projects / people / pmueller / ipfire-2.x.git / blame
| Commit | Line | Data |
|---|---|---|
| 2cb7cef9 BS |
1 | Subject: [PATCH] add syslog printing to xmon debugger. |
| 2 | From: Linas Vepstas <linas@austin.ibm.com> | |
| 3 | ||
| 4 | ||
| 5 | This patch 'dmesg'/printk log buffer printing to xmon. I find this | |
| 6 | useful because crashes are almost always preceeded by interesting | |
| 7 | printk's. This patch is simple & straightforward, except for one | |
| 8 | possibly controversial aspect: it embeds a small snippet in | |
| 9 | kernel/printk.c to return the location of the syslog. This is | |
| 10 | needed because kallsyms and even CONFIG_KALLSYMS_ALL is not enough | |
| 11 | to reveal the location of log_buf. This code is about 90% | |
| 12 | cut-n-paste of earlier code from Keith Owens. | |
| 13 | ||
| 14 | Signed-off-by: Olaf Hering <olh@suse.de> | |
| 15 | ||
| 16 | arch/powerpc/xmon/xmon.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++ | |
| 17 | kernel/printk.c | 15 ++++++++++++ | |
| 18 | 2 files changed, 72 insertions(+) | |
| 19 | ||
| 20 | --- a/arch/powerpc/xmon/xmon.c | |
| 21 | +++ b/arch/powerpc/xmon/xmon.c | |
| 22 | @@ -136,6 +136,7 @@ static struct bpt *in_breakpoint_table(u | |
| 23 | static int do_step(struct pt_regs *); | |
| 24 | static void bpt_cmds(void); | |
| 25 | static void cacheflush(void); | |
| 26 | +static void xmon_show_dmesg(void); | |
| 27 | static int cpu_cmd(void); | |
| 28 | static void csum(void); | |
| 29 | static void bootcmds(void); | |
| 30 | @@ -194,6 +195,7 @@ Commands:\n\ | |
| 31 | #endif | |
| 32 | "\ | |
| 33 | C checksum\n\ | |
| 34 | + D show dmesg (printk) buffer\n\ | |
| 35 | d dump bytes\n\ | |
| 36 | di dump instructions\n\ | |
| 37 | df dump float values\n\ | |
| 38 | @@ -808,6 +810,9 @@ cmds(struct pt_regs *excp) | |
| 39 | case 'd': | |
| 40 | dump(); | |
| 41 | break; | |
| 42 | + case 'D': | |
| 43 | + xmon_show_dmesg(); | |
| 44 | + break; | |
| 45 | case 'l': | |
| 46 | symbol_lookup(); | |
| 47 | break; | |
| 48 | @@ -2522,6 +2527,58 @@ static void xmon_print_symbol(unsigned l | |
| 49 | printf("%s", after); | |
| 50 | } | |
| 51 | ||
| 52 | +extern void debugger_syslog_data(char *syslog_data[4]); | |
| 53 | +#define SYSLOG_WRAP(p) if (p < syslog_data[0]) p = syslog_data[1]-1; \ | |
| 54 | + else if (p >= syslog_data[1]) p = syslog_data[0]; | |
| 55 | + | |
| 56 | +static void xmon_show_dmesg(void) | |
| 57 | +{ | |
| 58 | + char *syslog_data[4], *start, *end, c; | |
| 59 | + int logsize; | |
| 60 | + | |
| 61 | + /* syslog_data[0,1] physical start, end+1. | |
| 62 | + * syslog_data[2,3] logical start, end+1. | |
| 63 | + */ | |
| 64 | + debugger_syslog_data(syslog_data); | |
| 65 | + if (syslog_data[2] == syslog_data[3]) | |
| 66 | + return; | |
| 67 | + logsize = syslog_data[1] - syslog_data[0]; | |
| 68 | + start = syslog_data[0] + (syslog_data[2] - syslog_data[0]) % logsize; | |
| 69 | + end = syslog_data[0] + (syslog_data[3] - syslog_data[0]) % logsize; | |
| 70 | + | |
| 71 | + /* Do a line at a time (max 200 chars) to reduce overhead */ | |
| 72 | + c = '\0'; | |
| 73 | + while(1) { | |
| 74 | + char *p; | |
| 75 | + int chars = 0; | |
| 76 | + if (!*start) { | |
| 77 | + while (!*start) { | |
| 78 | + ++start; | |
| 79 | + SYSLOG_WRAP(start); | |
| 80 | + if (start == end) | |
| 81 | + break; | |
| 82 | + } | |
| 83 | + if (start == end) | |
| 84 | + break; | |
| 85 | + } | |
| 86 | + p = start; | |
| 87 | + while (*start && chars < 200) { | |
| 88 | + c = *start; | |
| 89 | + ++chars; | |
| 90 | + ++start; | |
| 91 | + SYSLOG_WRAP(start); | |
| 92 | + if (start == end || c == '\n') | |
| 93 | + break; | |
| 94 | + } | |
| 95 | + if (chars) | |
| 96 | + printf("%.*s", chars, p); | |
| 97 | + if (start == end) | |
| 98 | + break; | |
| 99 | + } | |
| 100 | + if (c != '\n') | |
| 101 | + printf("\n"); | |
| 102 | +} | |
| 103 | + | |
| 104 | #ifdef CONFIG_PPC64 | |
| 105 | static void dump_slb(void) | |
| 106 | { | |
| 107 | --- a/kernel/printk.c | |
| 108 | +++ b/kernel/printk.c | |
| 109 | @@ -426,6 +426,21 @@ asmlinkage long sys_syslog(int type, cha | |
| 110 | return do_syslog(type, buf, len); | |
| 111 | } | |
| 112 | ||
| 113 | +#ifdef CONFIG_DEBUG_KERNEL | |
| 114 | +/* Its very handy to be able to view the syslog buffer during debug. | |
| 115 | + * But do_syslog() uses locks so it cannot be used during debugging. | |
| 116 | + * Instead, provide the start and end of the physical and logical logs. | |
| 117 | + * This is equivalent to do_syslog(3). | |
| 118 | + */ | |
| 119 | +void debugger_syslog_data(char *syslog_data[4]) | |
| 120 | +{ | |
| 121 | + syslog_data[0] = log_buf; | |
| 122 | + syslog_data[1] = log_buf + log_buf_len; | |
| 123 | + syslog_data[2] = log_buf + log_end - (logged_chars < log_buf_len ? logged_chars : log_buf_len); | |
| 124 | + syslog_data[3] = log_buf + log_end; | |
| 125 | +} | |
| 126 | +#endif /* CONFIG_DEBUG_KERNEL */ | |
| 127 | + | |
| 128 | /* | |
| 129 | * Call the console drivers on a range of log_buf | |
| 130 | */ |