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

Adhemerval Zanella Netto
2024-08-27T14:14:35Z

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)