diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/controllers/memory.txt | 14 | ||||
| -rw-r--r-- | Documentation/gpio.txt | 16 | ||||
| -rw-r--r-- | Documentation/kprobes.txt | 243 |
3 files changed, 26 insertions, 247 deletions
diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt index 6015347b41e..866b9cd9a95 100644 --- a/Documentation/controllers/memory.txt +++ b/Documentation/controllers/memory.txt @@ -1,4 +1,8 @@ -Memory Controller +Memory Resource Controller + +NOTE: The Memory Resource Controller has been generically been referred +to as the memory controller in this document. Do not confuse memory controller +used here with the memory controller that is used in hardware. Salient features @@ -152,7 +156,7 @@ The memory controller uses the following hierarchy a. Enable CONFIG_CGROUPS b. Enable CONFIG_RESOURCE_COUNTERS -c. Enable CONFIG_CGROUP_MEM_CONT +c. Enable CONFIG_CGROUP_MEM_RES_CTLR 1. Prepare the cgroups # mkdir -p /cgroups @@ -164,7 +168,7 @@ c. Enable CONFIG_CGROUP_MEM_CONT Since now we're in the 0 cgroup, We can alter the memory limit: -# echo -n 4M > /cgroups/0/memory.limit_in_bytes +# echo 4M > /cgroups/0/memory.limit_in_bytes NOTE: We can use a suffix (k, K, m, M, g or G) to indicate values in kilo, mega or gigabytes. @@ -185,7 +189,7 @@ number of factors, such as rounding up to page boundaries or the total availability of memory on the system. The user is required to re-read this file after a write to guarantee the value committed by the kernel. -# echo -n 1 > memory.limit_in_bytes +# echo 1 > memory.limit_in_bytes # cat memory.limit_in_bytes 4096 @@ -197,7 +201,7 @@ caches, RSS and Active pages/Inactive pages are shown. The memory.force_empty gives an interface to drop *all* charges by force. -# echo -n 1 > memory.force_empty +# echo 1 > memory.force_empty will drop all charges in cgroup. Currently, this is maintained for test. diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 8da724e2a0f..54630095aa3 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -2,6 +2,9 @@ GPIO Interfaces This provides an overview of GPIO access conventions on Linux. +These calls use the gpio_* naming prefix. No other calls should use that +prefix, or the related __gpio_* prefix. + What is a GPIO? =============== @@ -69,11 +72,13 @@ in this document, but drivers acting as clients to the GPIO interface must not care how it's implemented.) That said, if the convention is supported on their platform, drivers should -use it when possible. Platforms should declare GENERIC_GPIO support in -Kconfig (boolean true), which multi-platform drivers can depend on when -using the include file: +use it when possible. Platforms must declare GENERIC_GPIO support in their +Kconfig (boolean true), and provide an <asm/gpio.h> file. Drivers that can't +work without standard GPIO calls should have Kconfig entries which depend +on GENERIC_GPIO. The GPIO calls are available, either as "real code" or as +optimized-away stubs, when drivers use the include file: - #include <asm/gpio.h> + #include <linux/gpio.h> If you stick to this convention then it'll be easier for other developers to see what your code is doing, and help maintain it. @@ -316,6 +321,9 @@ pulldowns integrated on some platforms. Not all platforms support them, or support them in the same way; and any given board might use external pullups (or pulldowns) so that the on-chip ones should not be used. (When a circuit needs 5 kOhm, on-chip 100 kOhm resistors won't do.) +Likewise drive strength (2 mA vs 20 mA) and voltage (1.8V vs 3.3V) is a +platform-specific issue, as are models like (not) having a one-to-one +correspondence between configurable pins and GPIOs. There are other system-specific mechanisms that are not specified here, like the aforementioned options for input de-glitching and wire-OR output. diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 83f515c2905..be89f393274 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -192,7 +192,8 @@ code mapping. The Kprobes API includes a "register" function and an "unregister" function for each type of probe. Here are terse, mini-man-page specifications for these functions and the associated probe handlers -that you'll write. See the latter half of this document for examples. +that you'll write. See the files in the samples/kprobes/ sub-directory +for examples. 4.1 register_kprobe @@ -420,249 +421,15 @@ e. Watchpoint probes (which fire on data references). 8. Kprobes Example -Here's a sample kernel module showing the use of kprobes to dump a -stack trace and selected i386 registers when do_fork() is called. ------ cut here ----- -/*kprobe_example.c*/ -#include <linux/kernel.h> -#include <linux/module.h> -#include <linux/kprobes.h> -#include <linux/sched.h> - -/*For each probe you need to allocate a kprobe structure*/ -static struct kprobe kp; - -/*kprobe pre_handler: called just before the probed instruction is executed*/ -int handler_pre(struct kprobe *p, struct pt_regs *regs) -{ - printk("pre_handler: p->addr=0x%p, eip=%lx, eflags=0x%lx\n", - p->addr, regs->eip, regs->eflags); - dump_stack(); - return 0; -} - -/*kprobe post_handler: called after the probed instruction is executed*/ -void handler_post(struct kprobe *p, struct pt_regs *regs, unsigned long flags) -{ - printk("post_handler: p->addr=0x%p, eflags=0x%lx\n", - p->addr, regs->eflags); -} - -/* fault_handler: this is called if an exception is generated for any - * instruction within the pre- or post-handler, or when Kprobes - * single-steps the probed instruction. - */ -int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr) -{ - printk("fault_handler: p->addr=0x%p, trap #%dn", - p->addr, trapnr); - /* Return 0 because we don't handle the fault. */ - return 0; -} - -static int __init kprobe_init(void) -{ - int ret; - kp.pre_handler = handler_pre; - kp.post_handler = handler_post; - kp.fault_handler = handler_fault; - kp.symbol_name = "do_fork"; - - ret = register_kprobe(&kp); - if (ret < 0) { - printk("register_kprobe failed, returned %d\n", ret); - return ret; - } - printk("kprobe registered\n"); - return 0; -} - -static void __exit kprobe_exit(void) -{ - unregister_kprobe(&kp); - printk("kprobe unregistered\n"); -} - -module_init(kprobe_init) -module_exit(kprobe_exit) -MODULE_LICENSE("GPL"); ------ cut here ----- - -You can build the kernel module, kprobe-example.ko, using the following -Makefile: ------ cut here ----- -obj-m := kprobe-example.o -KDIR := /lib/modules/$(shell uname -r)/build -PWD := $(shell pwd) -default: - $(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules -clean: - rm -f *.mod.c *.ko *.o ------ cut here ----- - -$ make -$ su - -... -# insmod kprobe-example.ko - -You will see the trace data in /var/log/messages and on the console -whenever do_fork() is invoked to create a new process. +See samples/kprobes/kprobe_example.c 9. Jprobes Example -Here's a sample kernel module showing the use of jprobes to dump -the arguments of do_fork(). ------ cut here ----- -/*jprobe-example.c */ -#include <linux/kernel.h> -#include <linux/module.h> -#include <linux/fs.h> -#include <linux/uio.h> -#include <linux/kprobes.h> - -/* - * Jumper probe for do_fork. - * Mirror principle enables access to arguments of the probed routine - * from the probe handler. - */ - -/* Proxy routine having the same arguments as actual do_fork() routine */ -long jdo_fork(unsigned long clone_flags, unsigned long stack_start, - struct pt_regs *regs, unsigned long stack_size, - int __user * parent_tidptr, int __user * child_tidptr) -{ - printk("jprobe: clone_flags=0x%lx, stack_size=0x%lx, regs=0x%p\n", - clone_flags, stack_size, regs); - /* Always end with a call to jprobe_return(). */ - jprobe_return(); - /*NOTREACHED*/ - return 0; -} - -static struct jprobe my_jprobe = { - .entry = jdo_fork -}; - -static int __init jprobe_init(void) -{ - int ret; - my_jprobe.kp.symbol_name = "do_fork"; - - if ((ret = register_jprobe(&my_jprobe)) <0) { - printk("register_jprobe failed, returned %d\n", ret); - return -1; - } - printk("Planted jprobe at %p, handler addr %p\n", - my_jprobe.kp.addr, my_jprobe.entry); - return 0; -} - -static void __exit jprobe_exit(void) -{ - unregister_jprobe(&my_jprobe); - printk("jprobe unregistered\n"); -} - -module_init(jprobe_init) -module_exit(jprobe_exit) -MODULE_LICENSE("GPL"); ------ cut here ----- - -Build and insert the kernel module as shown in the above kprobe -example. You will see the trace data in /var/log/messages and on -the console whenever do_fork() is invoked to create a new process. -(Some messages may be suppressed if syslogd is configured to -eliminate duplicate messages.) +See samples/kprobes/jprobe_example.c 10. Kretprobes Example -Here's a sample kernel module showing the use of return probes to -report failed calls to sys_open(). ------ cut here ----- -/*kretprobe-example.c*/ -#include <linux/kernel.h> -#include <linux/module.h> -#include <linux/kprobes.h> -#include <linux/ktime.h> - -/* per-instance private data */ -struct my_data { - ktime_t entry_stamp; -}; - -static const char *probed_func = "sys_open"; - -/* Timestamp function entry. */ -static int entry_handler(struct kretprobe_instance *ri, struct pt_regs *regs) -{ - struct my_data *data; - - if(!current->mm) - return 1; /* skip kernel threads */ - - data = (struct my_data *)ri->data; - data->entry_stamp = ktime_get(); - return 0; -} - -/* If the probed function failed, log the return value and duration. - * Duration may turn out to be zero consistently, depending upon the - * granularity of time accounting on the platform. */ -static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs) -{ - int retval = regs_return_value(regs); - struct my_data *data = (struct my_data *)ri->data; - s64 delta; - ktime_t now; - - if (retval < 0) { - now = ktime_get(); - delta = ktime_to_ns(ktime_sub(now, data->entry_stamp)); - printk("%s: return val = %d (duration = %lld ns)\n", - probed_func, retval, delta); - } - return 0; -} - -static struct kretprobe my_kretprobe = { - .handler = return_handler, - .entry_handler = entry_handler, - .data_size = sizeof(struct my_data), - .maxactive = 20, /* probe up to 20 instances concurrently */ -}; - -static int __init kretprobe_init(void) -{ - int ret; - my_kretprobe.kp.symbol_name = (char *)probed_func; - - if ((ret = register_kretprobe(&my_kretprobe)) < 0) { - printk("register_kretprobe failed, returned %d\n", ret); - return -1; - } - printk("Kretprobe active on %s\n", my_kretprobe.kp.symbol_name); - return 0; -} - -static void __exit kretprobe_exit(void) -{ - unregister_kretprobe(&my_kretprobe); - printk("kretprobe unregistered\n"); - /* nmissed > 0 suggests that maxactive was set too low. */ - printk("Missed probing %d instances of %s\n", - my_kretprobe.nmissed, probed_func); -} - -module_init(kretprobe_init) -module_exit(kretprobe_exit) -MODULE_LICENSE("GPL"); ------ cut here ----- - -Build and insert the kernel module as shown in the above kprobe -example. You will see the trace data in /var/log/messages and on the -console whenever sys_open() returns a negative value. (Some messages -may be suppressed if syslogd is configured to eliminate duplicate -messages.) +See samples/kprobes/kretprobe_example.c For additional information on Kprobes, refer to the following URLs: http://www-106.ibm.com/developerworks/library/l-kprobes.html?ca=dgr-lnxw42Kprobe |