diff options
| author | Heiko Carstens <hca@linux.ibm.com> | 2024-08-01 17:16:12 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2024-08-22 19:28:11 +0200 |
| commit | 6708948e361fc1eea858f8ce333c1aab7411c114 (patch) | |
| tree | e7ce69ccdb6e3c98a5a9fafb480b3f4d6c4e8818 | |
| parent | 0bc6a69f5fda17c907dfdf5850a293d13010e9e5 (diff) | |
| download | lwn-6708948e361fc1eea858f8ce333c1aab7411c114.tar.gz lwn-6708948e361fc1eea858f8ce333c1aab7411c114.zip | |
s390/early: Dump register contents and call trace for early crashes
If the early program check handler cannot resolve a program check dump
register contents and a call trace to the console before loading a disabled
wait psw. This makes debugging much easier.
Emit an extra message with early_printk() for cases where regular printk()
via the early console is not yet working so that at least some information
is available.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/setup.h | 2 | ||||
| -rw-r--r-- | arch/s390/kernel/early.c | 10 | ||||
| -rw-r--r-- | arch/s390/kernel/early_printk.c | 16 |
3 files changed, 24 insertions, 4 deletions
diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h index 8505737712ee..50b943f30155 100644 --- a/arch/s390/include/asm/setup.h +++ b/arch/s390/include/asm/setup.h @@ -115,6 +115,8 @@ extern unsigned int console_irq; #define SET_CONSOLE_VT220 do { console_mode = 4; } while (0) #define SET_CONSOLE_HVC do { console_mode = 5; } while (0) +void register_early_console(void); + #ifdef CONFIG_VMCP void vmcp_cma_reserve(void); #else diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index 25ce02be77a3..cc4264d23019 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -7,6 +7,7 @@ #define KMSG_COMPONENT "setup" #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt +#include <linux/sched/debug.h> #include <linux/compiler.h> #include <linux/init.h> #include <linux/errno.h> @@ -191,6 +192,15 @@ void __init __do_early_pgm_check(struct pt_regs *regs) } if (fixup_exception(regs)) return; + /* + * Unhandled exception - system cannot continue but try to get some + * helpful messages to the console. Use early_printk() to print + * some basic information in case it is too early for printk(). + */ + register_early_console(); + early_printk("PANIC: early exception %04x PSW: %016lx %016lx\n", + regs->int_code & 0xffff, regs->psw.mask, regs->psw.addr); + show_regs(regs); disabled_wait(); } diff --git a/arch/s390/kernel/early_printk.c b/arch/s390/kernel/early_printk.c index d9d53f44008a..cefe020a3be3 100644 --- a/arch/s390/kernel/early_printk.c +++ b/arch/s390/kernel/early_printk.c @@ -6,6 +6,7 @@ #include <linux/console.h> #include <linux/kernel.h> #include <linux/init.h> +#include <asm/setup.h> #include <asm/sclp.h> static void sclp_early_write(struct console *con, const char *s, unsigned int len) @@ -20,6 +21,16 @@ static struct console sclp_early_console = { .index = -1, }; +void __init register_early_console(void) +{ + if (early_console) + return; + if (!sclp.has_linemode && !sclp.has_vt220) + return; + early_console = &sclp_early_console; + register_console(early_console); +} + static int __init setup_early_printk(char *buf) { if (early_console) @@ -27,10 +38,7 @@ static int __init setup_early_printk(char *buf) /* Accept only "earlyprintk" and "earlyprintk=sclp" */ if (buf && !str_has_prefix(buf, "sclp")) return 0; - if (!sclp.has_linemode && !sclp.has_vt220) - return 0; - early_console = &sclp_early_console; - register_console(early_console); + register_early_console(); return 0; } early_param("earlyprintk", setup_early_printk); |