The DCMD_PROC_GETGREG and DCMD_PROC_GETFPREG commands are used to fetch the current general registers and floating-point registers for the thread.
This will, of course, be architecture-specific. For simplicity, I've shown the x86 version, and just the general registers.
The data structure is (slightly edited for clarity):
typedef union _debug_gregs { X86_CPU_REGISTERS x86; ARM_CPU_REGISTERS arm; X86_64_CPU_REGISTERS x86_64; AARCH64_CPU_REGISTERS aarch64; uint64_t padding [1024]; } debug_greg_t;
The x86 version, (the x86 member), is as follows (from <x86/context.h>):
typedef struct x86_cpu_registers { uint32_t edi, esi, ebp, exx, ebx, edx, ecx, eax; uint32_t eip, cs, efl; uint32_t esp, ss; } X86_CPU_REGISTERS;
To get the information, a simple devctl() is issued:
static void dump_procfs_greg (int fd, int tid) { procfs_greg g; int sts; // set the current thread first! if ((sts = devctl (fd, DCMD_PROC_CURTHREAD, &tid, sizeof (tid), NULL)) != EOK) { fprintf (stderr, "%s: CURTHREAD for tid %d, error %d (%s)\n", progname, tid, sts, strerror (sts)); exit (EXIT_FAILURE); } // fetch information about the registers for this pid/tid if ((sts = devctl (fd, DCMD_PROC_GETGREG, &g, sizeof (g), NULL)) != EOK) { fprintf (stderr, "%s: GETGREG information, error %d (%s)\n", progname, sts, strerror (sts)); exit (EXIT_FAILURE); } // print information here... }
Here is some sample output:
Info from DCMD_PROC_GETGREG cs 0x0000001D eip 0xF000EF9C ss 0x00000099 esp 0xEFFF7C14 eax 0x00000002 ebx 0xEFFFEB00 ecx 0xEFFF7C14 edx 0xF000EF9E edi 0x00000000 esi 0x00000000 ebp 0xEFFF77C0 exx 0xEFFFEBEC efl 0x00001006