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

Adhemerval Zanella Netto
2024-08-27T14:30:25Z

On 27/08/24 11:28, Jason A. Donenfeld wrote:
> On Tue, Aug 27, 2024 at 11:14:27AM -0300, Adhemerval Zanella Netto wrote:
>>
>>
>> On 27/08/24 11:10, Christophe Leroy wrote:
>>>
>>>
>>> Le 27/08/2024 à 16:01, Adhemerval Zanella Netto a écrit :
>>>> [Vous ne recevez pas souvent de courriers de adhemerval.zanella@linaro.org. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>>>
>>>> On 27/08/24 11:00, Christophe Leroy wrote:
>>>>>
>>>>>
>>>>> Le 27/08/2024 à 15:39, Adhemerval Zanella Netto a écrit :
>>>>>> [Vous ne recevez pas souvent de courriers de adhemerval.zanella@linaro.org. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>>>>>
>>>>>> On 27/08/24 10:34, Jason A. Donenfeld wrote:
>>>>>>> On Tue, Aug 27, 2024 at 10:17:18AM -0300, Adhemerval Zanella Netto wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 26/08/24 17:27, Jason A. Donenfeld wrote:
>>>>>>>>> Hi Adhemerval,
>>>>>>>>>
>>>>>>>>> Thanks for posting this! Exciting to have it here.
>>>>>>>>>
>>>>>>>>> Just some small nits for now:
>>>>>>>>>
>>>>>>>>> On Mon, Aug 26, 2024 at 06:10:40PM +0000, Adhemerval Zanella wrote:
>>>>>>>>>> +static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags)
>>>>>>>>>> +{
>>>>>>>>>> +  register long int x8 asm ("x8") = __NR_getrandom;
>>>>>>>>>> +  register long int x0 asm ("x0") = (long int) buffer;
>>>>>>>>>> +  register long int x1 asm ("x1") = (long int) len;
>>>>>>>>>> +  register long int x2 asm ("x2") = (long int) flags;
>>>>>>>>>
>>>>>>>>> Usually it's written just as `long` or `unsigned long`, and likewise
>>>>>>>>> with the cast. Also, no space after the cast.
>>>>>>>>
>>>>>>>> Ack.
>>>>>>>>
>>>>>>>>>
>>>>>>>>>> +#define __VDSO_RND_DATA_OFFSET  480
>>>>>>>>>
>>>>>>>>> This is the size of the data currently there?
>>>>>>>>
>>>>>>>> Yes, I used the same strategy x86 did.
>>>>>>>>
>>>>>>>>>
>>>>>>>>>>    #include <asm/page.h>
>>>>>>>>>>    #include <asm/vdso.h>
>>>>>>>>>>    #include <asm-generic/vmlinux.lds.h>
>>>>>>>>>> +#include <vdso/datapage.h>
>>>>>>>>>> +#include <asm/vdso/vsyscall.h>
>>>>>>>>>
>>>>>>>>> Possible to keep the asm/ together?
>>>>>>>>
>>>>>>>> Ack.
>>>>>>>>
>>>>>>>>>
>>>>>>>>>> + * ARM64 ChaCha20 implementation meant for vDSO.  Produces a given positive
>>>>>>>>>> + * number of blocks of output with nonnce 0, taking an input key and 8-bytes
>>>>>>>>>
>>>>>>>>> nonnce -> nonce
>>>>>>>>
>>>>>>>> Ack.
>>>>>>>>
>>>>>>>>>
>>>>>>>>>> -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/)
>>>>>>>>>>    SODIUM := $(shell pkg-config --libs libsodium 2>/dev/null)
>>>>>>>>>>
>>>>>>>>>>    TEST_GEN_PROGS := vdso_test_gettimeofday
>>>>>>>>>> @@ -11,7 +11,7 @@ ifeq ($(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, $(uname_M)))
>>>>>>>>>>    TEST_GEN_PROGS += vdso_test_getrandom
>>>>>>>>>>    ifneq ($(SODIUM),)
>>>>>>>>>>    TEST_GEN_PROGS += vdso_test_chacha
>>>>>>>>>
>>>>>>>>> You'll need to add the symlink to get the chacha selftest running:
>>>>>>>>>
>>>>>>>>>     $ ln -s ../../../arch/arm64/kernel/vdso tools/arch/arm64/vdso
>>>>>>>>>     $ git add tools/arch/arm64/vdso
>>>>>>>>>
>>>>>>>>> Also, can you confirm that the chacha selftest runs and works?
>>>>>>>>
>>>>>>>> Yes, last time I has to built it manually since the Makefile machinery seem
>>>>>>>> to be broken even on x86_64.  In a Ubuntu vm I have:
>>>>>>>>
>>>>>>>> tools/testing/selftests/vDSO$ make
>>>>>>>>     CC       vdso_test_gettimeofday
>>>>>>>>     CC       vdso_test_getcpu
>>>>>>>>     CC       vdso_test_abi
>>>>>>>>     CC       vdso_test_clock_getres
>>>>>>>>     CC       vdso_standalone_test_x86
>>>>>>>>     CC       vdso_test_correctness
>>>>>>>>     CC       vdso_test_getrandom
>>>>>>>>     CC       vdso_test_chacha
>>>>>>>> In file included from /home/azanella/Projects/linux/linux-git/include/linux/limits.h:7,
>>>>>>>>                    from /usr/include/x86_64-linux-gnu/bits/local_lim.h:38,
>>>>>>>>                    from /usr/include/x86_64-linux-gnu/bits/posix1_lim.h:161,
>>>>>>>>                    from /usr/include/limits.h:195,
>>>>>>>>                    from /usr/lib/gcc/x86_64-linux-gnu/13/include/limits.h:205,
>>>>>>>>                    from /usr/lib/gcc/x86_64-linux-gnu/13/include/syslimits.h:7,
>>>>>>>>                    from /usr/lib/gcc/x86_64-linux-gnu/13/include/limits.h:34,
>>>>>>>>                    from /usr/include/sodium/export.h:7,
>>>>>>>>                    from /usr/include/sodium/crypto_stream_chacha20.h:14,
>>>>>>>>                    from vdso_test_chacha.c:6:
>>>>>>>> /usr/include/x86_64-linux-gnu/bits/xopen_lim.h:99:6: error: missing binary operator before token "("
>>>>>>>>      99 | # if INT_MAX == 32767
>>>>>>>>         |      ^~~~~~~
>>>>>>>> /usr/include/x86_64-linux-gnu/bits/xopen_lim.h:102:7: error: missing binary operator before token "("
>>>>>>>>     102 | #  if INT_MAX == 2147483647
>>>>>>>>         |       ^~~~~~~
>>>>>>>> /usr/include/x86_64-linux-gnu/bits/xopen_lim.h:126:6: error: missing binary operator before token "("
>>>>>>>>     126 | # if LONG_MAX == 2147483647
>>>>>>>>         |      ^~~~~~~~
>>>>>>>> make: *** [../lib.mk:222: /home/azanella/Projects/linux/linux-git/tools/testing/selftests/vDSO/vdso_test_chacha] Error 1
>>>>>>>
>>>>>>> You get that even with the latest random.git? I thought Christophe's
>>>>>>> patch fixed that, but maybe not and I should just remove the dependency
>>>>>>> on the sodium header instead.
>>>>>>
>>>>>> On x86_64 I tested with Linux master.  With random.git it is a different issue:
>>>>>>
>>>>>> linux-git/tools/testing/selftests/vDSO$ make
>>>>>>     CC       vdso_test_gettimeofday
>>>>>>     CC       vdso_test_getcpu
>>>>>>     CC       vdso_test_abi
>>>>>>     CC       vdso_test_clock_getres
>>>>>>     CC       vdso_standalone_test_x86
>>>>>>     CC       vdso_test_correctness
>>>>>>     CC       vdso_test_getrandom
>>>>>>     CC       vdso_test_chacha
>>>>>> /usr/bin/ld: /tmp/ccKpjnSM.o: in function `main':
>>>>>> vdso_test_chacha.c:(.text+0x276): undefined reference to `crypto_stream_chacha20'
>>>>>> collect2: error: ld returned 1 exit status
>>>>>>
>>>>>> If I move -lsodium to the end of the compiler command it works.
>>>>>>
>>>>>>
>>>>>
>>>>> Try a "make clean" maybe ?
>>>>>
>>>>> I have Fedora 38 and no build problem with latest random tree:
>>>>>
>>>>> $ make V=1
>>>>> gcc -std=gnu99 -D_GNU_SOURCE=    vdso_test_gettimeofday.c parse_vdso.c -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_gettimeofday
>>>>> gcc -std=gnu99 -D_GNU_SOURCE=    vdso_test_getcpu.c parse_vdso.c  -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_getcpu
>>>>> gcc -std=gnu99 -D_GNU_SOURCE=    vdso_test_abi.c parse_vdso.c  -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_abi
>>>>> gcc -std=gnu99 -D_GNU_SOURCE=    vdso_test_clock_getres.c  -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_clock_getres
>>>>> gcc -std=gnu99 -D_GNU_SOURCE= -nostdlib -fno-asynchronous-unwind-tables -fno-stack-protector    vdso_standalone_test_x86.c parse_vdso.c  -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_standalone_test_x86
>>>>> gcc -std=gnu99 -D_GNU_SOURCE=  -ldl  vdso_test_correctness.c  -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_correctness
>>>>> gcc -std=gnu99 -D_GNU_SOURCE= -isystem /home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include -isystem /home/chleroy/linux-powerpc/tools/testing/selftests/../../../include/uapi    vdso_test_getrandom.c parse_vdso.c  -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_getrandom
>>>>> gcc -std=gnu99 -D_GNU_SOURCE= -idirafter /home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include -idirafter /home/chleroy/linux-powerpc/tools/testing/selftests/../../../arch/x86/include -idirafter /home/chleroy/linux-powerpc/tools/testing/selftests/../../../include -D__ASSEMBLY__ -DBULID_VDSO -DCONFIG_FUNCTION_ALIGNMENT=0 -Wa,--noexecstack -lsodium     vdso_test_chacha.c /home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/arch/x86/vdso/vgetrandom-chacha.S  -o /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_chacha
>>>>> $
>>>>
>>>> It is a clean tree (git clean -dfx), and I take there is no need to build a kernel
>>>> prior hand.
>>>
>>> I meeant 'make clean'
>>>
>>>
>>> Right, I have not built any x86 kernel at the moment.
>>>
>>> Just :
>>> $ pwd
>>> /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO
>>>
>>> $ make clean
>>>
>>> then
>>>
>>> $ make V=1
>>
>> The issue is Ubuntu linker is configure to use --as-needed by default, this
>> patch fixes the issue:
>>
>> diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
>> index 10ffdda3f2fa..151baf650e4c 100644
>> --- a/tools/testing/selftests/vDSO/Makefile
>> +++ b/tools/testing/selftests/vDSO/Makefile
>> @@ -45,4 +45,4 @@ $(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
>> -idirafter $(top_srcdir)/arch/$(ARCH)/include \
>> -idirafter $(top_srcdir)/include \
>> -D__ASSEMBLY__ -DBULID_VDSO -DCONFIG_FUNCTION_ALIGNMENT=0 \
>> - -Wa,--noexecstack $(SODIUM)
>> + -Wa,--noexecstack -Wl,-no-as-needed $(SODIUM)
>
> Oh, it's an as-needed thing. In that case, does this fix it for you?
>
> diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
> index 10ffdda3f2fa..834aa862ba2c 100644
> --- a/tools/testing/selftests/vDSO/Makefile
> +++ b/tools/testing/selftests/vDSO/Makefile
> @@ -1,7 +1,8 @@
> # 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/)
> -SODIUM := $(shell pkg-config --libs libsodium 2>/dev/null)
> +SODIUM_LIBS := $(shell pkg-config --libs libsodium 2>/dev/null)
> +SODIUM_CFLAGS := $(shell pkg-config --cflags libsodium 2>/dev/null)
>
> TEST_GEN_PROGS := vdso_test_gettimeofday
> TEST_GEN_PROGS += vdso_test_getcpu
> @@ -13,7 +14,7 @@ endif
> TEST_GEN_PROGS += vdso_test_correctness
> ifeq ($(uname_M),x86_64)
> TEST_GEN_PROGS += vdso_test_getrandom
> -ifneq ($(SODIUM),)
> +ifneq ($(SODIUM_LIBS),)
> TEST_GEN_PROGS += vdso_test_chacha
> endif
> endif
> @@ -41,8 +42,9 @@ $(OUTPUT)/vdso_test_getrandom: CFLAGS += -isystem $(top_srcdir)/tools/include \
> -isystem $(top_srcdir)/include/uapi
>
> $(OUTPUT)/vdso_test_chacha: $(top_srcdir)/tools/arch/$(ARCH)/vdso/vgetrandom-chacha.S
> +$(OUTPUT)/vdso_test_chacha: LDLIBS += $(SODIUM_LIBS)
> $(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
> -idirafter $(top_srcdir)/arch/$(ARCH)/include \
> -idirafter $(top_srcdir)/include \
> -D__ASSEMBLY__ -DBULID_VDSO -DCONFIG_FUNCTION_ALIGNMENT=0 \
> - -Wa,--noexecstack $(SODIUM)
> + -Wa,--noexecstack $(SODIUM_CFLAGS)
>

Nops, 'pkg-config --cflags libsodium' is empty. The -Wl,-no-as-needed is simpler
I think.