diff options
| -rw-r--r-- | arch/i386/kernel/vmlinux.lds.S | 7 | ||||
| -rw-r--r-- | drivers/base/power/Makefile | 1 | ||||
| -rw-r--r-- | drivers/base/power/trace.c | 228 | ||||
| -rw-r--r-- | include/asm-generic/rtc.h | 7 | ||||
| -rw-r--r-- | include/linux/resume-trace.h | 30 | ||||
| -rw-r--r-- | kernel/power/Kconfig | 9 |
6 files changed, 279 insertions, 3 deletions
diff --git a/arch/i386/kernel/vmlinux.lds.S b/arch/i386/kernel/vmlinux.lds.S index 8831303a473..7512f39c9f2 100644 --- a/arch/i386/kernel/vmlinux.lds.S +++ b/arch/i386/kernel/vmlinux.lds.S @@ -37,6 +37,13 @@ SECTIONS RODATA + . = ALIGN(4); + __tracedata_start = .; + .tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) { + *(.tracedata) + } + __tracedata_end = .; + /* writeable */ .data : AT(ADDR(.data) - LOAD_OFFSET) { /* Data */ *(.data) diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile index ceeeba2c56c..91f230939c1 100644 --- a/drivers/base/power/Makefile +++ b/drivers/base/power/Makefile @@ -1,5 +1,6 @@ obj-y := shutdown.o obj-$(CONFIG_PM) += main.o suspend.o resume.o runtime.o sysfs.o +obj-$(CONFIG_PM_TRACE) += trace.o ifeq ($(CONFIG_DEBUG_DRIVER),y) EXTRA_CFLAGS += -DDEBUG diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c new file mode 100644 index 00000000000..a9ab30fefff --- /dev/null +++ b/drivers/base/power/trace.c @@ -0,0 +1,228 @@ +/* + * drivers/base/power/trace.c + * + * Copyright (C) 2006 Linus Torvalds + * + * Trace facility for suspend/resume problems, when none of the + * devices may be working. + */ + +#include <linux/resume-trace.h> +#include <linux/rtc.h> + +#include <asm/rtc.h> + +#include "power.h" + +/* + * Horrid, horrid, horrid. + * + * It turns out that the _only_ piece of hardware that actually + * keeps its value across a hard boot (and, more importantly, the + * POST init sequence) is literally the realtime clock. + * + * Never mind that an RTC chip has 114 bytes (and often a whole + * other bank of an additional 128 bytes) of nice SRAM that is + * _designed_ to keep data - the POST will clear it. So we literally + * can just use the few bytes of actual time data, which means that + * we're really limited. + * + * It means, for example, that we can't use the seconds at all + * (since the time between the hang and the boot might be more + * than a minute), and we'd better not depend on the low bits of + * the minutes either. + * + * There are the wday fields etc, but I wouldn't guarantee those + * are dependable either. And if the date isn't valid, either the + * hw or POST will do strange things. + * + * So we're left with: + * - year: 0-99 + * - month: 0-11 + * - day-of-month: 1-28 + * - hour: 0-23 + * - min: (0-30)*2 + * + * Giving us a total range of 0-16128000 (0xf61800), ie less + * than 24 bits of actual data we can save across reboots. + * + * And if your box can't boot in less than three minutes, + * you're screwed. + * + * Now, almost 24 bits of data is pitifully small, so we need + * to be pretty dense if we want to use it for anything nice. + * What we do is that instead of saving off nice readable info, + * we save off _hashes_ of information that we can hopefully + * regenerate after the reboot. + * + * In particular, this means that we might be unlucky, and hit + * a case where we have a hash collision, and we end up not + * being able to tell for certain exactly which case happened. + * But that's hopefully unlikely. + * + * What we do is to take the bits we can fit, and split them + * into three parts (16*997*1009 = 16095568), and use the values + * for: + * - 0-15: user-settable + * - 0-996: file + line number + * - 0-1008: device + */ +#define USERHASH (16) +#define FILEHASH (997) +#define DEVHASH (1009) + +#define DEVSEED (7919) + +static unsigned int dev_hash_value; + +static int set_magic_time(unsigned int user, unsigned int file, unsigned int device) +{ + unsigned int n = user + USERHASH*(file + FILEHASH*device); + + // June 7th, 2006 + static struct rtc_time time = { + .tm_sec = 0, + .tm_min = 0, + .tm_hour = 0, + .tm_mday = 7, + .tm_mon = 5, // June - counting from zero + .tm_year = 106, + .tm_wday = 3, + .tm_yday = 160, + .tm_isdst = 1 + }; + + time.tm_year = (n % 100); + n /= 100; + time.tm_mon = (n % 12); + n /= 12; + time.tm_mday = (n % 28) + 1; + n /= 28; + time.tm_hour = (n % 24); + n /= 24; + time.tm_min = (n % 20) * 3; + n /= 20; + set_rtc_time(&time); + return n ? -1 : 0; +} + +static unsigned int read_magic_time(void) +{ + struct rtc_time time; + unsigned int val; + + get_rtc_time(&time); + printk("Time: %2d:%02d:%02d Date: %02d/%02d/%02d\n", + time.tm_hour, time.tm_min, time.tm_sec, + time.tm_mon, time.tm_mday, time.tm_year); + val = time.tm_year; /* 100 years */ + if (val > 100) + val -= 100; + val += time.tm_mon * 100; /* 12 months */ + val += (time.tm_mday-1) * 100 * 12; /* 28 month-days */ + val += time.tm_hour * 100 * 12 * 28; /* 24 hours */ + val += (time.tm_min / 3) * 100 * 12 * 28 * 24; /* 20 3-minute intervals */ + return val; +} + +/* + * This is just the sdbm hash function with a user-supplied + * seed and final size parameter. + */ +static unsigned int hash_string(unsigned int seed, const char *data, unsigned int mod) +{ + unsigned char c; + while ((c = *data++) != 0) { + seed = (seed << 16) + (seed << 6) - seed + c; + } + return seed % mod; +} + +void set_trace_device(struct device *dev) +{ + dev_hash_value = hash_string(DEVSEED, dev->bus_id, DEVHASH); +} + +/* + * We could just take the "tracedata" index into the .tracedata + * section instead. Generating a hash of the data gives us a + * chance to work across kernel versions, and perhaps more + * importantly it also gives us valid/invalid check (ie we will + * likely not give totally bogus reports - if the hash matches, + * it's not any guarantee, but it's a high _likelihood_ that + * the match is valid). + */ +void generate_resume_trace(void *tracedata, unsigned int user) +{ + unsigned short lineno = *(unsigned short *)tracedata; + const char *file = *(const char **)(tracedata + 2); + unsigned int user_hash_value, file_hash_value; + + user_hash_value = user % USERHASH; + file_hash_value = hash_string(lineno, file, FILEHASH); + set_magic_time(user_hash_value, file_hash_value, dev_hash_value); +} + +extern char __tracedata_start, __tracedata_end; +static int show_file_hash(unsigned int value) +{ + int match; + char *tracedata; + + match = 0; + for (tracedata = &__tracedata_start ; tracedata < &__tracedata_end ; tracedata += 6) { + unsigned short lineno = *(unsigned short *)tracedata; + const char *file = *(const char **)(tracedata + 2); + unsigned int hash = hash_string(lineno, file, FILEHASH); + if (hash != value) + continue; + printk(" hash matches %s:%u\n", file, lineno); + match++; + } + return match; +} + +static int show_dev_hash(unsigned int value) +{ + int match = 0; + struct list_head * entry = dpm_active.prev; + + while (entry != &dpm_active) { + struct device * dev = to_device(entry); + unsigned int hash = hash_string(DEVSEED, dev->bus_id, DEVHASH); + if (hash == value) { + printk(" hash matches device %s\n", dev->bus_id); + match++; + } + entry = entry->prev; + } + return match; +} + +static unsigned int hash_value_early_read; + +static int early_resume_init(void) +{ + hash_value_early_read = read_magic_time(); + return 0; +} + +static int late_resume_init(void) +{ + unsigned int val = hash_value_early_read; + unsigned int user, file, dev; + + user = val % USERHASH; + val = val / USERHASH; + file = val % FILEHASH; + val = val / FILEHASH; + dev = val /* % DEVHASH */; + + printk(" Magic number: %d:%d:%d\n", user, file, dev); + show_file_hash(file); + show_dev_hash(dev); + return 0; +} + +core_initcall(early_resume_init); +late_initcall(late_resume_init); diff --git a/include/asm-generic/rtc.h b/include/asm-generic/rtc.h index cef08db34ad..4087037a422 100644 --- a/include/asm-generic/rtc.h +++ b/include/asm-generic/rtc.h @@ -114,6 +114,7 @@ static inline unsigned int get_rtc_time(struct rtc_time *time) /* Set the current date and time in the real time clock. */ static inline int set_rtc_time(struct rtc_time *time) { + unsigned long flags; unsigned char mon, day, hrs, min, sec; unsigned char save_control, save_freq_select; unsigned int yrs; @@ -131,7 +132,7 @@ static inline int set_rtc_time(struct rtc_time *time) if (yrs > 255) /* They are unsigned */ return -EINVAL; - spin_lock_irq(&rtc_lock); + spin_lock_irqsave(&rtc_lock, flags); #ifdef CONFIG_MACH_DECSTATION real_yrs = yrs; leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) || @@ -152,7 +153,7 @@ static inline int set_rtc_time(struct rtc_time *time) * whether the chip is in binary mode or not. */ if (yrs > 169) { - spin_unlock_irq(&rtc_lock); + spin_unlock_irqrestore(&rtc_lock, flags); return -EINVAL; } @@ -187,7 +188,7 @@ static inline int set_rtc_time(struct rtc_time *time) CMOS_WRITE(save_control, RTC_CONTROL); CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); - spin_unlock_irq(&rtc_lock); + spin_unlock_irqrestore(&rtc_lock, flags); return 0; } diff --git a/include/linux/resume-trace.h b/include/linux/resume-trace.h new file mode 100644 index 00000000000..a376bd4ade3 --- /dev/null +++ b/include/linux/resume-trace.h @@ -0,0 +1,30 @@ +#ifndef RESUME_TRACE_H +#define RESUME_TRACE_H + +#ifdef CONFIG_PM_TRACE + +struct device; +extern void set_trace_device(struct device *); +extern void generate_resume_trace(void *tracedata, unsigned int user); + +#define TRACE_DEVICE(dev) set_trace_device(dev) +#define TRACE_RESUME(user) do { \ + void *tracedata; \ + asm volatile("movl $1f,%0\n" \ + ".section .tracedata,\"a\"\n" \ + "1:\t.word %c1\n" \ + "\t.long %c2\n" \ + ".previous" \ + :"=r" (tracedata) \ + : "i" (__LINE__), "i" (__FILE__)); \ + generate_resume_trace(tracedata, user); \ +} while (0) + +#else + +#define TRACE_DEVICE(dev) do { } while (0) +#define TRACE_RESUME(dev) do { } while (0) + +#endif + +#endif diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index ce0dfb8f4a4..cdf315e794f 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -36,6 +36,15 @@ config PM_DEBUG code. This is helpful when debugging and reporting various PM bugs, like suspend support. +config PM_TRACE + bool "Suspend/resume event tracing" + depends on PM && PM_DEBUG && X86 + default y + ---help--- + This enables some cheesy code to save the last PM event point in the + RTC across reboots, so that you can debug a machine that just hangs + during suspend (or more commonly, during resume). + config SOFTWARE_SUSPEND bool "Software Suspend" depends on PM && SWAP && (X86 && (!SMP || SUSPEND_SMP)) || ((FRV || PPC32) && !SMP) |