x86: mmiotrace full patch, preview 1
kmmio.c handles the list of mmio probes with callbacks, list of traced
pages, and attaching into the page fault handler and die notifier. It
arms, traps and disarms the given pages, this is the core of mmiotrace.
mmio-mod.c is a user interface, hooking into ioremap functions and
registering the mmio probes. It also decodes the required information
from trapped mmio accesses via the pre and post callbacks in each probe.
Currently, hooking into ioremap functions works by redefining the symbols
of the target (binary) kernel module, so that it calls the traced
versions of the functions.
The most notable changes done since the last discussion are:
- kmmio.c is a built-in, not part of the module
- direct call from fault.c to kmmio.c, removing all dynamic hooks
- prepare for unregistering probes at any time
- make kmmio re-initializable and accessible to more than one user
- rewrite kmmio locking to remove all spinlocks from page fault path
Can I abuse call_rcu() like I do in kmmio.c:unregister_kmmio_probe()
or is there a better way?
The function called via call_rcu() itself calls call_rcu() again,
will this work or break? There I need a second grace period for RCU
after the first grace period for page faults.
Mmiotrace itself (mmio-mod.c) is still a module, I am going to attack
that next. At some point I will start looking into how to make mmiotrace
a tracer component of ftrace (thanks for the hint, Ingo). Ftrace should
make the user space part of mmiotracing as simple as
'cat /debug/trace/mmio > dump.txt'.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/mmiotrace/mmio-mod.c b/arch/x86/kernel/mmiotrace/mmio-mod.c
index f9c6092..e1a5085 100644
--- a/arch/x86/kernel/mmiotrace/mmio-mod.c
+++ b/arch/x86/kernel/mmiotrace/mmio-mod.c
@@ -32,7 +32,6 @@
#include <asm/atomic.h>
#include <linux/percpu.h>
-#include "kmmio.h"
#include "pf_in.h"
/* This app's relay channel files will appear in /debug/mmio-trace */
@@ -129,18 +128,17 @@
pte_t *pte = lookup_address(address, &level);
if (!pte) {
- printk(KERN_ERR "Error in %s: no pte for page 0x%08lx\n",
- __FUNCTION__, address);
+ pr_err(MODULE_NAME ": Error in %s: no pte for page 0x%08lx\n",
+ __func__, address);
return;
}
if (level == PG_LEVEL_2M) {
- printk(KERN_EMERG MODULE_NAME ": 4MB pages are not "
- "currently supported: %lx\n",
- address);
+ pr_emerg(MODULE_NAME ": 4MB pages are not currently "
+ "supported: %lx\n", address);
BUG();
}
- printk(KERN_DEBUG MODULE_NAME ": pte for 0x%lx: 0x%lx 0x%lx\n",
+ pr_info(MODULE_NAME ": pte for 0x%lx: 0x%lx 0x%lx\n",
address, pte_val(*pte),
pte_val(*pte) & _PAGE_PRESENT);
}
@@ -152,7 +150,7 @@
static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
{
const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
- printk(KERN_EMERG MODULE_NAME ": unexpected fault for address: %lx, "
+ pr_emerg(MODULE_NAME ": unexpected fault for address: %lx, "
"last fault for address: %lx\n",
addr, my_reason->addr);
print_pte(addr);
@@ -160,20 +158,17 @@
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);
- printk(KERN_EMERG
- "eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n",
+ pr_emerg("eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n",
regs->ax, regs->bx, regs->cx, regs->dx);
- printk(KERN_EMERG
- "esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n",
+ 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);
- printk(KERN_EMERG "rax: %016lx rcx: %016lx rdx: %016lx\n",
+ pr_emerg("rax: %016lx rcx: %016lx rdx: %016lx\n",
regs->ax, regs->cx, regs->dx);
- printk(KERN_EMERG "rsi: %016lx rdi: %016lx "
- "rbp: %016lx rsp: %016lx\n",
+ pr_emerg("rsi: %016lx rdi: %016lx rbp: %016lx rsp: %016lx\n",
regs->si, regs->di, regs->bp, regs->sp);
#endif
put_cpu_var(pf_reason);
@@ -251,10 +246,15 @@
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) {
- printk(KERN_EMERG MODULE_NAME ": unexpected post handler");
+ pr_emerg(MODULE_NAME ": unexpected post handler");
BUG();
}
@@ -283,16 +283,15 @@
atomic_t *drop = &per_cpu(dropped, cpu);
int count;
if (relay_buf_full(buf)) {
- if (atomic_inc_return(drop) == 1) {
- printk(KERN_ERR MODULE_NAME ": cpu %d buffer full!\n",
- cpu);
- }
+ if (atomic_inc_return(drop) == 1)
+ pr_err(MODULE_NAME ": cpu %d buffer full!\n", cpu);
return 0;
- } else if ((count = atomic_read(drop))) {
- printk(KERN_ERR MODULE_NAME
- ": cpu %d buffer no longer full, "
- "missed %d events.\n",
- cpu, count);
+ }
+ count = atomic_read(drop);
+ if (count) {
+ pr_err(MODULE_NAME ": cpu %d buffer no longer full, "
+ "missed %d events.\n",
+ cpu, count);
atomic_sub(count, drop);
}
@@ -407,8 +406,8 @@
/* Don't trace the low PCI/ISA area, it's always mapped.. */
if (!ISA_trace && (offset < ISA_END_ADDRESS) &&
(offset + size > ISA_START_ADDRESS)) {
- printk(KERN_NOTICE MODULE_NAME ": Ignoring map of low "
- "PCI/ISA area (0x%lx-0x%lx)\n",
+ pr_notice(MODULE_NAME ": Ignoring map of low PCI/ISA area "
+ "(0x%lx-0x%lx)\n",
offset, offset + size);
return;
}
@@ -418,7 +417,7 @@
void __iomem *ioremap_cache_trace(unsigned long offset, unsigned long size)
{
void __iomem *p = ioremap_cache(offset, size);
- printk(KERN_DEBUG MODULE_NAME ": ioremap_cache(0x%lx, 0x%lx) = %p\n",
+ pr_debug(MODULE_NAME ": ioremap_cache(0x%lx, 0x%lx) = %p\n",
offset, size, p);
ioremap_trace_core(offset, size, p);
return p;
@@ -428,7 +427,7 @@
void __iomem *ioremap_nocache_trace(unsigned long offset, unsigned long size)
{
void __iomem *p = ioremap_nocache(offset, size);
- printk(KERN_DEBUG MODULE_NAME ": ioremap_nocache(0x%lx, 0x%lx) = %p\n",
+ pr_debug(MODULE_NAME ": ioremap_nocache(0x%lx, 0x%lx) = %p\n",
offset, size, p);
ioremap_trace_core(offset, size, p);
return p;
@@ -455,7 +454,7 @@
};
struct remap_trace *trace;
struct remap_trace *tmp;
- printk(KERN_DEBUG MODULE_NAME ": Unmapping %p.\n", addr);
+ pr_debug(MODULE_NAME ": Unmapping %p.\n", addr);
record_timestamp(&event.header);
spin_lock(&trace_list_lock);
@@ -481,7 +480,7 @@
spin_lock(&trace_list_lock);
list_for_each_entry_safe(trace, tmp, &trace_list, list) {
- printk(KERN_WARNING MODULE_NAME ": purging non-iounmapped "
+ pr_warning(MODULE_NAME ": purging non-iounmapped "
"trace @0x%08lx, size 0x%lx.\n",
trace->probe.addr, trace->probe.len);
if (!nommiotrace)
@@ -500,39 +499,37 @@
dir = debugfs_create_dir(APP_DIR, NULL);
if (!dir) {
- printk(KERN_ERR MODULE_NAME
- ": Couldn't create relay app directory.\n");
+ pr_err(MODULE_NAME ": Couldn't create relay app directory.\n");
return -ENOMEM;
}
chan = create_channel(subbuf_size, n_subbufs);
if (!chan) {
debugfs_remove(dir);
- printk(KERN_ERR MODULE_NAME
- ": relay app channel creation failed\n");
+ pr_err(MODULE_NAME ": relay app channel creation failed\n");
return -ENOMEM;
}
- init_kmmio();
+ reference_kmmio();
proc_marker_file = create_proc_entry(MARKER_FILE, 0, NULL);
if (proc_marker_file)
proc_marker_file->write_proc = write_marker;
- printk(KERN_DEBUG MODULE_NAME ": loaded.\n");
+ pr_debug(MODULE_NAME ": loaded.\n");
if (nommiotrace)
- printk(KERN_DEBUG MODULE_NAME ": MMIO tracing disabled.\n");
+ pr_info(MODULE_NAME ": MMIO tracing disabled.\n");
if (ISA_trace)
- printk(KERN_WARNING MODULE_NAME
- ": Warning! low ISA range will be traced.\n");
+ pr_warning(MODULE_NAME ": Warning! low ISA range will be "
+ "traced.\n");
return 0;
}
static void __exit cleanup(void)
{
- printk(KERN_DEBUG MODULE_NAME ": unload...\n");
+ pr_debug(MODULE_NAME ": unload...\n");
clear_trace_list();
- cleanup_kmmio();
+ unreference_kmmio();
remove_proc_entry(MARKER_FILE, NULL);
destroy_channel();
if (dir)