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Commit bd8ac686 authored by Pekka Paalanen's avatar Pekka Paalanen Committed by Thomas Gleixner
Browse files

ftrace: mmiotrace, updates 



here is a patch that makes mmiotrace work almost well within the tracing
framework. The patch applies on top of my previous patch. I have my own
output formatting in place now.

Summary of changes:
- fix the NULL dereference that was due to not calling tracing_reset()
- add print_line() callback into struct tracer
- implement print_line() for mmiotrace, producing up-to-spec text
- add my output header, but that is not really called in the right place
- rewrote the main structs in mmiotrace
- added two new trace entry types: TRACE_MMIO_RW and TRACE_MMIO_MAP
- made some functions in trace.c non-static
- check current==NULL in tracing_generic_entry_update()
- fix(?) comparison in trace_seq_printf()

Things seem to work fine except a few issues. Markers (text lines injected
into mmiotrace log) are missing, I did not feel hacking them in before we
have variable length entries. My output header is printed only for 'trace'
file, but not 'trace_pipe'. For some reason, despite my quick fix,
iter->trace is NULL in print_trace_line() when called from 'trace_pipe'
file, which means I don't get proper output formatting.

I only tried by loading nouveau.ko, which just detects the card, and that
is traced fine. I didn't try further. Map, two reads and unmap. Works
perfectly.

I am missing the information about overflows, I'd prefer to have a
counter for lost events. I didn't try, but I guess currently there is no
way of knowning when it overflows?

So, not too far from being fully operational, it seems :-)
And looking at the diffstat, there also is some 700-900 lines of user space
code that just became obsolete.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent f984b51e

arch/x86/Kconfig.debug

+1 −1
Original line number Diff line number Diff line
@@ -173,7 +173,7 @@ config MMIOTRACE_HOOKS 


config MMIOTRACE

	bool "Memory mapped IO tracing"

	depends on DEBUG_KERNEL && RELAY

	depends on DEBUG_KERNEL

	select TRACING

	select MMIOTRACE_HOOKS

	default y

arch/x86/kernel/mmiotrace/mmio-mod.c

+41 −99
Original line number Diff line number Diff line
@@ -37,11 +37,6 @@ 


#define 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;

	unsigned long ip;
@@ -56,18 +51,15 @@ struct remap_trace { 
	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);

static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace);



#if 0 /* XXX: no way gather this info anymore */

/* Access to this is not per-cpu. */

static DEFINE_PER_CPU(atomic_t, dropped);

#endif



static struct dentry *dir;

static struct dentry *marker_file;



static DEFINE_MUTEX(mmiotrace_mutex);
@@ -82,24 +74,21 @@ static LIST_HEAD(trace_list); /* struct remap_trace */ 
 *   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.

 * - is_enabled() guarantees that mmio_trace_record is allowed.

 * - 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;



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_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.");
@@ -110,6 +99,7 @@ static bool is_enabled(void) 
	return atomic_read(&mmiotrace_enabled);

}



#if 0 /* XXX: needs rewrite */

/*

 * Write callback for the debugfs entry:

 * Read a marker and write it to the mmio trace log
@@ -145,6 +135,7 @@ static ssize_t write_marker(struct file *file, const char __user *buffer, 
	kfree(event);

	return len;

}

#endif



static void print_pte(unsigned long address)

{
@@ -198,9 +189,10 @@ static void pre(struct kmmio_probe *p, struct pt_regs *regs, 
						unsigned long addr)

{

	struct trap_reason *my_reason = &get_cpu_var(pf_reason);

	struct mm_io_header_rw *my_trace = &get_cpu_var(cpu_trace);

	struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);

	const unsigned long instptr = instruction_pointer(regs);

	const enum reason_type type = get_ins_type(instptr);

	struct remap_trace *trace = p->user_data;



	/* it doesn't make sense to have more than one active trace per cpu */

	if (my_reason->active_traces)
@@ -212,23 +204,17 @@ static void pre(struct kmmio_probe *p, struct pt_regs *regs, 
	my_reason->addr = addr;

	my_reason->ip = instptr;



	my_trace->header.type = MMIO_MAGIC;

	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;

	 */

	my_trace->phys = addr - trace->probe.addr + trace->phys;

	my_trace->map_id = trace->id;



	/*

	 * Only record the program counter when requested.

	 * It may taint clean-room reverse engineering.

	 */

	if (trace_pc)

		my_trace->rw.pc = instptr;

		my_trace->pc = instptr;

	else

		my_trace->rw.pc = 0;

		my_trace->pc = 0;



	/*

	 * XXX: the timestamp recorded will be *after* the tracing has been
@@ -238,28 +224,25 @@ static void pre(struct kmmio_probe *p, struct pt_regs *regs, 


	switch (type) {

	case REG_READ:

		my_trace->header.type |=

			(MMIO_READ << MMIO_OPCODE_SHIFT) |

			(get_ins_mem_width(instptr) << MMIO_WIDTH_SHIFT);

		my_trace->opcode = MMIO_READ;

		my_trace->width = get_ins_mem_width(instptr);

		break;

	case REG_WRITE:

		my_trace->header.type |=

			(MMIO_WRITE << MMIO_OPCODE_SHIFT) |

			(get_ins_mem_width(instptr) << MMIO_WIDTH_SHIFT);

		my_trace->rw.value = get_ins_reg_val(instptr, regs);

		my_trace->opcode = MMIO_WRITE;

		my_trace->width = get_ins_mem_width(instptr);

		my_trace->value = get_ins_reg_val(instptr, regs);

		break;

	case IMM_WRITE:

		my_trace->header.type |=

			(MMIO_WRITE << MMIO_OPCODE_SHIFT) |

			(get_ins_mem_width(instptr) << MMIO_WIDTH_SHIFT);

		my_trace->rw.value = get_ins_imm_val(instptr);

		my_trace->opcode = MMIO_WRITE;

		my_trace->width = get_ins_mem_width(instptr);

		my_trace->value = get_ins_imm_val(instptr);

		break;

	default:

		{

			unsigned char *ip = (unsigned char *)instptr;

			my_trace->header.type |=

					(MMIO_UNKNOWN_OP << MMIO_OPCODE_SHIFT);

			my_trace->rw.value = (*ip) << 16 | *(ip + 1) << 8 |

			my_trace->opcode = MMIO_UNKNOWN_OP;

			my_trace->width = 0;

			my_trace->value = (*ip) << 16 | *(ip + 1) << 8 |

								*(ip + 2);

		}

	}
@@ -271,7 +254,7 @@ static void post(struct kmmio_probe *p, unsigned long condition, 
							struct pt_regs *regs)

{

	struct trap_reason *my_reason = &get_cpu_var(pf_reason);

	struct mm_io_header_rw *my_trace = &get_cpu_var(cpu_trace);

	struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);



	/* this should always return the active_trace count to 0 */

	my_reason->active_traces--;
@@ -282,20 +265,13 @@ static void post(struct kmmio_probe *p, unsigned long condition, 


	switch (my_reason->type) {

	case REG_READ:

		my_trace->rw.value = get_ins_reg_val(my_reason->ip, regs);

		my_trace->value = get_ins_reg_val(my_reason->ip, regs);

		break;

	default:

		break;

	}



	/*

	 * XXX: Several required values are ignored:

	 * - mapping id

	 * - program counter

	 * Also the address should be physical, not virtual.

	 */

	mmio_trace_record(my_trace->header.type, my_trace->rw.address,

							my_trace->rw.value);

	mmio_trace_rw(my_trace);

	put_cpu_var(cpu_trace);

	put_cpu_var(pf_reason);

}
@@ -305,21 +281,11 @@ static void ioremap_trace_core(unsigned long offset, unsigned long size, 
{

	static atomic_t next_id;

	struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);

	struct mm_io_header_map event = {

		.header = {

			.type = MMIO_MAGIC |

					(MMIO_PROBE << MMIO_OPCODE_SHIFT),

			.sec = 0,

			.nsec = 0,

			.pid = 0,

			.data_len = sizeof(struct mm_io_map)

		},

		.map = {

	struct mmiotrace_map map = {

		.phys = offset,

			.addr = (unsigned long)addr,

		.virt = (unsigned long)addr,

		.len = size,

			.pc   = 0

		}

		.opcode = MMIO_PROBE

	};



	if (!trace) {
@@ -338,15 +304,13 @@ static void ioremap_trace_core(unsigned long offset, unsigned long size, 
		.phys = offset,

		.id = atomic_inc_return(&next_id)

	};

	map.map_id = trace->id;



	spin_lock_irq(&trace_lock);

	if (!is_enabled())

		goto not_enabled;



	/*

	 * XXX: Insufficient data recorded!

	 */

	mmio_trace_record(event.header.type, event.map.addr, event.map.len);

	mmio_trace_mapping(&map);

	list_add_tail(&trace->list, &trace_list);

	if (!nommiotrace)

		register_kmmio_probe(&trace->probe);
@@ -369,21 +333,11 @@ mmiotrace_ioremap(unsigned long offset, unsigned long size, void __iomem *addr) 


static void iounmap_trace_core(volatile void __iomem *addr)

{

	struct mm_io_header_map event = {

		.header = {

			.type = MMIO_MAGIC |

				(MMIO_UNPROBE << MMIO_OPCODE_SHIFT),

			.sec = 0,

			.nsec = 0,

			.pid = 0,

			.data_len = sizeof(struct mm_io_map)

		},

		.map = {

	struct mmiotrace_map map = {

		.phys = 0,

			.addr = (unsigned long)addr,

		.virt = (unsigned long)addr,

		.len = 0,

			.pc   = 0

		}

		.opcode = MMIO_UNPROBE

	};

	struct remap_trace *trace;

	struct remap_trace *tmp;
@@ -404,8 +358,8 @@ static void iounmap_trace_core(volatile void __iomem *addr) 
			break;

		}

	}

	mmio_trace_record(event.header.type, event.map.addr,

					found_trace ? found_trace->id : -1);

	map.map_id = (found_trace) ? found_trace->id : -1;

	mmio_trace_mapping(&map);



not_enabled:

	spin_unlock_irq(&trace_lock);
@@ -448,10 +402,12 @@ static void clear_trace_list(void) 
	}

}



#if 0 /* XXX: out of order */

static struct file_operations fops_marker = {

	.owner =	THIS_MODULE,

	.write =	write_marker

};

#endif



void enable_mmiotrace(void)

{
@@ -464,9 +420,9 @@ void enable_mmiotrace(void) 
#if 0 /* XXX: tracing does not support text entries */

	marker_file = debugfs_create_file("marker", 0660, dir, NULL,

								&fops_marker);

#endif

	if (!marker_file)

		pr_err(NAME "marker file creation failed.\n");

#endif



	if (nommiotrace)

		pr_info(NAME "MMIO tracing disabled.\n");
@@ -502,17 +458,3 @@ void disable_mmiotrace(void) 
out:

	mutex_unlock(&mmiotrace_mutex);

}
 


int __init init_mmiotrace(void)

{

	pr_debug(NAME "load...\n");

	if (n_subbufs < 2)

		return -EINVAL;



	dir = debugfs_create_dir(APP_DIR, NULL);

	if (!dir) {

		pr_err(NAME "Couldn't create relay app directory.\n");

		return -ENOMEM;

	}

	return 0;

}

include/linux/mmiotrace.h

+25 −60
Original line number Diff line number Diff line
@@ -54,73 +54,38 @@ static inline void mmiotrace_iounmap(volatile void __iomem *addr) 
}

#endif /* CONFIG_MMIOTRACE_HOOKS */



/* in kernel/trace/trace_mmiotrace.c */

extern int __init init_mmiotrace(void);

extern void enable_mmiotrace(void);

extern void disable_mmiotrace(void);

extern void mmio_trace_record(u32 type, unsigned long addr, unsigned long arg);



#endif /* __KERNEL__ */





/*

 * If you change anything here, you must bump MMIO_VERSION.

 * This is the relay data format for user space.

 */

#define MMIO_VERSION 0x04



/* mm_io_header.type */

#define MMIO_OPCODE_MASK 0xff

#define MMIO_OPCODE_SHIFT 0

#define MMIO_WIDTH_MASK 0xff00

#define MMIO_WIDTH_SHIFT 8

#define MMIO_MAGIC (0x6f000000 | (MMIO_VERSION<<16))

#define MMIO_MAGIC_MASK 0xffff0000



enum mm_io_opcode {          /* payload type: */

	MMIO_READ = 0x1,     /* struct mm_io_rw */

	MMIO_WRITE = 0x2,    /* struct mm_io_rw */

	MMIO_PROBE = 0x3,    /* struct mm_io_map */

	MMIO_UNPROBE = 0x4,  /* struct mm_io_map */

enum mm_io_opcode {

	MMIO_READ = 0x1,     /* struct mmiotrace_rw */

	MMIO_WRITE = 0x2,    /* struct mmiotrace_rw */

	MMIO_PROBE = 0x3,    /* struct mmiotrace_map */

	MMIO_UNPROBE = 0x4,  /* struct mmiotrace_map */

	MMIO_MARKER = 0x5,   /* raw char data */

	MMIO_UNKNOWN_OP = 0x6, /* struct mm_io_rw */

	MMIO_UNKNOWN_OP = 0x6, /* struct mmiotrace_rw */

};



struct mm_io_header {

	__u32 type;     /* see MMIO_* macros above */

	__u32 sec;      /* timestamp */

	__u32 nsec;

	__u32 pid;      /* PID of the process, or 0 for kernel core */

	__u16 data_len; /* length of the following payload */

struct mmiotrace_rw {

	unsigned long phys;	/* PCI address of register */

	unsigned long value;

	unsigned long pc;	/* optional program counter */

	int map_id;

	unsigned char opcode;	/* one of MMIO_{READ,WRITE,UNKNOWN_OP} */

	unsigned char width;	/* size of register access in bytes */

};



struct mm_io_rw {

	__u64 address; /* virtual address of register */

	__u64 value;

	__u64 pc;      /* optional program counter */

struct mmiotrace_map {

	unsigned long phys;	/* base address in PCI space */

	unsigned long virt;	/* base virtual address */

	unsigned long len;	/* mapping size */

	int map_id;

	unsigned char opcode;	/* MMIO_PROBE or MMIO_UNPROBE */

};



struct mm_io_map {

	__u64 phys;  /* base address in PCI space */

	__u64 addr;  /* base virtual address */

	__u64 len;   /* mapping size */

	__u64 pc;    /* optional program counter */

};





/*

 * These structures are used to allow a single relay_write()

 * call to write a full packet.

 */



struct mm_io_header_rw {

	struct mm_io_header header;

	struct mm_io_rw rw;

} __attribute__((packed));

/* in kernel/trace/trace_mmiotrace.c */

extern void enable_mmiotrace(void);

extern void disable_mmiotrace(void);

extern void mmio_trace_rw(struct mmiotrace_rw *rw);

extern void mmio_trace_mapping(struct mmiotrace_map *map);



struct mm_io_header_map {

	struct mm_io_header header;

	struct mm_io_map map;

} __attribute__((packed));

#endif /* __KERNEL__ */



#endif /* MMIOTRACE_H */

kernel/trace/trace.c

+34 −0
Original line number Diff line number Diff line
@@ -831,6 +831,40 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data, 
		trace_function(tr, data, ip, parent_ip, flags);

}



#ifdef CONFIG_MMIOTRACE

void __trace_mmiotrace_rw(struct trace_array *tr, struct trace_array_cpu *data,

						struct mmiotrace_rw *rw)

{

	struct trace_entry *entry;

	unsigned long irq_flags;



	spin_lock_irqsave(&data->lock, irq_flags);

	entry			= tracing_get_trace_entry(tr, data);

	tracing_generic_entry_update(entry, 0);

	entry->type		= TRACE_MMIO_RW;

	entry->mmiorw		= *rw;

	spin_unlock_irqrestore(&data->lock, irq_flags);



	trace_wake_up();

}



void __trace_mmiotrace_map(struct trace_array *tr, struct trace_array_cpu *data,

						struct mmiotrace_map *map)

{

	struct trace_entry *entry;

	unsigned long irq_flags;



	spin_lock_irqsave(&data->lock, irq_flags);

	entry			= tracing_get_trace_entry(tr, data);

	tracing_generic_entry_update(entry, 0);

	entry->type		= TRACE_MMIO_MAP;

	entry->mmiomap		= *map;

	spin_unlock_irqrestore(&data->lock, irq_flags);



	trace_wake_up();

}

#endif



void __trace_stack(struct trace_array *tr,

		   struct trace_array_cpu *data,

		   unsigned long flags,

kernel/trace/trace.h

+14 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#include <asm/atomic.h>

#include <linux/sched.h>

#include <linux/clocksource.h>

#include <linux/mmiotrace.h>



enum trace_type {

	__TRACE_FIRST_TYPE = 0,
@@ -14,6 +15,8 @@ enum trace_type { 
	TRACE_WAKE,

	TRACE_STACK,

	TRACE_SPECIAL,

	TRACE_MMIO_RW,

	TRACE_MMIO_MAP,



	__TRACE_LAST_TYPE

};
@@ -75,6 +78,8 @@ struct trace_entry { 
		struct ctx_switch_entry		ctx;

		struct special_entry		special;

		struct stack_entry		stack;

		struct mmiotrace_rw		mmiorw;

		struct mmiotrace_map		mmiomap;

	};

};
@@ -255,6 +260,15 @@ extern unsigned long ftrace_update_tot_cnt; 
extern int DYN_FTRACE_TEST_NAME(void);

#endif



#ifdef CONFIG_MMIOTRACE

extern void __trace_mmiotrace_rw(struct trace_array *tr,

				struct trace_array_cpu *data,

				struct mmiotrace_rw *rw);

extern void __trace_mmiotrace_map(struct trace_array *tr,

				struct trace_array_cpu *data,

				struct mmiotrace_map *map);

#endif



#ifdef CONFIG_FTRACE_STARTUP_TEST

#ifdef CONFIG_FTRACE

extern int trace_selftest_startup_function(struct tracer *trace,