The ftrace log size is configurable via ramoops.ftrace_size module option, and the log itself is available via <pstore-mount>/ftrace-ramoops file.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- Documentation/ramoops.txt | 25 +++++++++++++++++++++++++ fs/pstore/ram.c | 37 +++++++++++++++++++++++++++++++++---- include/linux/pstore_ram.h | 1 + 3 files changed, 59 insertions(+), 4 deletions(-)
diff --git a/Documentation/ramoops.txt b/Documentation/ramoops.txt index 59a74a8..197ad59 100644 --- a/Documentation/ramoops.txt +++ b/Documentation/ramoops.txt @@ -94,3 +94,28 @@ timestamp and a new line. The dump then continues with the actual data. The dump data can be read from the pstore filesystem. The format for these files is "dmesg-ramoops-N", where N is the record number in memory. To delete a stored record from RAM, simply unlink the respective pstore file. + +5. Persistent function tracing + +Persistent function tracing might be useful for debugging software or hardware +related hangs. The functions call chain log is stored in a "ftrace-ramoops" +file. Here is an example of usage: + + # mount -t debugfs debugfs /sys/kernel/debug/ + # cd /sys/kernel/debug/tracing + # echo function > current_tracer + # echo 1 > options/func_pstore + # reboot -f + [...] + # mount -t pstore pstore /mnt/ + # tail /mnt/ftrace-ramoops + 0 ffffffff8101ea64 ffffffff8101bcda native_apic_mem_read <- disconnect_bsp_APIC+0x6a/0xc0 + 0 ffffffff8101ea44 ffffffff8101bcf6 native_apic_mem_write <- disconnect_bsp_APIC+0x86/0xc0 + 0 ffffffff81020084 ffffffff8101a4b5 hpet_disable <- native_machine_shutdown+0x75/0x90 + 0 ffffffff81005f94 ffffffff8101a4bb iommu_shutdown_noop <- native_machine_shutdown+0x7b/0x90 + 0 ffffffff8101a6a1 ffffffff8101a437 native_machine_emergency_restart <- native_machine_restart+0x37/0x40 + 0 ffffffff811f9876 ffffffff8101a73a acpi_reboot <- native_machine_emergency_restart+0xaa/0x1e0 + 0 ffffffff8101a514 ffffffff8101a772 mach_reboot_fixups <- native_machine_emergency_restart+0xe2/0x1e0 + 0 ffffffff811d9c54 ffffffff8101a7a0 __const_udelay <- native_machine_emergency_restart+0x110/0x1e0 + 0 ffffffff811d9c34 ffffffff811d9c80 __delay <- __const_udelay+0x30/0x40 + 0 ffffffff811d9d14 ffffffff811d9c3f delay_tsc <- __delay+0xf/0x20 diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index ee58344..2cc029f 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -45,6 +45,10 @@ static ulong ramoops_console_size = MIN_MEM_SIZE; module_param_named(console_size, ramoops_console_size, ulong, 0400); MODULE_PARM_DESC(console_size, "size of kernel console log");
+static ulong ramoops_ftrace_size = MIN_MEM_SIZE; +module_param_named(ftrace_size, ramoops_ftrace_size, ulong, 0400); +MODULE_PARM_DESC(ftrace_size, "size of ftrace log"); + static ulong mem_address; module_param(mem_address, ulong, 0400); MODULE_PARM_DESC(mem_address, @@ -68,16 +72,19 @@ MODULE_PARM_DESC(ramoops_ecc, struct ramoops_context { struct persistent_ram_zone **przs; struct persistent_ram_zone *cprz; + struct persistent_ram_zone *fprz; phys_addr_t phys_addr; unsigned long size; size_t record_size; size_t console_size; + size_t ftrace_size; int dump_oops; int ecc_size; unsigned int max_dump_cnt; unsigned int dump_write_cnt; unsigned int dump_read_cnt; unsigned int console_read_cnt; + unsigned int ftrace_read_cnt; struct pstore_info pstore; };
@@ -136,6 +143,9 @@ static ssize_t ramoops_pstore_read(u64 *id, enum pstore_type_id *type, prz = ramoops_get_next_prz(&cxt->cprz, &cxt->console_read_cnt, 1, id, type, PSTORE_TYPE_CONSOLE, 0); if (!prz) + prz = ramoops_get_next_prz(&cxt->fprz, &cxt->ftrace_read_cnt, + 1, id, type, PSTORE_TYPE_FTRACE, 0); + if (!prz) return 0;
/* TODO(kees): Bogus time for the moment. */ @@ -184,6 +194,11 @@ static int ramoops_pstore_write_buf(enum pstore_type_id type, return -ENOMEM; persistent_ram_write(cxt->cprz, buf, size); return 0; + } else if (type == PSTORE_TYPE_FTRACE) { + if (!cxt->fprz) + return -ENOMEM; + persistent_ram_write(cxt->fprz, buf, size); + return 0; }
if (type != PSTORE_TYPE_DMESG) @@ -233,6 +248,9 @@ static int ramoops_pstore_erase(enum pstore_type_id type, u64 id, case PSTORE_TYPE_CONSOLE: prz = cxt->cprz; break; + case PSTORE_TYPE_FTRACE: + prz = cxt->fprz; + break; default: return -EINVAL; } @@ -346,7 +364,8 @@ static int __devinit ramoops_probe(struct platform_device *pdev) if (cxt->max_dump_cnt) goto fail_out;
- if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size)) { + if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size && + !pdata->ftrace_size)) { pr_err("The memory size and the record/console size must be " "non-zero\n"); goto fail_out; @@ -355,18 +374,20 @@ static int __devinit ramoops_probe(struct platform_device *pdev) pdata->mem_size = rounddown_pow_of_two(pdata->mem_size); pdata->record_size = rounddown_pow_of_two(pdata->record_size); pdata->console_size = rounddown_pow_of_two(pdata->console_size); + pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
cxt->dump_read_cnt = 0; cxt->size = pdata->mem_size; cxt->phys_addr = pdata->mem_address; cxt->record_size = pdata->record_size; cxt->console_size = pdata->console_size; + cxt->ftrace_size = pdata->ftrace_size; cxt->dump_oops = pdata->dump_oops; cxt->ecc_size = pdata->ecc_size;
paddr = cxt->phys_addr;
- dump_mem_sz = cxt->size - cxt->console_size; + dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size; err = ramoops_init_przs(dev, cxt, &paddr, dump_mem_sz); if (err) goto fail_out; @@ -375,9 +396,14 @@ static int __devinit ramoops_probe(struct platform_device *pdev) if (err) goto fail_init_cprz;
- if (!cxt->przs && !cxt->cprz) { + err = ramoops_init_prz(dev, cxt, &cxt->fprz, &paddr, cxt->ftrace_size); + if (err) + goto fail_init_fprz; + + if (!cxt->przs && !cxt->cprz && !cxt->fprz) { pr_err("memory size too small, minimum is %lu\n", - cxt->console_size + cxt->record_size); + cxt->console_size + cxt->record_size + + cxt->ftrace_size); goto fail_cnt; }
@@ -424,6 +450,8 @@ fail_clear: cxt->pstore.bufsize = 0; cxt->max_dump_cnt = 0; fail_cnt: + kfree(cxt->fprz); +fail_init_fprz: kfree(cxt->cprz); fail_init_cprz: ramoops_free_przs(cxt); @@ -478,6 +506,7 @@ static void ramoops_register_dummy(void) dummy_data->mem_address = mem_address; dummy_data->record_size = record_size; dummy_data->console_size = ramoops_console_size; + dummy_data->ftrace_size = ramoops_ftrace_size; dummy_data->dump_oops = dump_oops; dummy_data->ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;
diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h index dcf805f..af848e1 100644 --- a/include/linux/pstore_ram.h +++ b/include/linux/pstore_ram.h @@ -72,6 +72,7 @@ struct ramoops_platform_data { unsigned long mem_address; unsigned long record_size; unsigned long console_size; + unsigned long ftrace_size; int dump_oops; int ecc_size; };