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Message-ID: <20080309164607.443da6d1@daedalus.pq.iki.fi>
Date: Sun, 9 Mar 2008 16:46:07 +0200
From: Pekka Paalanen <pq@....fi>
To: Ingo Molnar <mingo@...e.hu>
Cc: Pekka Paalanen <pq@....fi>, linux-kernel@...r.kernel.org,
Christoph Hellwig <hch@...radead.org>,
Arjan van de Ven <arjan@...radead.org>,
Pavel Roskin <proski@....org>,
Steven Rostedt <rostedt@...dmis.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [RFC] mmiotrace full patch, preview 2
>From bc32dcfb4048bb74c774fd3de724bd38e8b98c2f Mon Sep 17 00:00:00 2001
From: Pekka Paalanen <pq@....fi>
Date: Sun, 9 Mar 2008 13:52:25 +0200
Subject: [PATCH] x86 mmiotrace: update preview 1 to preview 2
Kconfig.debug, Makefile and testmmiotrace.c style fixes.
Use real mutex instead of mutex.
Fix failure path in register probe func.
kmmio: RCU read-locked over single stepping.
Generate mapping id's.
Make mmio-mod.c built-in and rewrite its locking.
Add debugfs file to enable/disable mmiotracing.
kmmio: use irqsave spinlocks.
Lots of cleanups in mmio-mod.c
Marker file moved from /proc into debugfs.
Call mmiotrace entrypoints directly from ioremap.c.
Signed-off-by: Pekka Paalanen <pq@....fi>
---
arch/x86/Kconfig.debug | 20 +--
arch/x86/mm/Makefile | 2 +-
arch/x86/mm/ioremap.c | 9 +-
arch/x86/mm/kmmio.c | 72 ++++-----
arch/x86/mm/mmio-mod.c | 397 ++++++++++++++++++++++++++++---------------
arch/x86/mm/testmmiotrace.c | 15 +-
include/linux/mmiotrace.h | 18 ++-
7 files changed, 332 insertions(+), 201 deletions(-)
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 177fd06..4c4fea0 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -183,22 +183,19 @@ config SYSPROF
config MMIOTRACE_HOOKS
bool
- default n
config MMIOTRACE
- tristate "Memory mapped IO tracing"
+ bool "Memory mapped IO tracing"
depends on DEBUG_KERNEL && RELAY && DEBUG_FS
select MMIOTRACE_HOOKS
- default n
+ default y
help
- This will build a kernel module called mmiotrace.
- Making this a built-in is heavily discouraged.
-
- Mmiotrace traces Memory Mapped I/O access and is meant for debugging
- and reverse engineering. The kernel module offers wrapped
- versions of the ioremap family of functions. The driver to be traced
- must be modified to call these wrappers. A user space program is
- required to collect the MMIO data.
+ Mmiotrace traces Memory Mapped I/O access and is meant for
+ debugging and reverse engineering. It is called from the ioremap
+ implementation and works via page faults. A user space program is
+ required to collect the MMIO data from debugfs files.
+ Tracing is disabled by default and can be enabled from a debugfs
+ file.
See http://nouveau.freedesktop.org/wiki/MmioTrace
If you are not helping to develop drivers, say N.
@@ -206,7 +203,6 @@ config MMIOTRACE
config MMIOTRACE_TEST
tristate "Test module for mmiotrace"
depends on MMIOTRACE && m
- default n
help
This is a dumb module for testing mmiotrace. It is very dangerous
as it will write garbage to IO memory starting at a given address.
diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
index e8f6e34..e6821ed 100644
--- a/arch/x86/mm/Makefile
+++ b/arch/x86/mm/Makefile
@@ -5,7 +5,7 @@ obj-$(CONFIG_X86_32) += pgtable_32.o
obj-$(CONFIG_MMIOTRACE_HOOKS) += kmmio.o
obj-$(CONFIG_MMIOTRACE) += mmiotrace.o
-mmiotrace-objs := pf_in.o mmio-mod.o
+mmiotrace-y := pf_in.o mmio-mod.o
obj-$(CONFIG_MMIOTRACE_TEST) += testmmiotrace.o
obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 26b75e4..1253c35 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -12,6 +12,7 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
+#include <linux/mmiotrace.h>
#include <asm/cacheflush.h>
#include <asm/e820.h>
@@ -124,6 +125,7 @@ static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
unsigned long pfn, offset, last_addr, vaddr;
struct vm_struct *area;
pgprot_t prot;
+ void __iomem *ret_addr;
/* Don't allow wraparound or zero size */
last_addr = phys_addr + size - 1;
@@ -191,7 +193,10 @@ static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
return NULL;
}
- return (void __iomem *) (vaddr + offset);
+ ret_addr = (void __iomem *) (vaddr + offset);
+ mmiotrace_ioremap(phys_addr, size, ret_addr);
+
+ return ret_addr;
}
/**
@@ -249,6 +254,8 @@ void iounmap(volatile void __iomem *addr)
addr < phys_to_virt(ISA_END_ADDRESS))
return;
+ mmiotrace_iounmap(addr);
+
addr = (volatile void __iomem *)
(PAGE_MASK & (unsigned long __force)addr);
diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c
index 539a9b1..efb4679 100644
--- a/arch/x86/mm/kmmio.c
+++ b/arch/x86/mm/kmmio.c
@@ -19,6 +19,7 @@
#include <linux/preempt.h>
#include <linux/percpu.h>
#include <linux/kdebug.h>
+#include <linux/mutex.h>
#include <asm/io.h>
#include <asm/cacheflush.h>
#include <asm/errno.h>
@@ -59,7 +60,7 @@ struct kmmio_context {
static int kmmio_die_notifier(struct notifier_block *nb, unsigned long val,
void *args);
-static DECLARE_MUTEX(kmmio_init_mutex);
+static DEFINE_MUTEX(kmmio_init_mutex);
static DEFINE_SPINLOCK(kmmio_lock);
/* These are protected by kmmio_lock */
@@ -90,7 +91,7 @@ static struct notifier_block nb_die = {
*/
void reference_kmmio(void)
{
- down(&kmmio_init_mutex);
+ mutex_lock(&kmmio_init_mutex);
spin_lock_irq(&kmmio_lock);
if (!kmmio_initialized) {
int i;
@@ -101,7 +102,7 @@ void reference_kmmio(void)
}
kmmio_initialized++;
spin_unlock_irq(&kmmio_lock);
- up(&kmmio_init_mutex);
+ mutex_unlock(&kmmio_init_mutex);
}
EXPORT_SYMBOL_GPL(reference_kmmio);
@@ -115,7 +116,7 @@ void unreference_kmmio(void)
{
bool unreg = false;
- down(&kmmio_init_mutex);
+ mutex_lock(&kmmio_init_mutex);
spin_lock_irq(&kmmio_lock);
if (kmmio_initialized == 1) {
@@ -128,7 +129,7 @@ void unreference_kmmio(void)
if (unreg)
unregister_die_notifier(&nb_die); /* calls sync_rcu() */
- up(&kmmio_init_mutex);
+ mutex_unlock(&kmmio_init_mutex);
}
EXPORT_SYMBOL(unreference_kmmio);
@@ -244,17 +245,13 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
* Preemption is now disabled to prevent process switch during
* single stepping. We can only handle one active kmmio trace
* per cpu, so ensure that we finish it before something else
- * gets to run.
- *
- * XXX what if an interrupt occurs between returning from
- * do_page_fault() and entering the single-step exception handler?
- * And that interrupt triggers a kmmio trap?
- * XXX If we tracing an interrupt service routine or whatever, is
- * this enough to keep it on the current cpu?
+ * gets to run. We also hold the RCU read lock over single
+ * stepping to avoid looking up the probe and kmmio_fault_page
+ * again.
*/
preempt_disable();
-
rcu_read_lock();
+
faultpage = get_kmmio_fault_page(addr);
if (!faultpage) {
/*
@@ -287,14 +284,24 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
if (ctx->probe && ctx->probe->pre_handler)
ctx->probe->pre_handler(ctx->probe, regs, addr);
+ /*
+ * Enable single-stepping and disable interrupts for the faulting
+ * context. Local interrupts must not get enabled during stepping.
+ */
regs->flags |= TF_MASK;
regs->flags &= ~IF_MASK;
/* Now we set present bit in PTE and single step. */
disarm_kmmio_fault_page(ctx->fpage->page, NULL);
+ /*
+ * If another cpu accesses the same page while we are stepping,
+ * the access will not be caught. It will simply succeed and the
+ * only downside is we lose the event. If this becomes a problem,
+ * the user should drop to single cpu before tracing.
+ */
+
put_cpu_var(kmmio_ctx);
- rcu_read_unlock();
return 1;
no_kmmio_ctx:
@@ -313,32 +320,15 @@ no_kmmio:
static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
{
int ret = 0;
- struct kmmio_probe *probe;
- struct kmmio_fault_page *faultpage;
struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx);
if (!ctx->active)
goto out;
- rcu_read_lock();
-
- faultpage = get_kmmio_fault_page(ctx->addr);
- probe = get_kmmio_probe(ctx->addr);
- if (faultpage != ctx->fpage || probe != ctx->probe) {
- /*
- * The trace setup changed after kmmio_handler() and before
- * running this respective post handler. User does not want
- * the result anymore.
- */
- ctx->probe = NULL;
- ctx->fpage = NULL;
- }
-
if (ctx->probe && ctx->probe->post_handler)
ctx->probe->post_handler(ctx->probe, condition, regs);
- if (ctx->fpage)
- arm_kmmio_fault_page(ctx->fpage->page, NULL);
+ arm_kmmio_fault_page(ctx->fpage->page, NULL);
regs->flags &= ~TF_MASK;
regs->flags |= ctx->saved_flags;
@@ -346,6 +336,7 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
/* These were acquired in kmmio_handler(). */
ctx->active--;
BUG_ON(ctx->active);
+ rcu_read_unlock();
preempt_enable_no_resched();
/*
@@ -355,8 +346,6 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
*/
if (!(regs->flags & TF_MASK))
ret = 1;
-
- rcu_read_unlock();
out:
put_cpu_var(kmmio_ctx);
return ret;
@@ -411,15 +400,16 @@ static void release_kmmio_fault_page(unsigned long page,
int register_kmmio_probe(struct kmmio_probe *p)
{
+ unsigned long flags;
int ret = 0;
unsigned long size = 0;
- spin_lock_irq(&kmmio_lock);
- kmmio_count++;
+ spin_lock_irqsave(&kmmio_lock, flags);
if (get_kmmio_probe(p->addr)) {
ret = -EEXIST;
goto out;
}
+ kmmio_count++;
list_add_rcu(&p->list, &kmmio_probes);
while (size < p->len) {
if (add_kmmio_fault_page(p->addr + size))
@@ -427,7 +417,7 @@ int register_kmmio_probe(struct kmmio_probe *p)
size += PAGE_SIZE;
}
out:
- spin_unlock_irq(&kmmio_lock);
+ spin_unlock_irqrestore(&kmmio_lock, flags);
/*
* XXX: What should I do here?
* Here was a call to global_flush_tlb(), but it does not exist
@@ -478,7 +468,8 @@ static void remove_kmmio_fault_pages(struct rcu_head *head)
/*
* Remove a kmmio probe. You have to synchronize_rcu() before you can be
- * sure that the callbacks will not be called anymore.
+ * sure that the callbacks will not be called anymore. Only after that
+ * you may actually release your struct kmmio_probe.
*
* Unregistering a kmmio fault page has three steps:
* 1. release_kmmio_fault_page()
@@ -490,18 +481,19 @@ static void remove_kmmio_fault_pages(struct rcu_head *head)
*/
void unregister_kmmio_probe(struct kmmio_probe *p)
{
+ unsigned long flags;
unsigned long size = 0;
struct kmmio_fault_page *release_list = NULL;
struct kmmio_delayed_release *drelease;
- spin_lock_irq(&kmmio_lock);
+ spin_lock_irqsave(&kmmio_lock, flags);
while (size < p->len) {
release_kmmio_fault_page(p->addr + size, &release_list);
size += PAGE_SIZE;
}
list_del_rcu(&p->list);
kmmio_count--;
- spin_unlock_irq(&kmmio_lock);
+ spin_unlock_irqrestore(&kmmio_lock, flags);
drelease = kmalloc(sizeof(*drelease), GFP_ATOMIC);
if (!drelease) {
diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index e1a5085..7386440 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/mmio-mod.c
@@ -19,6 +19,8 @@
*
* Derived from the read-mod example from relay-examples by Tom Zanussi.
*/
+#define DEBUG 1
+
#include <linux/module.h>
#include <linux/relay.h>
#include <linux/debugfs.h>
@@ -34,12 +36,12 @@
#include "pf_in.h"
-/* This app's relay channel files will appear in /debug/mmio-trace */
-#define APP_DIR "mmio-trace"
-/* the marker injection file in /proc */
-#define MARKER_FILE "mmio-marker"
+#define NAME "mmiotrace: "
-#define MODULE_NAME "mmiotrace"
+/* This app's relay channel files will appear in /debug/mmio-trace */
+static const char APP_DIR[] = "mmio-trace";
+/* the marker injection file in /debug/APP_DIR */
+static const char MARKER_FILE[] = "mmio-marker";
struct trap_reason {
unsigned long addr;
@@ -48,6 +50,15 @@ struct trap_reason {
int active_traces;
};
+struct remap_trace {
+ struct list_head list;
+ struct kmmio_probe probe;
+ unsigned long phys;
+ unsigned long id;
+};
+
+static const size_t subbuf_size = 256*1024;
+
/* Accessed per-cpu. */
static DEFINE_PER_CPU(struct trap_reason, pf_reason);
static DEFINE_PER_CPU(struct mm_io_header_rw, cpu_trace);
@@ -55,33 +66,53 @@ static DEFINE_PER_CPU(struct mm_io_header_rw, cpu_trace);
/* Access to this is not per-cpu. */
static DEFINE_PER_CPU(atomic_t, dropped);
-static struct file_operations mmio_fops = {
- .owner = THIS_MODULE,
-};
+static struct dentry *dir;
+static struct dentry *enabled_file;
+static struct dentry *marker_file;
-static const size_t subbuf_size = 256*1024;
+static DEFINE_MUTEX(mmiotrace_mutex);
+static DEFINE_SPINLOCK(trace_lock);
+static atomic_t mmiotrace_enabled;
+static LIST_HEAD(trace_list); /* struct remap_trace */
static struct rchan *chan;
-static struct dentry *dir;
-static struct proc_dir_entry *proc_marker_file;
+
+/*
+ * Locking in this file:
+ * - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections.
+ * - mmiotrace_enabled may be modified only when holding mmiotrace_mutex
+ * and trace_lock.
+ * - Routines depending on is_enabled() must take trace_lock.
+ * - trace_list users must hold trace_lock.
+ * - is_enabled() guarantees that chan is valid.
+ * - pre/post callbacks assume the effect of is_enabled() being true.
+ */
/* module parameters */
-static unsigned int n_subbufs = 32*4;
-static unsigned long filter_offset;
-static int nommiotrace;
-static int ISA_trace;
-static int trace_pc;
+static unsigned int n_subbufs = 32*4;
+static unsigned long filter_offset;
+static int nommiotrace;
+static int ISA_trace;
+static int trace_pc;
+static int enable_now;
module_param(n_subbufs, uint, 0);
module_param(filter_offset, ulong, 0);
module_param(nommiotrace, bool, 0);
module_param(ISA_trace, bool, 0);
module_param(trace_pc, bool, 0);
+module_param(enable_now, bool, 0);
MODULE_PARM_DESC(n_subbufs, "Number of 256kB buffers, default 128.");
MODULE_PARM_DESC(filter_offset, "Start address of traced mappings.");
MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing.");
MODULE_PARM_DESC(ISA_trace, "Do not exclude the low ISA range.");
MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions.");
+MODULE_PARM_DESC(enable_now, "Start mmiotracing immediately on module load.");
+
+static bool is_enabled(void)
+{
+ return atomic_read(&mmiotrace_enabled);
+}
static void record_timestamp(struct mm_io_header *header)
{
@@ -93,15 +124,15 @@ static void record_timestamp(struct mm_io_header *header)
}
/*
- * Write callback for the /proc entry:
+ * Write callback for the debugfs entry:
* Read a marker and write it to the mmio trace log
*/
-static int write_marker(struct file *file, const char __user *buffer,
- unsigned long count, void *data)
+static ssize_t write_marker(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
{
char *event = NULL;
struct mm_io_header *headp;
- int len = (count > 65535) ? 65535 : count;
+ ssize_t len = (count > 65535) ? 65535 : count;
event = kzalloc(sizeof(*headp) + len, GFP_KERNEL);
if (!event)
@@ -117,7 +148,12 @@ static int write_marker(struct file *file, const char __user *buffer,
return -EFAULT;
}
- relay_write(chan, event, sizeof(*headp) + len);
+ spin_lock_irq(&trace_lock);
+ if (is_enabled())
+ relay_write(chan, event, sizeof(*headp) + len);
+ else
+ len = -EINVAL;
+ spin_unlock_irq(&trace_lock);
kfree(event);
return len;
}
@@ -128,19 +164,18 @@ static void print_pte(unsigned long address)
pte_t *pte = lookup_address(address, &level);
if (!pte) {
- pr_err(MODULE_NAME ": Error in %s: no pte for page 0x%08lx\n",
+ pr_err(NAME "Error in %s: no pte for page 0x%08lx\n",
__func__, address);
return;
}
if (level == PG_LEVEL_2M) {
- pr_emerg(MODULE_NAME ": 4MB pages are not currently "
- "supported: %lx\n", address);
+ pr_emerg(NAME "4MB pages are not currently supported: "
+ "0x%08lx\n", address);
BUG();
}
- pr_info(MODULE_NAME ": pte for 0x%lx: 0x%lx 0x%lx\n",
- address, pte_val(*pte),
- pte_val(*pte) & _PAGE_PRESENT);
+ pr_info(NAME "pte for 0x%lx: 0x%lx 0x%lx\n", address, pte_val(*pte),
+ pte_val(*pte) & _PAGE_PRESENT);
}
/*
@@ -150,22 +185,18 @@ static void print_pte(unsigned long address)
static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
{
const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
- pr_emerg(MODULE_NAME ": unexpected fault for address: %lx, "
- "last fault for address: %lx\n",
+ pr_emerg(NAME "unexpected fault for address: 0x%08lx, "
+ "last fault for address: 0x%08lx\n",
addr, my_reason->addr);
print_pte(addr);
+ print_symbol(KERN_EMERG "faulting IP is at %s\n", regs->ip);
+ print_symbol(KERN_EMERG "last faulting IP was at %s\n", my_reason->ip);
#ifdef __i386__
- print_symbol(KERN_EMERG "faulting EIP is at %s\n", regs->ip);
- print_symbol(KERN_EMERG "last faulting EIP was at %s\n",
- my_reason->ip);
pr_emerg("eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n",
regs->ax, regs->bx, regs->cx, regs->dx);
pr_emerg("esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n",
regs->si, regs->di, regs->bp, regs->sp);
#else
- print_symbol(KERN_EMERG "faulting RIP is at %s\n", regs->ip);
- print_symbol(KERN_EMERG "last faulting RIP was at %s\n",
- my_reason->ip);
pr_emerg("rax: %016lx rcx: %016lx rdx: %016lx\n",
regs->ax, regs->cx, regs->dx);
pr_emerg("rsi: %016lx rdi: %016lx rbp: %016lx rsp: %016lx\n",
@@ -197,6 +228,10 @@ static void pre(struct kmmio_probe *p, struct pt_regs *regs,
my_trace->header.pid = 0;
my_trace->header.data_len = sizeof(struct mm_io_rw);
my_trace->rw.address = addr;
+ /*
+ * struct remap_trace *trace = p->user_data;
+ * phys = addr - trace->probe.addr + trace->phys;
+ */
/*
* Only record the program counter when requested.
@@ -246,15 +281,10 @@ static void post(struct kmmio_probe *p, unsigned long condition,
struct trap_reason *my_reason = &get_cpu_var(pf_reason);
struct mm_io_header_rw *my_trace = &get_cpu_var(cpu_trace);
- /*
- * XXX: This might not get called, if the probe is removed while
- * trace hit is on flight.
- */
-
/* this should always return the active_trace count to 0 */
my_reason->active_traces--;
if (my_reason->active_traces) {
- pr_emerg(MODULE_NAME ": unexpected post handler");
+ pr_emerg(NAME "unexpected post handler");
BUG();
}
@@ -284,20 +314,23 @@ static int subbuf_start_handler(struct rchan_buf *buf, void *subbuf,
int count;
if (relay_buf_full(buf)) {
if (atomic_inc_return(drop) == 1)
- pr_err(MODULE_NAME ": cpu %d buffer full!\n", cpu);
+ pr_err(NAME "cpu %d buffer full!\n", cpu);
return 0;
}
count = atomic_read(drop);
if (count) {
- pr_err(MODULE_NAME ": cpu %d buffer no longer full, "
- "missed %d events.\n",
- cpu, count);
+ pr_err(NAME "cpu %d buffer no longer full, missed %d events.\n",
+ cpu, count);
atomic_sub(count, drop);
}
return 1;
}
+static struct file_operations mmio_fops = {
+ .owner = THIS_MODULE,
+};
+
/* file_create() callback. Creates relay file in debugfs. */
static struct dentry *create_buf_file_handler(const char *filename,
struct dentry *parent,
@@ -333,34 +366,10 @@ static struct rchan_callbacks relay_callbacks = {
.remove_buf_file = remove_buf_file_handler,
};
-/*
- * create_channel - creates channel /debug/APP_DIR/cpuXXX
- * Returns channel on success, NULL otherwise
- */
-static struct rchan *create_channel(unsigned size, unsigned n)
-{
- return relay_open("cpu", dir, size, n, &relay_callbacks, NULL);
-}
-
-/* destroy_channel - destroys channel /debug/APP_DIR/cpuXXX */
-static void destroy_channel(void)
-{
- if (chan) {
- relay_close(chan);
- chan = NULL;
- }
-}
-
-struct remap_trace {
- struct list_head list;
- struct kmmio_probe probe;
-};
-static LIST_HEAD(trace_list);
-static DEFINE_SPINLOCK(trace_list_lock);
-
-static void do_ioremap_trace_core(unsigned long offset, unsigned long size,
+static void ioremap_trace_core(unsigned long offset, unsigned long size,
void __iomem *addr)
{
+ static atomic_t next_id;
struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
struct mm_io_header_map event = {
.header = {
@@ -380,61 +389,49 @@ static void do_ioremap_trace_core(unsigned long offset, unsigned long size,
};
record_timestamp(&event.header);
+ if (!trace) {
+ pr_err(NAME "kmalloc failed in ioremap\n");
+ return;
+ }
+
*trace = (struct remap_trace) {
.probe = {
.addr = (unsigned long)addr,
.len = size,
.pre_handler = pre,
.post_handler = post,
- }
+ .user_data = trace
+ },
+ .phys = offset,
+ .id = atomic_inc_return(&next_id)
};
+ spin_lock_irq(&trace_lock);
+ if (!is_enabled())
+ goto not_enabled;
+
relay_write(chan, &event, sizeof(event));
- spin_lock(&trace_list_lock);
list_add_tail(&trace->list, &trace_list);
- spin_unlock(&trace_list_lock);
if (!nommiotrace)
register_kmmio_probe(&trace->probe);
+
+not_enabled:
+ spin_unlock_irq(&trace_lock);
}
-static void ioremap_trace_core(unsigned long offset, unsigned long size,
- void __iomem *addr)
+void
+mmiotrace_ioremap(unsigned long offset, unsigned long size, void __iomem *addr)
{
- if ((filter_offset) && (offset != filter_offset))
+ if (!is_enabled()) /* recheck and proper locking in *_core() */
return;
- /* Don't trace the low PCI/ISA area, it's always mapped.. */
- if (!ISA_trace && (offset < ISA_END_ADDRESS) &&
- (offset + size > ISA_START_ADDRESS)) {
- pr_notice(MODULE_NAME ": Ignoring map of low PCI/ISA area "
- "(0x%lx-0x%lx)\n",
- offset, offset + size);
+ pr_debug(NAME "ioremap_*(0x%lx, 0x%lx) = %p\n", offset, size, addr);
+ if ((filter_offset) && (offset != filter_offset))
return;
- }
- do_ioremap_trace_core(offset, size, addr);
-}
-
-void __iomem *ioremap_cache_trace(unsigned long offset, unsigned long size)
-{
- void __iomem *p = ioremap_cache(offset, size);
- pr_debug(MODULE_NAME ": ioremap_cache(0x%lx, 0x%lx) = %p\n",
- offset, size, p);
- ioremap_trace_core(offset, size, p);
- return p;
+ ioremap_trace_core(offset, size, addr);
}
-EXPORT_SYMBOL(ioremap_cache_trace);
-void __iomem *ioremap_nocache_trace(unsigned long offset, unsigned long size)
-{
- void __iomem *p = ioremap_nocache(offset, size);
- pr_debug(MODULE_NAME ": ioremap_nocache(0x%lx, 0x%lx) = %p\n",
- offset, size, p);
- ioremap_trace_core(offset, size, p);
- return p;
-}
-EXPORT_SYMBOL(ioremap_nocache_trace);
-
-void iounmap_trace(volatile void __iomem *addr)
+static void iounmap_trace_core(volatile void __iomem *addr)
{
struct mm_io_header_map event = {
.header = {
@@ -454,84 +451,212 @@ void iounmap_trace(volatile void __iomem *addr)
};
struct remap_trace *trace;
struct remap_trace *tmp;
- pr_debug(MODULE_NAME ": Unmapping %p.\n", addr);
+ struct remap_trace *found_trace = NULL;
+
+ pr_debug(NAME "Unmapping %p.\n", addr);
record_timestamp(&event.header);
- spin_lock(&trace_list_lock);
+ spin_lock_irq(&trace_lock);
+ if (!is_enabled())
+ goto not_enabled;
+
list_for_each_entry_safe(trace, tmp, &trace_list, list) {
if ((unsigned long)addr == trace->probe.addr) {
if (!nommiotrace)
unregister_kmmio_probe(&trace->probe);
list_del(&trace->list);
- kfree(trace);
+ found_trace = trace;
break;
}
}
- spin_unlock(&trace_list_lock);
relay_write(chan, &event, sizeof(event));
- iounmap(addr);
+
+not_enabled:
+ spin_unlock_irq(&trace_lock);
+ if (found_trace) {
+ synchronize_rcu(); /* unregister_kmmio_probe() requirement */
+ kfree(found_trace);
+ }
+}
+
+void mmiotrace_iounmap(volatile void __iomem *addr)
+{
+ might_sleep();
+ if (is_enabled()) /* recheck and proper locking in *_core() */
+ iounmap_trace_core(addr);
}
-EXPORT_SYMBOL(iounmap_trace);
static void clear_trace_list(void)
{
struct remap_trace *trace;
struct remap_trace *tmp;
- spin_lock(&trace_list_lock);
- list_for_each_entry_safe(trace, tmp, &trace_list, list) {
- pr_warning(MODULE_NAME ": purging non-iounmapped "
+ /*
+ * No locking required, because the caller ensures we are in a
+ * critical section via mutex, and is_enabled() is false,
+ * i.e. nothing can traverse or modify this list.
+ * Caller also ensures is_enabled() cannot change.
+ */
+ list_for_each_entry(trace, &trace_list, list) {
+ pr_notice(NAME "purging non-iounmapped "
"trace @0x%08lx, size 0x%lx.\n",
trace->probe.addr, trace->probe.len);
if (!nommiotrace)
unregister_kmmio_probe(&trace->probe);
+ }
+ synchronize_rcu(); /* unregister_kmmio_probe() requirement */
+
+ list_for_each_entry_safe(trace, tmp, &trace_list, list) {
list_del(&trace->list);
kfree(trace);
+ }
+}
+
+static ssize_t read_enabled_file_bool(struct file *file,
+ char __user *user_buf, size_t count, loff_t *ppos)
+{
+ char buf[3];
+
+ if (is_enabled())
+ buf[0] = '1';
+ else
+ buf[0] = '0';
+ buf[1] = '\n';
+ buf[2] = '\0';
+ return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+}
+
+static void enable_mmiotrace(void);
+static void disable_mmiotrace(void);
+
+static ssize_t write_enabled_file_bool(struct file *file,
+ const char __user *user_buf, size_t count, loff_t *ppos)
+{
+ char buf[32];
+ int buf_size = min(count, (sizeof(buf)-1));
+
+ if (copy_from_user(buf, user_buf, buf_size))
+ return -EFAULT;
+
+ switch (buf[0]) {
+ case 'y':
+ case 'Y':
+ case '1':
+ enable_mmiotrace();
+ break;
+ case 'n':
+ case 'N':
+ case '0':
+ disable_mmiotrace();
break;
}
- spin_unlock(&trace_list_lock);
+
+ return count;
+}
+
+/* this ripped from kernel/kprobes.c */
+static struct file_operations fops_enabled = {
+ .owner = THIS_MODULE,
+ .read = read_enabled_file_bool,
+ .write = write_enabled_file_bool
+};
+
+static struct file_operations fops_marker = {
+ .owner = THIS_MODULE,
+ .write = write_marker
+};
+
+static void enable_mmiotrace(void)
+{
+ mutex_lock(&mmiotrace_mutex);
+ if (is_enabled())
+ goto out;
+
+ chan = relay_open("cpu", dir, subbuf_size, n_subbufs,
+ &relay_callbacks, NULL);
+ if (!chan) {
+ pr_err(NAME "relay app channel creation failed.\n");
+ goto out;
+ }
+
+ reference_kmmio();
+
+ marker_file = debugfs_create_file("marker", 0660, dir, NULL,
+ &fops_marker);
+ if (!marker_file)
+ pr_err(NAME "marker file creation failed.\n");
+
+ if (nommiotrace)
+ pr_info(NAME "MMIO tracing disabled.\n");
+ if (ISA_trace)
+ pr_warning(NAME "Warning! low ISA range will be traced.\n");
+ spin_lock_irq(&trace_lock);
+ atomic_inc(&mmiotrace_enabled);
+ spin_unlock_irq(&trace_lock);
+ pr_info(NAME "enabled.\n");
+out:
+ mutex_unlock(&mmiotrace_mutex);
+}
+
+static void disable_mmiotrace(void)
+{
+ mutex_lock(&mmiotrace_mutex);
+ if (!is_enabled())
+ goto out;
+
+ spin_lock_irq(&trace_lock);
+ atomic_dec(&mmiotrace_enabled);
+ BUG_ON(is_enabled());
+ spin_unlock_irq(&trace_lock);
+
+ clear_trace_list(); /* guarantees: no more kmmio callbacks */
+ unreference_kmmio();
+ if (marker_file) {
+ debugfs_remove(marker_file);
+ marker_file = NULL;
+ }
+ if (chan) {
+ relay_close(chan);
+ chan = NULL;
+ }
+
+ pr_info(NAME "disabled.\n");
+out:
+ mutex_unlock(&mmiotrace_mutex);
}
static int __init init(void)
{
+ pr_debug(NAME "load...\n");
if (n_subbufs < 2)
return -EINVAL;
dir = debugfs_create_dir(APP_DIR, NULL);
if (!dir) {
- pr_err(MODULE_NAME ": Couldn't create relay app directory.\n");
+ pr_err(NAME "Couldn't create relay app directory.\n");
return -ENOMEM;
}
- chan = create_channel(subbuf_size, n_subbufs);
- if (!chan) {
+ enabled_file = debugfs_create_file("enabled", 0600, dir, NULL,
+ &fops_enabled);
+ if (!enabled_file) {
+ pr_err(NAME "Couldn't create enabled file.\n");
debugfs_remove(dir);
- pr_err(MODULE_NAME ": relay app channel creation failed\n");
return -ENOMEM;
}
- reference_kmmio();
-
- proc_marker_file = create_proc_entry(MARKER_FILE, 0, NULL);
- if (proc_marker_file)
- proc_marker_file->write_proc = write_marker;
+ if (enable_now)
+ enable_mmiotrace();
- pr_debug(MODULE_NAME ": loaded.\n");
- if (nommiotrace)
- pr_info(MODULE_NAME ": MMIO tracing disabled.\n");
- if (ISA_trace)
- pr_warning(MODULE_NAME ": Warning! low ISA range will be "
- "traced.\n");
return 0;
}
static void __exit cleanup(void)
{
- pr_debug(MODULE_NAME ": unload...\n");
- clear_trace_list();
- unreference_kmmio();
- remove_proc_entry(MARKER_FILE, NULL);
- destroy_channel();
+ pr_debug(NAME "unload...\n");
+ if (enabled_file)
+ debugfs_remove(enabled_file);
+ disable_mmiotrace();
if (dir)
debugfs_remove(dir);
}
diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index 5ecff57..cfa60b2 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -4,10 +4,6 @@
#include <linux/module.h>
#include <asm/io.h>
-extern void __iomem *ioremap_nocache_trace(unsigned long offset,
- unsigned long size);
-extern void iounmap_trace(volatile void __iomem *addr);
-
#define MODULE_NAME "testmmiotrace"
static unsigned long mmio_address;
@@ -28,25 +24,24 @@ static void do_write_test(void __iomem *p)
static void do_read_test(void __iomem *p)
{
unsigned int i;
- volatile unsigned int v;
for (i = 0; i < 256; i++)
- v = ioread8(p + i);
+ ioread8(p + i);
for (i = 1024; i < (5 * 1024); i += 2)
- v = ioread16(p + i);
+ ioread16(p + i);
for (i = (5 * 1024); i < (16 * 1024); i += 4)
- v = ioread32(p + i);
+ ioread32(p + i);
}
static void do_test(void)
{
- void __iomem *p = ioremap_nocache_trace(mmio_address, 0x4000);
+ void __iomem *p = ioremap_nocache(mmio_address, 0x4000);
if (!p) {
pr_err(MODULE_NAME ": could not ioremap, aborting.\n");
return;
}
do_write_test(p);
do_read_test(p);
- iounmap_trace(p);
+ iounmap(p);
}
static int __init init(void)
diff --git a/include/linux/mmiotrace.h b/include/linux/mmiotrace.h
index d87a6cd..cb5efd0 100644
--- a/include/linux/mmiotrace.h
+++ b/include/linux/mmiotrace.h
@@ -16,11 +16,12 @@ typedef void (*kmmio_post_handler_t)(struct kmmio_probe *,
unsigned long condition, struct pt_regs *);
struct kmmio_probe {
- struct list_head list;
+ struct list_head list; /* kmmio internal list */
unsigned long addr; /* start location of the probe point */
unsigned long len; /* length of the probe region */
kmmio_pre_handler_t pre_handler; /* Called before addr is executed. */
kmmio_post_handler_t post_handler; /* Called after addr is executed */
+ void *user_data;
};
/* kmmio is active by some kmmio_probes? */
@@ -38,6 +39,21 @@ extern void unregister_kmmio_probe(struct kmmio_probe *p);
/* Called from page fault handler. */
extern int kmmio_handler(struct pt_regs *regs, unsigned long addr);
+/* Called from ioremap.c */
+#ifdef CONFIG_MMIOTRACE
+extern void
+mmiotrace_ioremap(unsigned long offset, unsigned long size, void __iomem *addr);
+extern void mmiotrace_iounmap(volatile void __iomem *addr);
+#else
+static inline void
+mmiotrace_ioremap(unsigned long offset, unsigned long size, void __iomem *addr)
+{
+}
+static inline void mmiotrace_iounmap(volatile void __iomem *addr)
+{
+}
+#endif /* CONFIG_MMIOTRACE_HOOKS */
+
#endif /* __KERNEL__ */
--
1.5.3.7
--
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