powerpc/powernv: Add debugfs file to grab opalv3 trace data
PATCH 1/1 powerpc/powernv: Add debugfs file to grab opalv3 trace data
This adds files in debugfs that can be used to retrieve the OPALv3 firmware "live binary traces" which can then be parsed using a userspace tool.
Mostly from Rusty with some updates by myself (BenH)
---
Reworked from whatever ancient version has been rotting in patchwork, this one is updated to the actual properties exposed by skiboot nowadays, endian fixed, and has the ability to set the trace mask.
arch/powerpc/platforms/powernv/Makefile | 2 +- arch/powerpc/platforms/powernv/opal-trace-types.h | 58 +++++++ arch/powerpc/platforms/powernv/opal-trace.c | 202 ++++++++++++++++++++++ 3 files changed, 261 insertions(+), 1 deletion(-) create mode 100644 arch/powerpc/platforms/powernv/opal-trace-types.h create mode 100644 arch/powerpc/platforms/powernv/opal-trace.c
arch/powerpc/platforms/powernv/Makefile +1 -1
@@ -1,7 +1,7 @@ obj-y += setup.o opal-wrappers.o opal.o opal-async.o obj-y += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o obj-y += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o -obj-y += opal-msglog.o opal-hmi.o +obj-y += opal-msglog.o opal-hmi.o opal-trace.o obj-$(CONFIG_SMP) += smp.o subcore.o subcore-asm.o obj-$(CONFIG_PCI) += pci.o pci-p5ioc2.o pci-ioda.o
arch/powerpc/platforms/powernv/opal-trace-types.h new file +58 -0
58 lines not on this page · raw message
arch/powerpc/platforms/powernv/opal-trace.c new file +202 -0
202 lines not on this page · raw message
Michael Ellerman
reviewerQuoted 8 lines · Benjamin Herrenschmidt
This adds files in debugfs that can be used to retrieve the OPALv3 firmware "live binary traces" which can then be parsed using a userspace tool.
Mostly from Rusty with some updates by myself (BenH)
Signed-off-by Rusty Russell <[email protected]>Signed-off-by Benjamin Herrenschmidt <[email protected]>
Conspicuous review of patch from maintainer follows ...
Meta-comment: given we need a userspace tool to read the trace anyway, could we make this a lot simpler by just letting userspace mmap the trace buffers?
arch/powerpc/platforms/powernv/Makefile line 4
Quoted 10 lines
arch/powerpc/platforms/powernv/Makefile +1
-1@@ -1,7 +1,7 @@ obj-y += setup.o opal-wrappers.o opal.o opal-async.o obj-y += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o obj-y += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o -obj-y += opal-msglog.o opal-hmi.o +obj-y += opal-msglog.o opal-hmi.o opal-trace.o
Should depend on CONFIG_DEBUG_FS at least no?
arch/powerpc/platforms/powernv/opal-trace-types.h line 1
Quoted 7 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +1
-0@@ -0,0 +1,58 @@ +/* API for kernel to read trace buffer. */
Copyright/GPL header ?
/*
* Copyright 201x, Purple Monkey Dishwasher, IBM Corporation. *
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version. */
arch/powerpc/platforms/powernv/opal-trace-types.h line 3
Quoted 2 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +2
-0+#ifndef __OPAL_TRACE_TYPES_H +#define __OPAL_TRACE_TYPES_H
We usually do __POWERNV_FOO_H for these. But they're all a bit of a mess.
arch/powerpc/platforms/powernv/opal-trace-types.h line 8
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+#define TRACE_REPEAT 1 +#define TRACE_OVERFLOW 2 +#define TRACE_OPAL 3 +#define TRACE_FSP 4
Linux tracepoints defines a bunch of TRACE_FOO macros, obviously REPEAT is the only one that's likely to clash. But still might be worth namespacing.
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+/* One per cpu, plus one for NMIs */ +struct tracebuf { +/* Mask to apply to get buffer offset. */ +__be64 mask;
arch/powerpc/platforms/powernv/opal-trace-types.h line 23
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +10
-0+/* This where the buffer starts. */ +__be64 start; +/* This is where writer has written to. */ +__be64 end; +/* This is where the writer wrote to previously. */ +__be64 last; +/* This is where the reader is up to. */ +__be64 rpos; +/* If the last one we read was a repeat, this shows how many. */ +__be32 last_repeat;
So I think start/end/last/rpos/last_repeat are all full virtual addresses right?
arch/powerpc/platforms/powernv/opal-trace-types.h line 27
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+/* Maximum possible size of a record. */ +__be32 max_size; + +char buf[/* TBUF_SZ + max_size */ ];
We don't have TBUF_SZ.
arch/powerpc/platforms/powernv/opal-trace-types.h line 38
Quoted 11 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +11
-0+}; + +/* Common header for all trace entries. */ +struct trace_hdr { +__be64 timestamp; +u8 type; +u8 len_div_8; +__be16 cpu; +u8 unused[4 ]; +}; +
The comment below is attached to trace_repeat, but it seems like it should go with hdr no ?
Quoted 8 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +8
-0+/* Note: all other entries must be at least as large as this! */ +struct trace_repeat { +__be64 timestamp;/* Last repeat happened at this timestamp */ +u8 type;/* == TRACE_REPEAT */ +u8 len_div_8; +__be16 cpu; +__be16 prev_len; +__be16 num;/* Starts at 1, ie. 1 repeat, or two traces. */
arch/powerpc/platforms/powernv/opal-trace-types.h line 56
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +10
-0+/* Note that the count can be one short, if read races a repeat. */ +}; + +struct trace_overflow { +__be64 unused64;/* Timestamp is unused */ +u8 type;/* == TRACE_OVERFLOW */ +u8 len_div_8; +u8 unused[6 ];/* ie. hdr.cpu is indeterminate */ +__be64 bytes_missed; +};
Some lining up of comments would help readability of those.
arch/powerpc/platforms/powernv/opal-trace.c line 3
Quoted 9 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +3
-0@@ -0,0 +1,202 @@ +/* +* Copyright (C) 2013 Rusty Russell, IBM Corporation +*
GPL ?
arch/powerpc/platforms/powernv/opal-trace.c line 4
Quoted 1 line
arch/powerpc/platforms/powernv/opal-trace.c new file +1
-0+* Simple debugfs file firmware_trace to read out OPALv3 trace
^
now called opal-trace
arch/powerpc/platforms/powernv/opal-trace.c line 6
Quoted 2 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +2
-0+* ringbuffers. +*/
<blank>
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +4
-0+#include <linux/mutex.h> +#include <linux/debugfs.h> +#include <linux/uaccess.h> +#include <linux/of.h>
arch/powerpc/platforms/powernv/opal-trace.c line 20
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+#include <linux/slab.h> +#include <asm/debug.h> +#include <asm/opal.h> + +#include "opal-trace-types.h" + +static DEFINE_MUTEX (tracelock); +static struct tracebuf **opal_tb; +static size_t opal_num_tb; +static __be64 *opal_tmask_p;
_p ? pointer, or phys?
arch/powerpc/platforms/powernv/opal-trace.c line 29
Quoted 9 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +9
-0+ +/* Maximum possible size of record (since len is 8 bits). */ +union max_trace { +struct trace_hdr hdr; +struct trace_overflow overflow; +struct trace_repeat repeat; +char buf[255 *8 ]; +}; +static union max_trace trace;
I *think* this is only used in opal_trace_read(), so it'd be nice if it was in there.
Quoted 27 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +27
-0+static bool trace_empty (const struct tracebuf *tb) +{ +const struct trace_repeat *rep; + +if (tb->rpos == tb->end) +return true; + +/* +* If we have a single element only, and it's a repeat buffer +* we've already seen every repeat for (yet which may be +* incremented in future), we're also empty. +*/ + rep = (void *)tb->buf + (be64_to_cpu (tb->rpos & tb->mask)); +if (be64_to_cpu (tb->end) !=be64_to_cpu (tb->rpos) +sizeof (*rep)) +return false; + +if (rep->type !=TRACE_REPEAT ) +return false; + +if (be16_to_cpu (rep->num) !=be32_to_cpu (tb->last_repeat)) +return false; + +return true; +} + +/* You can't read in parallel, so some locking required in caller. */ +static bool trace_get (union max_trace *t,struct tracebuf *tb)
arch/powerpc/platforms/powernv/opal-trace.c line 67
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+{ +u64 start, rpos; + +if (trace_empty (tb)) +return false; + +again: +/* +* The actual buffer is slightly larger than tbsize, so this +* memcpy is always valid.
We don't seem to have tbsize anymore?
Quoted 27 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +27
-0+*/ +memcpy (t, tb->buf +be64_to_cpu (tb->rpos & tb->mask), +be32_to_cpu (tb->max_size)); + +rmb ();/* read barrier, so we read tb->start after copying record. */ + + start =be64_to_cpu (tb->start); + rpos =be64_to_cpu (tb->rpos); + +/* Now, was that overwritten? */ +if (rpos < start) { +/* Create overflow record. */ + t->overflow.unused64 =0 ; + t->overflow.type =TRACE_OVERFLOW ; + t->overflow.len_div_8 =sizeof (t->overflow) /8 ; + t->overflow.bytes_missed =cpu_to_be64 (start - rpos); + tb->rpos =cpu_to_be64 (start); +return true; + } + +/* Repeat entries need special handling */ +if (t->hdr.type ==TRACE_REPEAT ) { +u32 num =be16_to_cpu (t->repeat.num); + +/* In case we've read some already... */ + t->repeat.num =cpu_to_be16 (num -be32_to_cpu (tb->last_repeat)); +
arch/powerpc/platforms/powernv/opal-trace.c line 104
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+/* Record how many repeats we saw this time. */ + tb->last_repeat =cpu_to_be32 (num); + +/* Don't report an empty repeat buffer. */ +if (t->repeat.num ==0 ) { +/* +* This can't be the last buffer, otherwise +* trace_empty would have returned true. +*/ +BUG_ON (be64_to_cpu (tb->end) <= rpos + t->hdr.len_div_8 *8 );
Can we just WARN_ON() and bail, seeing as this is for debug. I'd hate to panic a customer system by dumping the trace buffer.
Quoted 14 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +14
-0+/* Skip to next entry. */ + tb->rpos =cpu_to_be64 (rpos + t->hdr.len_div_8 *8 ); + goto again; + } + }else { + tb->last_repeat =0 ; + tb->rpos =cpu_to_be64 (rpos + t->hdr.len_div_8 *8 ); + } + +return true; +} + +/* Horrible polling interface, designed for dumping. */ +static ssize_t opal_trace_read(struct file *file, char __user *ubuf,
arch/powerpc/platforms/powernv/opal-trace.c line 128
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+ size_t count, loff_t *ppos) +{ + ssize_t err; +unsigned int i; + + err =mutex_lock_interruptible (&tracelock); +if (err) +return err; + +for (i =0 ; i < opal_num_tb; i++) {
OK so I understand this now. You have multiple trace buffers, but you don't care about maintaining that separation. You just merge all the streams here into a single output stream.
Quoted 23 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +23
-0+if (trace_get (&trace, opal_tb[i])) { +size_t len = trace.hdr.len_div_8 *8 ; +if (len > count) + len = count; +if (copy_to_user (ubuf, &trace, len) !=0 ) + err = -EFAULT ; +else + err = len; +break ; + } + } + +mutex_unlock (&tracelock); +return err; +} + +static const struct file_operations opal_trace_fops = { + .read = opal_trace_read, + .open = simple_open, + .llseek = noop_llseek, +}; + +static int opal_tmask_set (void *data,u64 val)
arch/powerpc/platforms/powernv/opal-trace.c line 161
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+{ + *(__be64 *)data =cpu_to_be64 (val); +return 0 ; +} +static int opal_tmask_get (void *data,u64 *val) +{ + *val =be64_to_cpup ((__be64 *)data); +return 0 ; +} +DEFINE_SIMPLE_ATTRIBUTE (opal_tmask, opal_tmask_get, opal_tmask_set,"%llx\n" );
What is a tmask ?
I assume it's some mask of things we want traced?
Quoted 7 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+static int opal_trace_init (void ) +{ +const __be64 *traces; +int len, i, rc; +u64 tmask_phys; + +if (!opal_node)
arch/powerpc/platforms/powernv/opal-trace.c line 179
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+return -ENODEV ; + + traces =of_get_property (opal_node,"ibm,opal-traces" , &len); +if (!traces) { +pr_warning ("%s: OPAL node property \"ibm,opal-traces\"" +" not found\n" , __func__); +return -ENODEV ; + } + + opal_num_tb = len / (sizeof (__be64) *2 );
So I won't say the "b" word, but it'd be nice to have at least a comment on what the device tree property contains.
arch/powerpc/platforms/powernv/opal-trace.c line 187
Quoted 8 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +8
-0+if (!opal_num_tb) { +pr_warning ("%s: OPAL traces property has invalid length %i\n" , + __func__, len); +return -EINVAL ; + } + opal_tb =kmalloc (sizeof (*opal_tb) * opal_num_tb,GFP_KERNEL ); +for (i =0 ; i < opal_num_tb; i++) + opal_tb[i] =__va (be64_to_cpu (traces[i*2 ]));
Just __va() ? ie. it's already in the linear mapping somewhere?
arch/powerpc/platforms/powernv/opal-trace.c line 195
Quoted 7 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+debugfs_create_file ("opal-trace" ,S_IRUSR , powerpc_debugfs_root, +NULL , &opal_trace_fops); + rc =of_property_read_u64 (opal_node,"ibm,opal-trace-mask" , + &tmask_phys); +if (!rc) + opal_tmask_p =__va (tmask_phys); +if (opal_tmask_p)
If tmask_phys was 0, opal_tmask_p is now 0xc00..00, so is that what we want to check?
arch/powerpc/platforms/powernv/opal-trace.c line 202
Quoted 7 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+debugfs_create_file ("opal-trace-mask" ,S_IRUSR |S_IWUSR , + powerpc_debugfs_root, opal_tmask_p, + &opal_tmask); +return 0 ; +} +module_init (opal_trace_init); +
cheers
Quoted 60 lines · Michael Ellerman
Quoted 8 lines · Benjamin Herrenschmidt
This adds files in debugfs that can be used to retrieve the OPALv3 firmware "live binary traces" which can then be parsed using a userspace tool.
Mostly from Rusty with some updates by myself (BenH)
Signed-off-by Rusty Russell <[email protected]>Signed-off-by Benjamin Herrenschmidt <[email protected]>Conspicuous review of patch from maintainer follows ...
Meta-comment: given we need a userspace tool to read the trace anyway, could we make this a lot simpler by just letting userspace mmap the trace buffers?
arch/powerpc/platforms/powernv/Makefile line 4
Quoted 10 lines
arch/powerpc/platforms/powernv/Makefile +1
-1@@ -1,7 +1,7 @@ obj-y += setup.o opal-wrappers.o opal.o opal-async.o obj-y += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o obj-y += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o -obj-y += opal-msglog.o opal-hmi.o +obj-y += opal-msglog.o opal-hmi.o opal-trace.oShould depend on
CONFIG_DEBUG_FSat least no?arch/powerpc/platforms/powernv/opal-trace-types.h line 1
Quoted 7 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +1
-0@@ -0,0 +1,58 @@ +/* API for kernel to read trace buffer. */ Copyright/GPL header ?
/*
* Copyright 201x, Purple Monkey Dishwasher, IBM Corporation. *
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version. */arch/powerpc/platforms/powernv/opal-trace-types.h line 3
Quoted 2 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +2
-0+#ifndef __OPAL_TRACE_TYPES_H +#define __OPAL_TRACE_TYPES_HWe usually do
__POWERNV_FOO_Hfor these. But they're all a bit of a mess.arch/powerpc/platforms/powernv/opal-trace-types.h line 8
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+#define TRACE_REPEAT 1 +#define TRACE_OVERFLOW 2 +#define TRACE_OPAL 3 +#define TRACE_FSP 4Linux tracepoints defines a bunch of
TRACE_FOOmacros, obviously REPEAT is the only one that's likely to clash. But still might be worth namespacing.
Quoted 16 lines
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+/* One per cpu, plus one for NMIs */ +struct tracebuf { +/* Mask to apply to get buffer offset. */ +__be64 mask;arch/powerpc/platforms/powernv/opal-trace-types.h line 23
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +10
-0+/* This where the buffer starts. */ +__be64 start; +/* This is where writer has written to. */ +__be64 end; +/* This is where the writer wrote to previously. */ +__be64 last; +/* This is where the reader is up to. */ +__be64 rpos; +/* If the last one we read was a repeat, this shows how many. */ +__be32 last_repeat;So I think start/end/last/rpos/last_repeat are all full virtual addresses right?
No, offsets. I'll let Rusty comment on the rest :)
Quoted 292 lines
arch/powerpc/platforms/powernv/opal-trace-types.h line 27
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+/* Maximum possible size of a record. */ +__be32 max_size; + +char buf[/* TBUF_SZ + max_size */ ];We don't have
TBUF_SZ.arch/powerpc/platforms/powernv/opal-trace-types.h line 38
Quoted 11 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +11
-0+}; + +/* Common header for all trace entries. */ +struct trace_hdr { +__be64 timestamp; +u8 type; +u8 len_div_8; +__be16 cpu; +u8 unused[4 ]; +}; +The comment below is attached to
trace_repeat, but it seems like it should go with hdr no ?Quoted 8 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +8
-0+/* Note: all other entries must be at least as large as this! */ +struct trace_repeat { +__be64 timestamp;/* Last repeat happened at this timestamp */ +u8 type;/* == TRACE_REPEAT */ +u8 len_div_8; +__be16 cpu; +__be16 prev_len; +__be16 num;/* Starts at 1, ie. 1 repeat, or two traces. */ arch/powerpc/platforms/powernv/opal-trace-types.h line 56
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace-types.h new file +10
-0+/* Note that the count can be one short, if read races a repeat. */ +}; + +struct trace_overflow { +__be64 unused64;/* Timestamp is unused */ +u8 type;/* == TRACE_OVERFLOW */ +u8 len_div_8; +u8 unused[6 ];/* ie. hdr.cpu is indeterminate */ +__be64 bytes_missed; +};Some lining up of comments would help readability of those.
arch/powerpc/platforms/powernv/opal-trace.c line 3
Quoted 9 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +3
-0@@ -0,0 +1,202 @@ +/* +* Copyright (C) 2013 Rusty Russell, IBM Corporation +* GPL ?
arch/powerpc/platforms/powernv/opal-trace.c line 4
Quoted 1 line
arch/powerpc/platforms/powernv/opal-trace.c new file +1
-0+* Simple debugfs file firmware_trace to read out OPALv3 trace ^
now called opal-tracearch/powerpc/platforms/powernv/opal-trace.c line 6
Quoted 2 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +2
-0+* ringbuffers. +*/ <blank>
Quoted 4 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +4
-0+#include <linux/mutex.h> +#include <linux/debugfs.h> +#include <linux/uaccess.h> +#include <linux/of.h> arch/powerpc/platforms/powernv/opal-trace.c line 20
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+#include <linux/slab.h> +#include <asm/debug.h> +#include <asm/opal.h> + +#include "opal-trace-types.h" + +static DEFINE_MUTEX (tracelock); +static struct tracebuf **opal_tb; +static size_t opal_num_tb; +static __be64 *opal_tmask_p;_p ? pointer, or phys?
arch/powerpc/platforms/powernv/opal-trace.c line 29
Quoted 9 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +9
-0+ +/* Maximum possible size of record (since len is 8 bits). */ +union max_trace { +struct trace_hdr hdr; +struct trace_overflow overflow; +struct trace_repeat repeat; +char buf[255 *8 ]; +}; +static union max_trace trace;I *think* this is only used in
opal_trace_read(), so it'd be nice if it was in there.Quoted 27 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +27
-0+static bool trace_empty (const struct tracebuf *tb) +{ +const struct trace_repeat *rep; + +if (tb->rpos == tb->end) +return true; + +/* +* If we have a single element only, and it's a repeat buffer +* we've already seen every repeat for (yet which may be +* incremented in future), we're also empty. +*/ + rep = (void *)tb->buf + (be64_to_cpu (tb->rpos & tb->mask)); +if (be64_to_cpu (tb->end) !=be64_to_cpu (tb->rpos) +sizeof (*rep)) +return false; + +if (rep->type !=TRACE_REPEAT ) +return false; + +if (be16_to_cpu (rep->num) !=be32_to_cpu (tb->last_repeat)) +return false; + +return true; +} + +/* You can't read in parallel, so some locking required in caller. */ +static bool trace_get (union max_trace *t,struct tracebuf *tb)arch/powerpc/platforms/powernv/opal-trace.c line 67
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+{ +u64 start, rpos; + +if (trace_empty (tb)) +return false; + +again: +/* +* The actual buffer is slightly larger than tbsize, so this +* memcpy is always valid. We don't seem to have tbsize anymore?
Quoted 27 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +27
-0+*/ +memcpy (t, tb->buf +be64_to_cpu (tb->rpos & tb->mask), +be32_to_cpu (tb->max_size)); + +rmb ();/* read barrier, so we read tb->start after copying record. */ + + start =be64_to_cpu (tb->start); + rpos =be64_to_cpu (tb->rpos); + +/* Now, was that overwritten? */ +if (rpos < start) { +/* Create overflow record. */ + t->overflow.unused64 =0 ; + t->overflow.type =TRACE_OVERFLOW ; + t->overflow.len_div_8 =sizeof (t->overflow) /8 ; + t->overflow.bytes_missed =cpu_to_be64 (start - rpos); + tb->rpos =cpu_to_be64 (start); +return true; + } + +/* Repeat entries need special handling */ +if (t->hdr.type ==TRACE_REPEAT ) { +u32 num =be16_to_cpu (t->repeat.num); + +/* In case we've read some already... */ + t->repeat.num =cpu_to_be16 (num -be32_to_cpu (tb->last_repeat)); +arch/powerpc/platforms/powernv/opal-trace.c line 104
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+/* Record how many repeats we saw this time. */ + tb->last_repeat =cpu_to_be32 (num); + +/* Don't report an empty repeat buffer. */ +if (t->repeat.num ==0 ) { +/* +* This can't be the last buffer, otherwise +* trace_empty would have returned true. +*/ +BUG_ON (be64_to_cpu (tb->end) <= rpos + t->hdr.len_div_8 *8 );Can we just
WARN_ON()and bail, seeing as this is for debug. I'd hate to panic a customer system by dumping the trace buffer.Quoted 14 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +14
-0+/* Skip to next entry. */ + tb->rpos =cpu_to_be64 (rpos + t->hdr.len_div_8 *8 ); + goto again; + } + }else { + tb->last_repeat =0 ; + tb->rpos =cpu_to_be64 (rpos + t->hdr.len_div_8 *8 ); + } + +return true; +} + +/* Horrible polling interface, designed for dumping. */ +static ssize_t opal_trace_read(struct file *file, char __user *ubuf,arch/powerpc/platforms/powernv/opal-trace.c line 128
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+ size_t count, loff_t *ppos) +{ + ssize_t err; +unsigned int i; + + err =mutex_lock_interruptible (&tracelock); +if (err) +return err; + +for (i =0 ; i < opal_num_tb; i++) {OK so I understand this now. You have multiple trace buffers, but you don't care about maintaining that separation. You just merge all the streams here into a single output stream.
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arch/powerpc/platforms/powernv/opal-trace.c new file +23
-0+if (trace_get (&trace, opal_tb[i])) { +size_t len = trace.hdr.len_div_8 *8 ; +if (len > count) + len = count; +if (copy_to_user (ubuf, &trace, len) !=0 ) + err = -EFAULT ; +else + err = len; +break ; + } + } + +mutex_unlock (&tracelock); +return err; +} + +static const struct file_operations opal_trace_fops = { + .read = opal_trace_read, + .open = simple_open, + .llseek = noop_llseek, +}; + +static int opal_tmask_set (void *data,u64 val)arch/powerpc/platforms/powernv/opal-trace.c line 161
Quoted 10 lines
arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+{ + *(__be64 *)data =cpu_to_be64 (val); +return 0 ; +} +static int opal_tmask_get (void *data,u64 *val) +{ + *val =be64_to_cpup ((__be64 *)data); +return 0 ; +} +DEFINE_SIMPLE_ATTRIBUTE (opal_tmask, opal_tmask_get, opal_tmask_set,"%llx\n" );What is a tmask ?
I assume it's some mask of things we want traced?
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arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+static int opal_trace_init (void ) +{ +const __be64 *traces; +int len, i, rc; +u64 tmask_phys; + +if (!opal_node)arch/powerpc/platforms/powernv/opal-trace.c line 179
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arch/powerpc/platforms/powernv/opal-trace.c new file +10
-0+return -ENODEV ; + + traces =of_get_property (opal_node,"ibm,opal-traces" , &len); +if (!traces) { +pr_warning ("%s: OPAL node property \"ibm,opal-traces\"" +" not found\n" , __func__); +return -ENODEV ; + } + + opal_num_tb = len / (sizeof (__be64) *2 );So I won't say the "b" word, but it'd be nice to have at least a comment on what the device tree property contains.
arch/powerpc/platforms/powernv/opal-trace.c line 187
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arch/powerpc/platforms/powernv/opal-trace.c new file +8
-0+if (!opal_num_tb) { +pr_warning ("%s: OPAL traces property has invalid length %i\n" , + __func__, len); +return -EINVAL ; + } + opal_tb =kmalloc (sizeof (*opal_tb) * opal_num_tb,GFP_KERNEL ); +for (i =0 ; i < opal_num_tb; i++) + opal_tb[i] =__va (be64_to_cpu (traces[i*2 ]));Just
__va()? ie. it's already in the linear mapping somewhere?arch/powerpc/platforms/powernv/opal-trace.c line 195
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arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+debugfs_create_file ("opal-trace" ,S_IRUSR , powerpc_debugfs_root, +NULL , &opal_trace_fops); + rc =of_property_read_u64 (opal_node,"ibm,opal-trace-mask" , + &tmask_phys); +if (!rc) + opal_tmask_p =__va (tmask_phys); +if (opal_tmask_p)If
tmask_physwas 0,opal_tmask_pis now 0xc00..00, so is that what we want to check?arch/powerpc/platforms/powernv/opal-trace.c line 202
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arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+debugfs_create_file ("opal-trace-mask" ,S_IRUSR |S_IWUSR , + powerpc_debugfs_root, opal_tmask_p, + &opal_tmask); +return 0 ; +} +module_init (opal_trace_init); +cheers
Quoted 7 lines · Michael Ellerman
Quoted 6 lines · Benjamin Herrenschmidt
This adds files in debugfs that can be used to retrieve the OPALv3 firmware "live binary traces" which can then be parsed using a userspace tool.
Mostly from Rusty with some updates by myself (BenH)
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Signed-off-by Rusty Russell <[email protected]>Signed-off-by Benjamin Herrenschmidt <[email protected]>Conspicuous review of patch from maintainer follows ...
Meta-comment: given we need a userspace tool to read the trace anyway, could we make this a lot simpler by just letting userspace mmap the trace buffers?
We could, but we'd still need a kernel driver to mmap it and in the end, I like being able to ask a user to "cat" the trace into a file, which can then be parsed by the tool offline or on a different machine. It's a nicer interface.
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arch/powerpc/platforms/powernv/Makefile +0
-0
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arch/powerpc/platforms/powernv/Makefile line 4
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arch/powerpc/platforms/powernv/Makefile +1
-1@@ -1,7 +1,7 @@ obj-y += setup.o opal-wrappers.o opal.o opal-async.o obj-y += opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o obj-y += rng.o opal-elog.o opal-dump.o opal-sysparam.o opal-sensor.o -obj-y += opal-msglog.o opal-hmi.o +obj-y += opal-msglog.o opal-hmi.o opal-trace.oShould depend on
CONFIG_DEBUG_FSat least no?
Yes.
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arch/powerpc/platforms/powernv/opal-trace-types.h line 1
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +1
-0@@ -0,0 +1,58 @@ +/* API for kernel to read trace buffer. */ Copyright/GPL header ?
:-)
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/*
* Copyright 201x, Purple Monkey Dishwasher, IBM Corporation. *
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version. */
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arch/powerpc/platforms/powernv/opal-trace-types.h line 3
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +2
-0+#ifndef __OPAL_TRACE_TYPES_H +#define __OPAL_TRACE_TYPES_HWe usually do
__POWERNV_FOO_Hfor these. But they're all a bit of a mess.
Right, that file comes from OPAL and I kept it as-is (well mostly, this is a subset since the kernel doesn't need the definition of the individual trace entries). We could just move the whole lot to the new OPAL API stuff.
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arch/powerpc/platforms/powernv/opal-trace-types.h line 8
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+#define TRACE_REPEAT 1 +#define TRACE_OVERFLOW 2 +#define TRACE_OPAL 3 +#define TRACE_FSP 4Linux tracepoints defines a bunch of
TRACE_FOOmacros, obviously REPEAT is the only one that's likely to clash. But still might be worth namespacing.
Ack.
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +8
-0+/* One per cpu, plus one for NMIs */ +struct tracebuf { +/* Mask to apply to get buffer offset. */ +__be64 mask; +/* This where the buffer starts. */ +__be64 start; +/* This is where writer has written to. */ +__be64 end;
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arch/powerpc/platforms/powernv/opal-trace-types.h line 23
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +6
-0+/* This is where the writer wrote to previously. */ +__be64 last; +/* This is where the reader is up to. */ +__be64 rpos; +/* If the last one we read was a repeat, this shows how many. */ +__be32 last_repeat;So I think start/end/last/rpos/last_repeat are all full virtual addresses right?
Offsets.
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arch/powerpc/platforms/powernv/opal-trace-types.h line 27
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +4
-0+/* Maximum possible size of a record. */ +__be32 max_size; + +char buf[/* TBUF_SZ + max_size */ ];We don't have
TBUF_SZ.
Right, it's just a comment but yes it could be nicer
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +6
-0+}; + +/* Common header for all trace entries. */ +struct trace_hdr { +__be64 timestamp; +u8 type;
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arch/powerpc/platforms/powernv/opal-trace-types.h line 38
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +5
-0+u8 len_div_8; +__be16 cpu; +u8 unused[4 ]; +}; +The comment below is attached to
trace_repeat, but it seems like it should go with hdr no ?Quoted 1 line
arch/powerpc/platforms/powernv/opal-trace-types.h new file +1
-0+/* Note: all other entries must be at least as large as this! */
Well... so all entries should be at least as large as a trace_repeat, which happens to "fit" in the trace_hdr because of the 4 unused...
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +11
-0+struct trace_repeat { +__be64 timestamp;/* Last repeat happened at this timestamp */ +u8 type;/* == TRACE_REPEAT */ +u8 len_div_8; +__be16 cpu; +__be16 prev_len; +__be16 num;/* Starts at 1, ie. 1 repeat, or two traces. */ +/* Note that the count can be one short, if read races a repeat. */ +}; + +struct trace_overflow {
Quoted 8 lines
arch/powerpc/platforms/powernv/opal-trace-types.h line 56
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arch/powerpc/platforms/powernv/opal-trace-types.h new file +6
-0+__be64 unused64;/* Timestamp is unused */ +u8 type;/* == TRACE_OVERFLOW */ +u8 len_div_8; +u8 unused[6 ];/* ie. hdr.cpu is indeterminate */ +__be64 bytes_missed; +};Some lining up of comments would help readability of those.
Ok.
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arch/powerpc/platforms/powernv/opal-trace.c line 3
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arch/powerpc/platforms/powernv/opal-trace.c new file +3
-0@@ -0,0 +1,202 @@ +/* +* Copyright (C) 2013 Rusty Russell, IBM Corporation +* GPL ?
I tend to (incorrectly ?) assume that a .c file in the kernel tree, in absence of other mention, is covered by the top level GPL but it's probably better to make it explicit.
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arch/powerpc/platforms/powernv/opal-trace.c line 4
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arch/powerpc/platforms/powernv/opal-trace.c new file +1
-0+* Simple debugfs file firmware_trace to read out OPALv3 trace ^
now called opal-tracearch/powerpc/platforms/powernv/opal-trace.c line 6
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arch/powerpc/platforms/powernv/opal-trace.c new file +2
-0+* ringbuffers. +*/ <blank>
It's pretty isn't it ? :-)
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arch/powerpc/platforms/powernv/opal-trace.c new file +8
-0+#include <linux/mutex.h> +#include <linux/debugfs.h> +#include <linux/uaccess.h> +#include <linux/of.h> +#include <linux/slab.h> +#include <asm/debug.h> +#include <asm/opal.h> +
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arch/powerpc/platforms/powernv/opal-trace.c line 20
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arch/powerpc/platforms/powernv/opal-trace.c new file +6
-0+#include "opal-trace-types.h" + +static DEFINE_MUTEX (tracelock); +static struct tracebuf **opal_tb; +static size_t opal_num_tb; +static __be64 *opal_tmask_p;_p ? pointer, or phys?
I don't remember, read the code :-)
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arch/powerpc/platforms/powernv/opal-trace.c new file +4
-0+ +/* Maximum possible size of record (since len is 8 bits). */ +union max_trace { +struct trace_hdr hdr;
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arch/powerpc/platforms/powernv/opal-trace.c line 29
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arch/powerpc/platforms/powernv/opal-trace.c new file +5
-0+struct trace_overflow overflow; +struct trace_repeat repeat; +char buf[255 *8 ]; +}; +static union max_trace trace;I *think* this is only used in
opal_trace_read(), so it'd be nice if it was in there.
I'll have a look.
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arch/powerpc/platforms/powernv/opal-trace.c new file +31
-0+static bool trace_empty (const struct tracebuf *tb) +{ +const struct trace_repeat *rep; + +if (tb->rpos == tb->end) +return true; + +/* +* If we have a single element only, and it's a repeat buffer +* we've already seen every repeat for (yet which may be +* incremented in future), we're also empty. +*/ + rep = (void *)tb->buf + (be64_to_cpu (tb->rpos & tb->mask)); +if (be64_to_cpu (tb->end) !=be64_to_cpu (tb->rpos) +sizeof (*rep)) +return false; + +if (rep->type !=TRACE_REPEAT ) +return false; + +if (be16_to_cpu (rep->num) !=be32_to_cpu (tb->last_repeat)) +return false; + +return true; +} + +/* You can't read in parallel, so some locking required in caller. */ +static bool trace_get (union max_trace *t,struct tracebuf *tb) +{ +u64 start, rpos; + +if (trace_empty (tb))
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arch/powerpc/platforms/powernv/opal-trace.c line 67
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arch/powerpc/platforms/powernv/opal-trace.c new file +6
-0+return false; + +again: +/* +* The actual buffer is slightly larger than tbsize, so this +* memcpy is always valid. We don't seem to have tbsize anymore?
Indeed, I'll have a look.
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arch/powerpc/platforms/powernv/opal-trace.c new file +32
-0+*/ +memcpy (t, tb->buf +be64_to_cpu (tb->rpos & tb->mask), +be32_to_cpu (tb->max_size)); + +rmb ();/* read barrier, so we read tb->start after copying record. */ + + start =be64_to_cpu (tb->start); + rpos =be64_to_cpu (tb->rpos); + +/* Now, was that overwritten? */ +if (rpos < start) { +/* Create overflow record. */ + t->overflow.unused64 =0 ; + t->overflow.type =TRACE_OVERFLOW ; + t->overflow.len_div_8 =sizeof (t->overflow) /8 ; + t->overflow.bytes_missed =cpu_to_be64 (start - rpos); + tb->rpos =cpu_to_be64 (start); +return true; + } + +/* Repeat entries need special handling */ +if (t->hdr.type ==TRACE_REPEAT ) { +u32 num =be16_to_cpu (t->repeat.num); + +/* In case we've read some already... */ + t->repeat.num =cpu_to_be16 (num -be32_to_cpu (tb->last_repeat)); + +/* Record how many repeats we saw this time. */ + tb->last_repeat =cpu_to_be32 (num); + +/* Don't report an empty repeat buffer. */ +if (t->repeat.num ==0 ) {
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arch/powerpc/platforms/powernv/opal-trace.c line 104
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arch/powerpc/platforms/powernv/opal-trace.c new file +5
-0+/* +* This can't be the last buffer, otherwise +* trace_empty would have returned true. +*/ +BUG_ON (be64_to_cpu (tb->end) <= rpos + t->hdr.len_div_8 *8 );Can we just
WARN_ON()and bail, seeing as this is for debug. I'd hate to panic a customer system by dumping the trace buffer.
Yup.
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arch/powerpc/platforms/powernv/opal-trace.c new file +20
-0+/* Skip to next entry. */ + tb->rpos =cpu_to_be64 (rpos + t->hdr.len_div_8 *8 ); + goto again; + } + }else { + tb->last_repeat =0 ; + tb->rpos =cpu_to_be64 (rpos + t->hdr.len_div_8 *8 ); + } + +return true; +} + +/* Horrible polling interface, designed for dumping. */ +static ssize_t opal_trace_read (struct file *file,char __user *ubuf, +size_t count,loff_t *ppos) +{ +ssize_t err; +unsigned int i; + + err =mutex_lock_interruptible (&tracelock);
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arch/powerpc/platforms/powernv/opal-trace.c line 128
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arch/powerpc/platforms/powernv/opal-trace.c new file +4
-0+if (err) +return err; + +for (i =0 ; i < opal_num_tb; i++) {OK so I understand this now. You have multiple trace buffers, but you don't care about maintaining that separation. You just merge all the streams here into a single output stream.
Correct, the trace buffers can be per-cpu on the OPAL side.
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arch/powerpc/platforms/powernv/opal-trace.c new file +27
-0+if (trace_get (&trace, opal_tb[i])) { +size_t len = trace.hdr.len_div_8 *8 ; +if (len > count) + len = count; +if (copy_to_user (ubuf, &trace, len) !=0 ) + err = -EFAULT ; +else + err = len; +break ; + } + } + +mutex_unlock (&tracelock); +return err; +} + +static const struct file_operations opal_trace_fops = { + .read = opal_trace_read, + .open = simple_open, + .llseek = noop_llseek, +}; + +static int opal_tmask_set (void *data,u64 val) +{ + *(__be64 *)data =cpu_to_be64 (val); +return 0 ; +}
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arch/powerpc/platforms/powernv/opal-trace.c line 161
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arch/powerpc/platforms/powernv/opal-trace.c new file +6
-0+static int opal_tmask_get (void *data,u64 *val) +{ + *val =be64_to_cpup ((__be64 *)data); +return 0 ; +} +DEFINE_SIMPLE_ATTRIBUTE (opal_tmask, opal_tmask_get, opal_tmask_set,"%llx\n" );What is a tmask ?
Trace mask, it's a bitmask to enable individual tracers inside OPAL.
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I assume it's some mask of things we want traced?
Yes.
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arch/powerpc/platforms/powernv/opal-trace.c new file +12
-0+static int opal_trace_init (void ) +{ +const __be64 *traces; +int len, i, rc; +u64 tmask_phys; + +if (!opal_node) +return -ENODEV ; + + traces =of_get_property (opal_node,"ibm,opal-traces" , &len); +if (!traces) { + pr_warning("%s: OPAL node property \"ibm,opal-traces\""
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arch/powerpc/platforms/powernv/opal-trace.c line 179
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arch/powerpc/platforms/powernv/opal-trace.c new file +5
-0+ " not found\n", __func__); +return -ENODEV ; + } + + opal_num_tb = len / (sizeof (__be64) *2 );So I won't say the "b" word, but it'd be nice to have at least a comment on what the device tree property contains.
Hehe, allright :)
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arch/powerpc/platforms/powernv/opal-trace.c line 187
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arch/powerpc/platforms/powernv/opal-trace.c new file +8
-0+if (!opal_num_tb) { +pr_warning ("%s: OPAL traces property has invalid length %i\n" , + __func__, len); +return -EINVAL ; + } + opal_tb =kmalloc (sizeof (*opal_tb) * opal_num_tb,GFP_KERNEL ); +for (i =0 ; i < opal_num_tb; i++) + opal_tb[i] =__va (be64_to_cpu (traces[i*2 ]));Just
__va()? ie. it's already in the linear mapping somewhere?
All memory is. This is just part of one of the areas reserved by OPAL but it's in memory.
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arch/powerpc/platforms/powernv/opal-trace.c line 195
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arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+debugfs_create_file ("opal-trace" ,S_IRUSR , powerpc_debugfs_root, +NULL , &opal_trace_fops); + rc =of_property_read_u64 (opal_node,"ibm,opal-trace-mask" , + &tmask_phys); +if (!rc) + opal_tmask_p =__va (tmask_phys); +if (opal_tmask_p)If
tmask_physwas 0,opal_tmask_pis now 0xc00..00, so is that what we want to check?
No, that's fishy indeed.
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arch/powerpc/platforms/powernv/opal-trace.c line 202
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arch/powerpc/platforms/powernv/opal-trace.c new file +7
-0+debugfs_create_file ("opal-trace-mask" ,S_IRUSR |S_IWUSR , + powerpc_debugfs_root, opal_tmask_p, + &opal_tmask); +return 0 ; +} +module_init (opal_trace_init); +cheers
Ben.