msm8909添加/system/bin/r用于读取寄存器

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底层支持
请检查 kernel 编译是否支持

Enable devmem/devkmem 
kernel\arch\arm64\configs\xxxxxxx_defconfig 
+ CONFIG_DEVMEM=y 
+ CONFIG_DEVKMEM=y 

由于平台上没有r.c
https://blog.csdn.net/mike8825/article/details/69790338
从这个老兄里copy了代码，集成到里面
制作bp文件，用于编译

Android.bp

// Copyright 2013 The Android Open Source Projectcc_binary {name: "r",srcs: ["r.c"],shared_libs: ["libcutils"],cflags: ["-Werror"],
}

r.c
在转载的文件中添加了
#define PAGE_SIZE 4096
r_main修改为main

#include <fcntl.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>#if __LP64__
#define strtoptr strtoull
#else
#define strtoptr strtoul
#endif
#define PAGE_SIZE 4096
static int usage()
{fprintf(stderr,"r [-b|-s] <address> [<value>]\n");return -1;
}int main(int argc, char *argv[])
{if(argc < 2) return usage();int width = 4;if(!strcmp(argv[1], "-b")) {width = 1;argc--;argv++;} else if(!strcmp(argv[1], "-s")) {width = 2;argc--;argv++;}if(argc < 2) return usage();uintptr_t addr = strtoptr(argv[1], 0, 16);uintptr_t endaddr = 0;char* end = strchr(argv[1], '-');if (end)endaddr = strtoptr(end + 1, 0, 16);if (!endaddr)endaddr = addr + width - 1;if (endaddr <= addr) {fprintf(stderr, "end address <= start address\n");return -1;}bool set = false;uint32_t value = 0;if(argc > 2) {set = true;value = strtoul(argv[2], 0, 16);}int fd = open("/dev/mem", O_RDWR | O_SYNC);if(fd < 0) {fprintf(stderr,"cannot open /dev/mem\n");return -1;}off64_t mmap_start = addr & ~(PAGE_SIZE - 1);size_t mmap_size = endaddr - mmap_start + 1;mmap_size = (mmap_size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);void* page = mmap64(0, mmap_size, PROT_READ | PROT_WRITE,MAP_SHARED, fd, mmap_start);if(page == MAP_FAILED){fprintf(stderr,"cannot mmap region\n");return -1;}while (addr <= endaddr) {switch(width){case 4: {uint32_t* x = (uint32_t*) (((uintptr_t) page) + (addr & 4095));if(set) *x = value;fprintf(stderr,"%08"PRIxPTR": %08x\n", addr, *x);break;}case 2: {uint16_t* x = (uint16_t*) (((uintptr_t) page) + (addr & 4095));if(set) *x = value;fprintf(stderr,"%08"PRIxPTR": %04x\n", addr, *x);break;}case 1: {uint8_t* x = (uint8_t*) (((uintptr_t) page) + (addr & 4095));if(set) *x = value;fprintf(stderr,"%08"PRIxPTR": %02x\n", addr, *x);break;}}addr += width;}return 0;
}

./system/core/shell_and_utilities/Android.bp
添加进编译

编译成功后就可以发现/system/bin/r中使用命令了

msm8909:/system/bin # /system/bin/r 0x0005E07C
0005e07c: xxxxx

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