From 724dc336b79ff965bd5773257642685cf33ed9af Mon Sep 17 00:00:00 2001
From: Vasily Gorbik <gor@linux.ibm.com>
Date: Thu, 8 Aug 2019 20:09:08 +0200
Subject: [PATCH] s390/startup: add pgm check info printing
Try to print out startup pgm check info including exact linux kernel
version, pgm interruption code and ilc, psw and general registers. Like
the following:
Linux version 5.3.0-rc7-07282-ge7b4d41d61bd-dirty (gor@tuxmaker) #3 SMP PREEMPT Thu Sep 5 16:07:34 CEST 2019
Kernel fault: interruption code 0005 ilc:2
PSW : 0000000180000000 0000000000012e52
R:0 T:0 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:0 PM:0 RI:0 EA:3
GPRS: 0000000000000000 00ffffffffffffff 0000000000000000 0000000000019a58
000000000000bf68 0000000000000000 0000000000000000 0000000000000000
0000000000000000 0000000000000000 000000000001a041 0000000000000000
0000000004c9c000 0000000000010070 0000000000012e42 000000000000beb0
This info makes it apparent that kernel startup failed and might help
to understand what went wrong without actual standalone dump.
Printing code runs on its own stack of 1 page (at unused 0x5000), which
should be sufficient for sclp_early_printk usage (typical stack usage
observed has been around 512 bytes).
The code has pgm check recursion prevention, despite pgm check info
printing failure (follow on pgm check) or success it restores original
faulty psw and gprs and does disabled wait.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---
arch/s390/boot/Makefile | 2 +-
arch/s390/boot/boot.h | 1 +
arch/s390/boot/head.S | 10 +++-
arch/s390/boot/pgm_check_info.c | 90 +++++++++++++++++++++++++++++++++
4 files changed, 101 insertions(+), 2 deletions(-)
create mode 100644 arch/s390/boot/pgm_check_info.c
diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile
index 4cf0bddb7d92e..e2c47d3a1c891 100644
--- a/arch/s390/boot/Makefile
+++ b/arch/s390/boot/Makefile
@@ -36,7 +36,7 @@ CFLAGS_sclp_early_core.o += -I$(srctree)/drivers/s390/char
obj-y := head.o als.o startup.o mem_detect.o ipl_parm.o ipl_report.o
obj-y += string.o ebcdic.o sclp_early_core.o mem.o ipl_vmparm.o cmdline.o
-obj-y += version.o ctype.o text_dma.o
+obj-y += version.o pgm_check_info.o ctype.o text_dma.o
obj-$(CONFIG_PROTECTED_VIRTUALIZATION_GUEST) += uv.o
obj-$(CONFIG_RELOCATABLE) += machine_kexec_reloc.o
obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
diff --git a/arch/s390/boot/boot.h b/arch/s390/boot/boot.h
index 082905d97309c..1f7a8d4aff284 100644
--- a/arch/s390/boot/boot.h
+++ b/arch/s390/boot/boot.h
@@ -9,6 +9,7 @@ void setup_boot_command_line(void);
void parse_boot_command_line(void);
void setup_memory_end(void);
void print_missing_facilities(void);
+void print_pgm_check_info(void);
unsigned long get_random_base(unsigned long safe_addr);
extern int kaslr_enabled;
diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index 5b79ae7b44f3f..4b86a8d3c1219 100644
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -365,12 +365,20 @@ ENTRY(startup_pgm_check_handler)
stctg %c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r1)
mvc __LC_GPREGS_SAVE_AREA-4095(128,%r1),__LC_SAVE_AREA_SYNC
mvc __LC_PSW_SAVE_AREA-4095(16,%r1),__LC_PGM_OLD_PSW
- lg %r1,__LC_SAVE_AREA_SYNC+8
mvc __LC_RETURN_PSW(16),__LC_PGM_OLD_PSW
ni __LC_RETURN_PSW,0xfc # remove IO and EX bits
ni __LC_RETURN_PSW+1,0xfb # remove MCHK bit
oi __LC_RETURN_PSW+1,0x2 # set wait state bit
+ larl %r2,.Lold_psw_disabled_wait
+ stg %r2,__LC_PGM_NEW_PSW+8
+ l %r15,.Ldump_info_stack-.Lold_psw_disabled_wait(%r2)
+ brasl %r14,print_pgm_check_info
+.Lold_psw_disabled_wait:
+ la %r1,4095
+ lmg %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)
lpswe __LC_RETURN_PSW # disabled wait
+.Ldump_info_stack:
+ .long 0x5000 + PAGE_SIZE - STACK_FRAME_OVERHEAD
ENDPROC(startup_pgm_check_handler)
#
diff --git a/arch/s390/boot/pgm_check_info.c b/arch/s390/boot/pgm_check_info.c
new file mode 100644
index 0000000000000..83b5b7915c32d
--- /dev/null
+++ b/arch/s390/boot/pgm_check_info.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <asm/lowcore.h>
+#include <asm/sclp.h>
+#include "boot.h"
+
+const char hex_asc[] = "0123456789abcdef";
+
+#define add_val_as_hex(dst, val) \
+ __add_val_as_hex(dst, (const unsigned char *)&val, sizeof(val))
+
+static char *__add_val_as_hex(char *dst, const unsigned char *src, size_t count)
+{
+ while (count--)
+ dst = hex_byte_pack(dst, *src++);
+ return dst;
+}
+
+static char *add_str(char *dst, char *src)
+{
+ strcpy(dst, src);
+ return dst + strlen(dst);
+}
+
+void print_pgm_check_info(void)
+{
+ struct psw_bits *psw = &psw_bits(S390_lowcore.psw_save_area);
+ unsigned short ilc = S390_lowcore.pgm_ilc >> 1;
+ char buf[256];
+ int row, col;
+ char *p;
+
+ add_str(buf, "Linux version ");
+ strlcat(buf, kernel_version, sizeof(buf));
+ sclp_early_printk(buf);
+
+ p = add_str(buf, "Kernel fault: interruption code ");
+ p = add_val_as_hex(buf + strlen(buf), S390_lowcore.pgm_code);
+ p = add_str(p, " ilc:");
+ *p++ = hex_asc_lo(ilc);
+ add_str(p, "\n");
+ sclp_early_printk(buf);
+
+ p = add_str(buf, "PSW : ");
+ p = add_val_as_hex(p, S390_lowcore.psw_save_area.mask);
+ p = add_str(p, " ");
+ p = add_val_as_hex(p, S390_lowcore.psw_save_area.addr);
+ add_str(p, "\n");
+ sclp_early_printk(buf);
+
+ p = add_str(buf, " R:");
+ *p++ = hex_asc_lo(psw->per);
+ p = add_str(p, " T:");
+ *p++ = hex_asc_lo(psw->dat);
+ p = add_str(p, " IO:");
+ *p++ = hex_asc_lo(psw->io);
+ p = add_str(p, " EX:");
+ *p++ = hex_asc_lo(psw->ext);
+ p = add_str(p, " Key:");
+ *p++ = hex_asc_lo(psw->key);
+ p = add_str(p, " M:");
+ *p++ = hex_asc_lo(psw->mcheck);
+ p = add_str(p, " W:");
+ *p++ = hex_asc_lo(psw->wait);
+ p = add_str(p, " P:");
+ *p++ = hex_asc_lo(psw->pstate);
+ p = add_str(p, " AS:");
+ *p++ = hex_asc_lo(psw->as);
+ p = add_str(p, " CC:");
+ *p++ = hex_asc_lo(psw->cc);
+ p = add_str(p, " PM:");
+ *p++ = hex_asc_lo(psw->pm);
+ p = add_str(p, " RI:");
+ *p++ = hex_asc_lo(psw->ri);
+ p = add_str(p, " EA:");
+ *p++ = hex_asc_lo(psw->eaba);
+ add_str(p, "\n");
+ sclp_early_printk(buf);
+
+ for (row = 0; row < 4; row++) {
+ p = add_str(buf, row == 0 ? "GPRS:" : " ");
+ for (col = 0; col < 4; col++) {
+ p = add_str(p, " ");
+ p = add_val_as_hex(p, S390_lowcore.gpregs_save_area[row * 4 + col]);
+ }
+ add_str(p, "\n");
+ sclp_early_printk(buf);
+ }
+}
--
2.30.2