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s390: add HWCAP_S390_PCI_MIO to ELF hwcaps

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In order to support the use of enhanced PCI instructions in both kernel-
and userspace we need both hardware support and proper setup in the
kernel. The latter can be toggled off with the pci=nomio command line
option.

Thus availability of this feature in userspace depends on all of kernel
configuration (CONFIG_PCI), hardware support and the current kernel
command line and can thus not rely solely on a facility bit. Instead
let's introduce a new ELF hardware capability bit HWCAP_S390_PCI_MIO to
tell userspace whether these PCI instructions can be used.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Niklas Schnelle 2021-07-08 15:43:13 +02:00 committed by Heiko Carstens
parent 3322ba0d7b
commit 7e8403ecaf
3 changed files with 4 additions and 1 deletions
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1
arch/s390/include/asm/elf.h
View File

@ -113,6 +113,7 @@
#define HWCAP_S390_DFLT 262144
#define HWCAP_S390_VXRS_PDE2 524288
#define HWCAP_S390_NNPA 1048576
#define HWCAP_S390_PCI_MIO 2097152
/* Internal bits, not exposed via elf */
#define HWCAP_INT_SIE 1UL

2
arch/s390/kernel/processor.c
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@ -115,7 +115,7 @@ static void show_cpu_summary(struct seq_file *m, void *v)
static const char *hwcap_str[] = {
"esan3", "zarch", "stfle", "msa", "ldisp", "eimm", "dfp",
"edat", "etf3eh", "highgprs", "te", "vx", "vxd", "vxe", "gs",
"vxe2", "vxp", "sort", "dflt", "vxp2", "nnpa"
"vxe2", "vxp", "sort", "dflt", "vxp2", "nnpa", "pcimio"
};
static const char * const int_hwcap_str[] = {
"sie"

2
arch/s390/kernel/setup.c
View File

@ -964,6 +964,8 @@ static int __init setup_hwcaps(void)
*/
if (MACHINE_HAS_GS)
elf_hwcap |= HWCAP_S390_GS;
if (MACHINE_HAS_PCI_MIO)
elf_hwcap |= HWCAP_S390_PCI_MIO;
get_cpu_id(&cpu_id);
add_device_randomness(&cpu_id, sizeof(cpu_id));