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s390/spinlock: remove compare and delay instruction

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The CAD instruction never worked quite as expected for the spinlock
code. It has been disabled by default with git commit 61b0b01686,
if the "cad" kernel parameter is specified it is enabled for both user
space and the spinlock code. Leave the option to enable the instruction
for user space but remove it from the spinlock code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2017-03-24 17:00:45 +01:00
parent 02c503ff23
commit b13de4b7ad
3 changed files with 13 additions and 45 deletions
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19
arch/s390/kernel/early.c
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@@ -434,23 +434,16 @@ early_param("noexec", noexec_setup);
static int __init cad_setup(char *str)
{
int val;
bool enabled;
int rc;
get_option(&str, &val);
if (val && test_facility(128))
S390_lowcore.machine_flags |= MACHINE_FLAG_CAD;
return 0;
}
early_param("cad", cad_setup);
static int __init cad_init(void)
{
if (MACHINE_HAS_CAD)
rc = kstrtobool(str, &enabled);
if (!rc && enabled && test_facility(128))
/* Enable problem state CAD. */
__ctl_set_bit(2, 3);
return 0;
return rc;
}
early_initcall(cad_init);
early_param("cad", cad_setup);
static __init void memmove_early(void *dst, const void *src, size_t n)
{