mirror of
https://github.com/cirosantilli/linux-kernel-module-cheat.git
synced 2026-01-13 20:12:26 +00:00
73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
/* https://cirosantilli.com/linux-kernel-module-cheat#arm-pmccntr-register */
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#include <linux/debugfs.h>
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#include <linux/errno.h> /* EFAULT */
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/printk.h> /* pr_info */
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#include <linux/seq_file.h> /* seq_read, seq_lseek, single_release */
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#include <linux/uaccess.h> /* copy_from_user, copy_to_user */
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#include <uapi/linux/stat.h> /* S_IRUSR */
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static struct dentry *debugfs_file;
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static int show(struct seq_file *m, void *v)
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{
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u32 pmccntr;
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#if defined(__arm__)
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/* Invalid aarch64 asm. */
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/* TODO Internal error: Oops - undefined instruction: 0 [#1] ARM */
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/* Enable userland access to conter. */
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/* PMUSERENR = 1 */
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/*__asm__ __volatile__ ("mcr p15, 0, %0, c9, c14, 0" :: "r"(1));*/
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/* TODO oops undefined instruction. */
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/* PMCR.E (bit 0) = 1 */
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/*__asm__ __volatile__ ("mcr p15, 0, %0, c9, c12, 0" :: "r"(1));*/
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/* TODO oops undefined instruction. */
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/* Enable counter. */
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/* PMCNTENSET.C (bit 31) = 1 */
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/*__asm__ __volatile__ ("mcr p15, 0, %0, c9, c12, 1" :: "r"(1 << 31));*/
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/* Get counter value. */
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__asm__ __volatile__ ("mrc p15, 0, %0, c15, c12, 1" : "=r" (pmccntr));
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#else
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pmccntr = 0;
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#endif
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seq_printf(m, "%8.8llX\n", (unsigned long long)pmccntr);
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return 0;
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}
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static int open(struct inode *inode, struct file *file)
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{
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return single_open(file, show, NULL);
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}
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static const struct file_operations fops = {
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.llseek = seq_lseek,
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.open = open,
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.owner = THIS_MODULE,
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.read = seq_read,
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.release = single_release,
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};
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static int myinit(void)
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{
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debugfs_file = debugfs_create_file("lkmc_pmccntr", S_IRUSR, NULL, NULL, &fops);
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if (!debugfs_file) {
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return -1;
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}
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return 0;
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}
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static void myexit(void)
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{
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debugfs_remove(debugfs_file);
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}
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module_init(myinit)
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module_exit(myexit)
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MODULE_LICENSE("GPL");
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