s390/cmma: move parsing of cmma kernel parameter to early boot code

The "cmma=" kernel command line parameter needs to be parsed early for
upcoming changes. Therefore move the parsing code.

Note that EX_TABLE handling of cmma_test_essa() needs to be open-coded,
since the early boot code doesn't have infrastructure for handling expected
exceptions.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

2 files changed, 52 insertions, 0 deletions

diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c
index 7b7521762633..2ab4872fbee1 100644
--- a/arch/s390/boot/ipl_parm.c
+++ b/arch/s390/boot/ipl_parm.c
@@ -3,6 +3,7 @@
 #include <linux/init.h>
 #include <linux/ctype.h>
 #include <linux/pgtable.h>
+#include <asm/page-states.h>
 #include <asm/ebcdic.h>
 #include <asm/sclp.h>
 #include <asm/sections.h>
@@ -24,6 +25,7 @@ unsigned int __bootdata_preserved(zlib_dfltcc_support) = ZLIB_DFLTCC_FULL;
 struct ipl_parameter_block __bootdata_preserved(ipl_block);
 int __bootdata_preserved(ipl_block_valid);
 int __bootdata_preserved(__kaslr_enabled);
+int __bootdata_preserved(cmma_flag) = 1;
 
 unsigned long vmalloc_size = VMALLOC_DEFAULT_SIZE;
 unsigned long memory_limit;
@@ -295,6 +297,12 @@ void parse_boot_command_line(void)
 		if (!strcmp(param, "nokaslr"))
 			__kaslr_enabled = 0;
 
+		if (!strcmp(param, "cmma")) {
+			rc = kstrtobool(val, &enabled);
+			if (!rc && !enabled)
+				cmma_flag = 0;
+		}
+
 #if IS_ENABLED(CONFIG_KVM)
 		if (!strcmp(param, "prot_virt")) {
 			rc = kstrtobool(val, &enabled);
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 8826c4f18645..8104e0e3d188 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/string.h>
 #include <linux/elf.h>
+#include <asm/page-states.h>
 #include <asm/boot_data.h>
 #include <asm/sections.h>
 #include <asm/maccess.h>
@@ -57,6 +58,48 @@ static void detect_facilities(void)
 		machine.has_nx = 1;
 }
 
+static int cmma_test_essa(void)
+{
+	unsigned long reg1, reg2, tmp = 0;
+	int rc = 1;
+	psw_t old;
+
+	/* Test ESSA_GET_STATE */
+	asm volatile(
+		"	mvc	0(16,%[psw_old]),0(%[psw_pgm])\n"
+		"	epsw	%[reg1],%[reg2]\n"
+		"	st	%[reg1],0(%[psw_pgm])\n"
+		"	st	%[reg2],4(%[psw_pgm])\n"
+		"	larl	%[reg1],1f\n"
+		"	stg	%[reg1],8(%[psw_pgm])\n"
+		"	.insn	rrf,0xb9ab0000,%[tmp],%[tmp],%[cmd],0\n"
+		"	la	%[rc],0\n"
+		"1:	mvc	0(16,%[psw_pgm]),0(%[psw_old])\n"
+		: [reg1] "=&d" (reg1),
+		  [reg2] "=&a" (reg2),
+		  [rc] "+&d" (rc),
+		  [tmp] "=&d" (tmp),
+		  "+Q" (S390_lowcore.program_new_psw),
+		  "=Q" (old)
+		: [psw_old] "a" (&old),
+		  [psw_pgm] "a" (&S390_lowcore.program_new_psw),
+		  [cmd] "i" (ESSA_GET_STATE)
+		: "cc", "memory");
+	return rc;
+}
+
+static void cmma_init(void)
+{
+	if (!cmma_flag)
+		return;
+	if (cmma_test_essa()) {
+		cmma_flag = 0;
+		return;
+	}
+	if (test_facility(147))
+		cmma_flag = 2;
+}
+
 static void setup_lpp(void)
 {
 	S390_lowcore.current_pid = 0;
@@ -306,6 +349,7 @@ void startup_kernel(void)
 	setup_boot_command_line();
 	parse_boot_command_line();
 	detect_facilities();
+	cmma_init();
 	sanitize_prot_virt_host();
 	max_physmem_end = detect_max_physmem_end();
 	setup_ident_map_size(max_physmem_end);