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selftests: vDSO: check cpu caps before running chacha test

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Some archs -- arm64 and s390x -- implemented chacha using instructions
that are available most places, but aren't always available. The kernel
handles this just fine, but the selftest does not. Check the hwcaps
before running, and skip the test if the cpu doesn't support it. As
well, on s390x, always emit the fallback instructions of an alternative
block, to ensure maximum compatibility.

Co-developed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2024-09-15 01:07:27 +02:00
parent b920aa77be
commit 210860e7f7
2 changed files with 30 additions and 0 deletions
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10
tools/include/asm/alternative.h
View File

@ -2,8 +2,18 @@
#ifndef _TOOLS_ASM_ALTERNATIVE_ASM_H
#define _TOOLS_ASM_ALTERNATIVE_ASM_H
#if defined(__s390x__)
#ifdef __ASSEMBLY__
.macro ALTERNATIVE oldinstr, newinstr, feature
\oldinstr
.endm
#endif
#else
/* Just disable it so we can build arch/x86/lib/memcpy_64.S for perf bench: */
#define ALTERNATIVE #
#endif
#endif

20
tools/testing/selftests/vDSO/vdso_test_chacha.c
View File

@ -5,11 +5,29 @@
#include <tools/le_byteshift.h>
#include <sys/random.h>
#include <sys/auxv.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include "../kselftest.h"
#if defined(__aarch64__)
static bool cpu_has_capabilities(void)
{
return getauxval(AT_HWCAP) & HWCAP_ASIMD;
}
#elif defined(__s390x__)
static bool cpu_has_capabilities(void)
{
return getauxval(AT_HWCAP) & HWCAP_S390_VXRS;
}
#else
static bool cpu_has_capabilities(void)
{
return true;
}
#endif
static uint32_t rol32(uint32_t word, unsigned int shift)
{
return (word << (shift & 31)) | (word >> ((-shift) & 31));
@ -67,6 +85,8 @@ int main(int argc, char *argv[])
uint8_t output1[BLOCK_SIZE * BLOCKS], output2[BLOCK_SIZE * BLOCKS];
ksft_print_header();
if (!cpu_has_capabilities())
ksft_exit_skip("Required CPU capabilities missing\n");
ksft_set_plan(1);
for (unsigned int trial = 0; trial < TRIALS; ++trial) {