Commit 7e8403ec authored Jul 08, 2021 by Niklas Schnelle Committed by Heiko Carstens Jul 27, 2021

s390: add HWCAP_S390_PCI_MIO to ELF hwcaps



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>

parent 3322ba0d

arch/s390/include/asm/elf.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

arch/s390/kernel/processor.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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"

arch/s390/kernel/setup.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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));