8 > + REG_S s9, sp, SZREG * 9 > + > + li.w copy0, 0x61707865 > + li.w copy1, 0x3320646e > + li.w copy2, 0x79622d32 > + > + ld.w cnt_lo, counter, 0 > + ld.w cnt_hi, counter, 4 > + > +.Lblock: > + /* state[0,1,2,3] = "expand 32-byte k" */ > + move state0, copy0 > + move state1, copy1 > + move state2, copy2 > + li.w state3, 0x6b206574 > + > + /* state[4,5,..,11] = key */ > + ld.w state4, key, 0 > + ld.w state5, key, 4 > + ld.w state6, key, 8 > + ld.w state7, key, 12 > + ld.w state8, key, 16 > + ld.w state9, key, 20 > + ld.w state10, key, 24 > + ld.w state11, key, 28 > + > + /* state[12,13] = counter */ > + move state12, cnt_lo > + move state13, cnt_hi > + > + /* state[14,15] = 0 */ > + move state14, zero > + move state15, zero > + > + li.w i, 10 > +.Lpermute: > + /* odd round */ > + QR state0, state4, state8, state12 > + QR state1, state5, state9, state13 > + QR state2, state6, state10, state14 > + QR state3, state7, state11, state15 > + > + /* even round */ > + QR state0, state5, state10, state15 > + QR state1, state6, state11, state12 > + QR state2, state7, state8, state13 > + QR state3, state4, state9, state14 > + > + addi.w i, i, -1 > + bnez i, .Lpermute > + > + /* copy[3] = "expa" */ > + li.w copy3, 0x6b206574 > + > + /* output[0,1,2,3] = copy[0,1,2,3] + state[0,1,2,3] */ > + add.w state0, state0, copy0 > + add.w state1, state1, copy1 > + add.w state2, state2, copy2 > + add.w state3, state3, copy3 > + st.w state0, output, 0 > + st.w state1, output, 4 > + st.w state2, output, 8 > + st.w state3, output, 12 > + > + /* from now on state[0,1,2,3] are scratch registers */ > + > + /* state[0,1,2,3] = lo32(key) */ > + ld.w state0, key, 0 > + ld.w state1, key, 4 > + ld.w state2, key, 8 > + ld.w state3, key, 12 > + > + /* output[4,5,6,7] = state[0,1,2,3] + state[4,5,6,7] */ > + add.w state4, state4, state0 > + add.w state5, state5, state1 > + add.w state6, state6, state2 > + add.w state7, state7, state3 > + st.w state4, output, 16 > + st.w state5, output, 20 > + st.w state6, output, 24 > + st.w state7, output, 28 > + > + /* state[0,1,2,3] = hi32(key) */ > + ld.w state0, key, 16 > + ld.w state1, key, 20 > + ld.w state2, key, 24 > + ld.w state3, key, 28 > + > + /* output[8,9,10,11] = state[0,1,2,3] + state[8,9,10,11] */ > + add.w state8, state8, state0 > + add.w state9, state9, state1 > + add.w state10, state10, state2 > + add.w state11, state11, state3 > + st.w state8, output, 32 > + st.w state9, output, 36 > + st.w state10, output, 40 > + st.w state11, output, 44 > + > + /* output[12,13,14,15] = state[12,13,14,15] + [cnt_lo, cnt_hi, 0, 0] */ > + add.w state12, state12, cnt_lo > + add.w state13, state13, cnt_hi > + st.w state12, output, 48 > + st.w state13, output, 52 > + st.w state14, output, 56 > + st.w state15, output, 60 > + > + /* ++counter */ > + addi.w cnt_lo, cnt_lo, 1 > + sltui state0, cnt_lo, 1 > + add.w cnt_hi, cnt_hi, state0 > + > + /* output += 64 */ > + PTR_ADDI output, output, 64 > + /* --nblocks */ > + PTR_ADDI nblocks, nblocks, -1 > + bnez nblocks, .Lblock > + > + /* counter = [cnt_lo, cnt_hi] */ > + st.w cnt_lo, counter, 0 > + st.w cnt_hi, counter, 4 > + > + /* > + * Zero out the potentially sensitive regs, in case nothing uses these > + * again. As at now copy[0,1,2,3] just contains "expand 32-byte k" and > + * state[0,...,9] are s0-s9 those we'll restore in the epilogue, so we > + * only need to zero state[11,...,15]. > + */ > + move state10, zero > + move state11, zero > + move state12, zero > + move state13, zero > + move state14, zero > + move state15, zero > + > + REG_L s0, sp, 0 > + REG_L s1, sp, SZREG > + REG_L s2, sp, SZREG * 2 > + REG_L s3, sp, SZREG * 3 > + REG_L s4, sp, SZREG * 4 > + REG_L s5, sp, SZREG * 5 > + REG_L s6, sp, SZREG * 6 > + REG_L s7, sp, SZREG * 7 > + REG_L s8, sp, SZREG * 8 > + REG_L s9, sp, SZREG * 9 > + PTR_ADDI sp, sp, -((-SZREG * 10) & STACK_ALIGN) > + > + jr ra > +SYM_FUNC_END(__arch_chacha20_blocks_nostack) > diff --git a/arch/loongarch/vdso/vgetrandom.c b/arch/loongarch/vdso/vgetrandom.c > new file mode 100644 > index 000000000000..0b3b30ecd68a > --- /dev/null > +++ b/arch/loongarch/vdso/vgetrandom.c > @@ -0,0 +1,19 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2024 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved. > + */ > +#include <linux/types.h> > + > +#include "../../../../lib/vdso/getrandom.c" > + > +typeof(__cvdso_getrandom) __vdso_getrandom; > + > +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); > +} > + > +typeof(__cvdso_getrandom) getrandom > + __attribute__((weak, alias("__vdso_getrandom"))); > -- > 2.46.0 >
> > The compiler (GCC 14.2) calls memset() for initializing a "large" struct > > in a cold path of the generic vDSO getrandom() code. There seems no way > > to prevent it from calling memset(), and it's a cold path so the > > performance does not matter, so just provide a naive memset() > > implementation for vDSO. > Why x86 doesn't need to provide a naive memset()? It looks like others are running into this when porting to ppc and arm64, so I'll probably refactor the code to avoid needing it in the first place. I'll chime in here when that's done. Jason
On Mon, 2024-08-19 at 13:03 +0000, Jason A. Donenfeld wrote: > > > The compiler (GCC 14.2) calls memset() for initializing a "large" struct > > > in a cold path of the generic vDSO getrandom() code. There seems no way > > > to prevent it from calling memset(), and it's a cold path so the > > > performance does not matter, so just provide a naive memset() > > > implementation for vDSO. > > Why x86 doesn't need to provide a naive memset()? I'm not sure. Maybe it's because x86_64 has SSE2 enabled so by default the maximum buffer length to inline memset is larger. > It looks like others are running into this when porting to ppc and > arm64, so I'll probably refactor the code to avoid needing it in the > first place. I'll chime in here when that's done. Yes, I've seen the PPC guys hacking the code to avoid memset. BTW I've also seen "vDSO getrandom isn't supported on 32-bit platforms" in the PPC discussion. Is there any plan to support it in the future? If not I'll only select VDSO_GETRANDOM if CONFIG_64BIT, and then the assembly code can be slightly simplified.
On 2024-08-19 23:36, Xi Ruoyao wrote: > On Mon, 2024-08-19 at 13:03 +0000, Jason A. Donenfeld wrote: >>>> The compiler (GCC 14.2) calls memset() for initializing a "large" struct >>>> in a cold path of the generic vDSO getrandom() code. There seems no way >>>> to prevent it from calling memset(), and it's a cold path so the >>>> performance does not matter, so just provide a naive memset() >>>> implementation for vDSO. >>> Why x86 doesn't need to provide a naive memset()? > I'm not sure. Maybe it's because x86_64 has SSE2 enabled so by default > the maximum buffer length to inline memset is larger. > I suspect the loongarch gcc has issue with -fno-builtin(-memset).
On Tue, 2024-08-20 at 08:50 +0800, Jinyang He wrote: > On 2024-08-19 23:36, Xi Ruoyao wrote: > > > On Mon, 2024-08-19 at 13:03 +0000, Jason A. Donenfeld wrote: > > > > > The compiler (GCC 14.2) calls memset() for initializing a "large" struct > > > > > in a cold path of the generic vDSO getrandom() code. There seems no way > > > > > to prevent it from calling memset(), and it's a cold path so the > > > > > performance does not matter, so just provide a naive memset() > > > > > implementation for vDSO. > > > > Why x86 doesn't need to provide a naive memset()? > > I'm not sure. Maybe it's because x86_64 has SSE2 enabled so by default > > the maximum buffer length to inline memset is larger. > > > I suspect the loongarch gcc has issue with -fno-builtin(-memset). No, -fno-builtin-memset just means don't convert memset to __builtin_memset, it does not mean "don't emit memset call," nor anything more than that. Even -ffreestanding is not guaranteed to turn off memset call generation because per the standard memset should be available even in a freestanding implementation. x86 has a -mmemset-strategy= option but it's really x86 specific. As Jason pointed out, PowerPC and ARM64 have also hit the same issue.
On 2024-08-20 09:09, Xi Ruoyao wrote: > On Tue, 2024-08-20 at 08:50 +0800, Jinyang He wrote: >> On 2024-08-19 23:36, Xi Ruoyao wrote: >> >>> On Mon, 2024-08-19 at 13:03 +0000, Jason A. Donenfeld wrote: >>>>>> The compiler (GCC 14.2) calls memset() for initializing a "large" struct >>>>>> in a cold path of the generic vDSO getrandom() code. There seems no way >>>>>> to prevent it from calling memset(), and it's a cold path so the >>>>>> performance does not matter, so just provide a naive memset() >>>>>> implementation for vDSO. >>>>> Why x86 doesn't need to provide a naive memset()? >>> I'm not sure. Maybe it's because x86_64 has SSE2 enabled so by default >>> the maximum buffer length to inline memset is larger. >>> >> I suspect the loongarch gcc has issue with -fno-builtin(-memset). > No, -fno-builtin-memset just means don't convert memset to > __builtin_memset, it does not mean "don't emit memset call," nor > anything more than that. > > Even -ffreestanding is not guaranteed to turn off memset call generation > because per the standard memset should be available even in a > freestanding implementation. > > x86 has a -mmemset-strategy= option but it's really x86 specific. As > Jason pointed out, PowerPC and ARM64 have also hit the same issue. > I see. Thanks! The gcc produced __builtin_memset in expand pass. X86 increase the maximum buffer length to inline memset by `-mmemset-strategy=`, while other archs like LoongArch cannot do this.
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 70f169210b52..14821c2aba5b 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -190,6 +190,7 @@ config LOONGARCH select TRACE_IRQFLAGS_SUPPORT select USE_PERCPU_NUMA_NODE_ID select USER_STACKTRACE_SUPPORT + select VDSO_GETRANDOM select ZONE_DMA32 config 32BIT diff --git a/arch/loongarch/include/asm/vdso/getrandom.h b/arch/loongarch/include/asm/vdso/getrandom.h new file mode 100644 index 000000000000..a369588a4ebf --- /dev/null +++ b/arch/loongarch/include/asm/vdso/getrandom.h @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved. + */ +#ifndef __ASM_VDSO_GETRANDOM_H +#define __ASM_VDSO_GETRANDOM_H + +#ifndef __ASSEMBLY__ + +#include <asm/unistd.h> +#include <asm/vdso/vdso.h> + +static __always_inline ssize_t getrandom_syscall(void *_buffer, + size_t _len, + unsigned int _flags) +{ + register long ret asm("a0"); + register long int 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( + " syscall 0\n" + : "+r" (ret) + : "r" (nr), "r" (buffer), "r" (len), "r" (flags) + : "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7", "$t8", + "memory"); + + return ret; +} + +static __always_inline const struct vdso_rng_data *__arch_get_vdso_rng_data( + void) +{ + return (const struct vdso_rng_data *)( + get_vdso_data() + + VVAR_LOONGARCH_PAGES_START * PAGE_SIZE + + offsetof(struct loongarch_vdso_data, rng_data)); +} + +extern void __arch_chacha20_blocks_nostack(u8 *dst_bytes, const u32 *key, + u32 *counter, size_t nblocks); + +#endif /* !__ASSEMBLY__ */ + +#endif /* __ASM_VDSO_GETRANDOM_H */ diff --git a/arch/loongarch/include/asm/vdso/vdso.h b/arch/loongarch/include/asm/vdso/vdso.h index 5a12309d9fb5..a2e24c3007e2 100644 --- a/arch/loongarch/include/asm/vdso/vdso.h +++ b/arch/loongarch/include/asm/vdso/vdso.h @@ -4,6 +4,9 @@ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited */ +#ifndef _ASM_VDSO_VDSO_H +#define _ASM_VDSO_VDSO_H + #ifndef __ASSEMBLY__ #include <asm/asm.h> @@ -16,6 +19,9 @@ struct vdso_pcpu_data { struct loongarch_vdso_data { struct vdso_pcpu_data pdata[NR_CPUS]; +#ifdef CONFIG_VDSO_GETRANDOM + struct vdso_rng_data rng_data; +#endif }; /* @@ -63,3 +69,5 @@ static inline unsigned long get_vdso_data(void) } #endif /* __ASSEMBLY__ */ + +#endif diff --git a/arch/loongarch/kernel/asm-offsets.c b/arch/loongarch/kernel/asm-offsets.c index bee9f7a3108f..86f6d8a6dc23 100644 --- a/arch/loongarch/kernel/asm-offsets.c +++ b/arch/loongarch/kernel/asm-offsets.c @@ -14,6 +14,7 @@ #include <asm/ptrace.h> #include <asm/processor.h> #include <asm/ftrace.h> +#include <asm/vdso/vdso.h> static void __used output_ptreg_defines(void) { @@ -321,3 +322,12 @@ static void __used output_kvm_defines(void) OFFSET(KVM_GPGD, kvm, arch.pgd); BLANK(); } + +#ifdef CONFIG_VDSO_GETRANDOM +static void __used output_vdso_rng_defines(void) +{ + COMMENT("LoongArch VDSO getrandom offsets."); + OFFSET(VDSO_RNG_DATA, loongarch_vdso_data, rng_data); + BLANK(); +} +#endif diff --git a/arch/loongarch/kernel/vdso.c b/arch/loongarch/kernel/vdso.c index 90dfccb41c14..15b65d8e2fdc 100644 --- a/arch/loongarch/kernel/vdso.c +++ b/arch/loongarch/kernel/vdso.c @@ -22,6 +22,7 @@ #include <vdso/helpers.h> #include <vdso/vsyscall.h> #include <vdso/datapage.h> +#include <generated/asm-offsets.h> #include <generated/vdso-offsets.h> extern char vdso_start[], vdso_end[]; @@ -34,6 +35,11 @@ static union { struct loongarch_vdso_data vdata; } loongarch_vdso_data __page_aligned_data; +#ifdef CONFIG_VDSO_GETRANDOM +asm(".globl _vdso_rng_data\n" + ".set _vdso_rng_data, loongarch_vdso_data + " __stringify(VDSO_RNG_DATA)); +#endif + static struct page *vdso_pages[] = { NULL }; struct vdso_data *vdso_data = generic_vdso_data.data; struct vdso_pcpu_data *vdso_pdata = loongarch_vdso_data.vdata.pdata; diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile index 2ddf0480e710..c8c5d9a7c80c 100644 --- a/arch/loongarch/vdso/Makefile +++ b/arch/loongarch/vdso/Makefile @@ -6,6 +6,8 @@ include $(srctree)/lib/vdso/Makefile obj-vdso-y := elf.o vgetcpu.o vgettimeofday.o sigreturn.o +obj-vdso-$(CONFIG_VDSO_GETRANDOM) += vgetrandom.o vgetrandom-chacha.o memset.o + # Common compiler flags between ABIs. ccflags-vdso := \ $(filter -I%,$(KBUILD_CFLAGS)) \ diff --git a/arch/loongarch/vdso/memset.S b/arch/loongarch/vdso/memset.S new file mode 100644 index 000000000000..ec1531683936 --- /dev/null +++ b/arch/loongarch/vdso/memset.S @@ -0,0 +1,24 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * A copy of __memset_generic from arch/loongarch/lib/memset.S for vDSO. + * + * Copyright (C) 2020-2024 Loongson Technology Corporation Limited + */ + +#include <asm/regdef.h> +#include <linux/linkage.h> + +SYM_FUNC_START(memset) + move a3, a0 + beqz a2, 2f + +1: st.b a1, a0, 0 + addi.d a0, a0, 1 + addi.d a2, a2, -1 + bgt a2, zero, 1b + +2: move a0, a3 + jr ra +SYM_FUNC_END(memset) + +.hidden memset diff --git a/arch/loongarch/vdso/vdso.lds.S b/arch/loongarch/vdso/vdso.lds.S index 56ad855896de..2c965a597d9e 100644 --- a/arch/loongarch/vdso/vdso.lds.S +++ b/arch/loongarch/vdso/vdso.lds.S @@ -63,6 +63,7 @@ VERSION __vdso_clock_gettime; __vdso_gettimeofday; __vdso_rt_sigreturn; + __vdso_getrandom; local: *; }; } diff --git a/arch/loongarch/vdso/vgetrandom-chacha.S b/arch/loongarch/vdso/vgetrandom-chacha.S new file mode 100644 index 000000000000..2e42198f2faf --- /dev/null +++ b/arch/loongarch/vdso/vgetrandom-chacha.S @@ -0,0 +1,239 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2024 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved. + */ + +#include <asm/asm.h> +#include <asm/regdef.h> +#include <linux/linkage.h> + +.text + +/* Salsa20 quarter-round */ +.macro QR a b c d + add.w \a, \a, \b + xor \d, \d, \a + rotri.w \d, \d, 16 + + add.w \c, \c, \d + xor \b, \b, \c + rotri.w \b, \b, 20 + + add.w \a, \a, \b + xor \d, \d, \a + rotri.w \d, \d, 24 + + add.w \c, \c, \d + xor \b, \b, \c + rotri.w \b, \b, 25 +.endm + +/* + * Very basic LoongArch 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: + * + * a0: output bytes + * a1: 32-byte key input + * a2: 8-byte counter input/output + * a3: number of 64-byte blocks to write to output + */ +SYM_FUNC_START(__arch_chacha20_blocks_nostack) + +/* We don't need a frame pointer */ +#define s9 fp + +#define output a0 +#define key a1 +#define counter a2 +#define nblocks a3 +#define i a4 +#define state0 s0 +#define state1 s1 +#define state2 s2 +#define state3 s3 +#define state4 s4 +#define state5 s5 +#define state6 s6 +#define state7 s7 +#define state8 s8 +#define state9 s9 +#define state10 a5 +#define state11 a6 +#define state12 a7 +#define state13 t0 +#define state14 t1 +#define state15 t2 +#define cnt_lo t3 +#define cnt_hi t4 +#define copy0 t5 +#define copy1 t6 +#define copy2 t7 + +/* Reuse i as copy3 */ +#define copy3 i + + /* + * The ABI requires s0-s9 saved, and sp aligned to 16-byte. + * This does not violate the stack-less requirement: no sensitive data + * is spilled onto the stack. + */ + PTR_ADDI sp, sp, (-SZREG * 10) & STACK_ALIGN + REG_S s0, sp, 0 + REG_S s1, sp, SZREG + REG_S s2, sp, SZREG * 2 + REG_S s3, sp, SZREG * 3 + REG_S s4, sp, SZREG * 4 + REG_S s5, sp, SZREG * 5 + REG_S s6, sp, SZREG * 6 + REG_S s7, sp, SZREG * 7 + REG_S s8, sp, SZREG * 8 + REG_S s9, sp, SZREG * 9 + + li.w copy0, 0x61707865 + li.w copy1, 0x3320646e + li.w copy2, 0x79622d32 + + ld.w cnt_lo, counter, 0 + ld.w cnt_hi, counter, 4 + +.Lblock: + /* state[0,1,2,3] = "expand 32-byte k" */ + move state0, copy0 + move state1, copy1 + move state2, copy2 + li.w state3, 0x6b206574 + + /* state[4,5,..,11] = key */ + ld.w state4, key, 0 + ld.w state5, key, 4 + ld.w state6, key, 8 + ld.w state7, key, 12 + ld.w state8, key, 16 + ld.w state9, key, 20 + ld.w state10, key, 24 + ld.w state11, key, 28 + + /* state[12,13] = counter */ + move state12, cnt_lo + move state13, cnt_hi + + /* state[14,15] = 0 */ + move state14, zero + move state15, zero + + li.w i, 10 +.Lpermute: + /* odd round */ + QR state0, state4, state8, state12 + QR state1, state5, state9, state13 + QR state2, state6, state10, state14 + QR state3, state7, state11, state15 + + /* even round */ + QR state0, state5, state10, state15 + QR state1, state6, state11, state12 + QR state2, state7, state8, state13 + QR state3, state4, state9, state14 + + addi.w i, i, -1 + bnez i, .Lpermute + + /* copy[3] = "expa" */ + li.w copy3, 0x6b206574 + + /* output[0,1,2,3] = copy[0,1,2,3] + state[0,1,2,3] */ + add.w state0, state0, copy0 + add.w state1, state1, copy1 + add.w state2, state2, copy2 + add.w state3, state3, copy3 + st.w state0, output, 0 + st.w state1, output, 4 + st.w state2, output, 8 + st.w state3, output, 12 + + /* from now on state[0,1,2,3] are scratch registers */ + + /* state[0,1,2,3] = lo32(key) */ + ld.w state0, key, 0 + ld.w state1, key, 4 + ld.w state2, key, 8 + ld.w state3, key, 12 + + /* output[4,5,6,7] = state[0,1,2,3] + state[4,5,6,7] */ + add.w state4, state4, state0 + add.w state5, state5, state1 + add.w state6, state6, state2 + add.w state7, state7, state3 + st.w state4, output, 16 + st.w state5, output, 20 + st.w state6, output, 24 + st.w state7, output, 28 + + /* state[0,1,2,3] = hi32(key) */ + ld.w state0, key, 16 + ld.w state1, key, 20 + ld.w state2, key, 24 + ld.w state3, key, 28 + + /* output[8,9,10,11] = state[0,1,2,3] + state[8,9,10,11] */ + add.w state8, state8, state0 + add.w state9, state9, state1 + add.w state10, state10, state2 + add.w state11, state11, state3 + st.w state8, output, 32 + st.w state9, output, 36 + st.w state10, output, 40 + st.w state11, output, 44 + + /* output[12,13,14,15] = state[12,13,14,15] + [cnt_lo, cnt_hi, 0, 0] */ + add.w state12, state12, cnt_lo + add.w state13, state13, cnt_hi + st.w state12, output, 48 + st.w state13, output, 52 + st.w state14, output, 56 + st.w state15, output, 60 + + /* ++counter */ + addi.w cnt_lo, cnt_lo, 1 + sltui state0, cnt_lo, 1 + add.w cnt_hi, cnt_hi, state0 + + /* output += 64 */ + PTR_ADDI output, output, 64 + /* --nblocks */ + PTR_ADDI nblocks, nblocks, -1 + bnez nblocks, .Lblock + + /* counter = [cnt_lo, cnt_hi] */ + st.w cnt_lo, counter, 0 + st.w cnt_hi, counter, 4 + + /* + * Zero out the potentially sensitive regs, in case nothing uses these + * again. As at now copy[0,1,2,3] just contains "expand 32-byte k" and + * state[0,...,9] are s0-s9 those we'll restore in the epilogue, so we + * only need to zero state[11,...,15]. + */ + move state10, zero + move state11, zero + move state12, zero + move state13, zero + move state14, zero + move state15, zero + + REG_L s0, sp, 0 + REG_L s1, sp, SZREG + REG_L s2, sp, SZREG * 2 + REG_L s3, sp, SZREG * 3 + REG_L s4, sp, SZREG * 4 + REG_L s5, sp, SZREG * 5 + REG_L s6, sp, SZREG * 6 + REG_L s7, sp, SZREG * 7 + REG_L s8, sp, SZREG * 8 + REG_L s9, sp, SZREG * 9 + PTR_ADDI sp, sp, -((-SZREG * 10) & STACK_ALIGN) + + jr ra +SYM_FUNC_END(__arch_chacha20_blocks_nostack) diff --git a/arch/loongarch/vdso/vgetrandom.c b/arch/loongarch/vdso/vgetrandom.c new file mode 100644 index 000000000000..0b3b30ecd68a --- /dev/null +++ b/arch/loongarch/vdso/vgetrandom.c @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024 Xi Ruoyao <xry111@xry111.site>. All Rights Reserved. + */ +#include <linux/types.h> + +#include "../../../../lib/vdso/getrandom.c" + +typeof(__cvdso_getrandom) __vdso_getrandom; + +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); +} + +typeof(__cvdso_getrandom) getrandom + __attribute__((weak, alias("__vdso_getrandom")));
Hook up the generic vDSO implementation to the LoongArch vDSO data page: embed struct vdso_rng_data into struct loongarch_vdso_data, and use assembler hack to resolve the symbol name "_vdso_rng_data" (which is expected by the generic vDSO implementation) to the rng_data field in loongarch_vdso_data. The compiler (GCC 14.2) calls memset() for initializing a "large" struct in a cold path of the generic vDSO getrandom() code. There seems no way to prevent it from calling memset(), and it's a cold path so the performance does not matter, so just provide a naive memset() implementation for vDSO. Signed-off-by: Xi Ruoyao <xry111@xry111.site> --- arch/loongarch/Kconfig | 1 + arch/loongarch/include/asm/vdso/getrandom.h | 47 ++++ arch/loongarch/include/asm/vdso/vdso.h | 8 + arch/loongarch/kernel/asm-offsets.c | 10 + arch/loongarch/kernel/vdso.c | 6 + arch/loongarch/vdso/Makefile | 2 + arch/loongarch/vdso/memset.S | 24 ++ arch/loongarch/vdso/vdso.lds.S | 1 + arch/loongarch/vdso/vgetrandom-chacha.S | 239 ++++++++++++++++++++ arch/loongarch/vdso/vgetrandom.c | 19 ++ 10 files changed, 357 insertions(+) create mode 100644 arch/loongarch/include/asm/vdso/getrandom.h create mode 100644 arch/loongarch/vdso/memset.S create mode 100644 arch/loongarch/vdso/vgetrandom-chacha.S create mode 100644 arch/loongarch/vdso/vgetrandom.c