Hello to the ARM experts,
I am relatively new to ARM hardware. Usually I use off the shelf systems (various Linux distros) to set up the BBB, as referent design.
Recently, I have started to dive more deep into the armv7 A8 programming model. And I found confusing areas (I have concrete questions to ask).
Namely, I would like to read the Secure Configuration Register:
http://infocenter.arm.com/help/topic/com.arm.doc.ddi0344k/DDI0344K_cortex_a8_r3p2_trm.pdf#page=133
To access the Secure Configuration Register, read or write CP15 with: MRC p15, 0, <Rd>, c1, c1, 0 ; Read Secure Configuration Register data MCR p15, 0, <Rd>, c1, c1, 0 ; Write Secure Configuration Register data
For this purpose, I wrote iny driver, which is presented here:
/* * cp15_spm.c - how to read in Secure Privileged Mode (SPM) Secure Configuration Register data */ #include <linux/module.h> /* Needed by all modules */ #include <linux/kernel.h> /* Needed for KERN_INFO */ #include <linux/init.h> /* Needed for the macros */ MODULE_LICENSE("GPL"); ///< The license type -- this affects available functionality MODULE_DESCRIPTION("An armv7 A8 test driver"); ///< The description -- see modinfo MODULE_VERSION("0.01"); ///< A version number to inform users static inline unsigned asm_get_cpsr(void) { unsigned long retval; __asm ("mrs r0, cpsr"); __asm ("bic r0, r0, #0x1f"); __asm ("orr r0, r0, #0x16"); __asm ("msr cpsr_c, r0"); __asm ("mrs r0, cpsr" : "=r"(retval) ); return retval; } static int read_SPM_registers(void) { unsigned int reg_value = 0; printk(KERN_INFO "------------------------------------------------\n"); asm volatile("mrs %0, cpsr" : "=r"(reg_value) ); printk(KERN_INFO "CPSR/R0 value is: 0x%08x\n", reg_value); printk(KERN_INFO "NEW CPSR/R0 value using asm_get_cpsr() is: 0x%08x\n", asm_get_cpsr()); #if 0 asm( "mrs r0, cpsr\n\t" "bic r0, r0, #0x1f\n\t" "orr r0, r0, #0x16\n\t" "msr cpsr_c, r0\n\t" ); asm volatile("mrs %0, cpsr" : "=r"(reg_value) ); printk(KERN_INFO "NEW CPSR/R0 value using inline_asm is: 0x%08x\n", reg_value); #endif printk(KERN_INFO "------------------------------------------------\n"); asm volatile("mrc p15, 0, %0, c1, c1, 0" : "=r"(reg_value) ); printk(KERN_INFO "Secure Configuration Register data: 0x%08x\n", reg_value); // asm volatile("mrc p15, 0, %0, c1, c1, 1" : "=r"(reg_value) ); // printk(KERN_INFO "Secure Debug Enable Register: 0x%08x\n", reg_value); printk(KERN_INFO "\n"); return 0; } static int __init cp15_spm_init(void) { printk(KERN_INFO "cp15_Test init\n"); return read_SPM_registers(); } static void __exit cp15_spm_exit(void) { read_SPM_registers(); printk(KERN_INFO "cp15_Test exit\n"); } module_init(cp15_spm_init); module_exit(cp15_spm_exit);
While reading the first time CPSR register, I got the following value: 0x60000013 (b10011 Supervisor Mode) - I am root/superuser.
I tried to set CPSR mode (LSB 5 bits) to the b10110 Secure Monitor Mode, but it seems that with the above presented code I am NOT able to do that!
While executing the following code:
asm volatile("mrc p15, 0, %0, c1, c1, 0" : "=r"(reg_value) ); printk(KERN_INFO "Secure Configuration Register data: 0x%08x\n", reg_value);
I've got the following: Internal error: Oops - undefined instruction: 0 [#1] ARM
The full log from code execution is here:
root@beaglebone:~/projects/LKM# insmod cp15_spm.ko [22948.622390] cp15_Test init [22948.625381] ------------------------------------------------ [22948.631303] CPSR/R0 value is: 0x60000013 [22948.635480] NEW CPSR/R0 value using asm_get_cpsr() is: 0xc0b1b014 [22948.641850] ------------------------------------------------ [22948.647822] Internal error: Oops - undefined instruction: 0 [#1] ARM [22948.654463] Modules linked in: cp15_spm(O+) tilcdc backlight tda998x drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm drm_panel_orientation_quirks cfbfillrect cfbimgblt cfbcopyarea fb font [last unloaded: cp15_spm] [22948.675841] CPU: 0 PID: 11611 Comm: insmod Tainted: G O 5.0.15-jumpnow #1 [22948.684290] Hardware name: Generic AM33XX (Flattened Device Tree) [22948.690670] PC is at read_SPM_registers+0x40/0x70 [cp15_spm] [22948.696583] LR is at read_SPM_registers+0x40/0x70 [cp15_spm] [22948.702492] pc : [<bf18f040>] lr : [<bf18f040>] psr: 60000013 [22948.709036] sp : de23ddb8 ip : 00000000 fp : c0b0b088 [22948.714491] r10: de088dd8 r9 : 00000000 r8 : 00000000 [22948.719947] r7 : c0b6c6a8 r6 : bf194000 r5 : c0b0b088 r4 : bf190054 [22948.726763] r3 : 52a37879 r2 : 52a37879 r1 : c0b1b014 r0 : 00000030 [22948.733581] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none [22948.741033] Control: 10c5387d Table: 9cb70019 DAC: 00000051 [22948.747039] Process insmod (pid: 11611, stack limit = 0x58c41661) [22948.753401] Stack: (0xde23ddb8 to 0xde23e000) [22948.757953] dda0: c0b6cee0 c0102dc4 [22948.766498] ddc0: c01ff024 c0169f64 de000080 006000c0 ffffe000 00000000 60000013 0000000c [22948.775044] dde0: c019ee20 c0165dd8 c0b6c7b0 de000080 006000c0 c017df48 c0b6c7b0 c02440b0 [22948.783589] de00: 60000013 de7a4700 ffffe000 52a37879 bf191000 bf191000 bf191000 de69fcc0 [22948.792132] de20: de088d80 00000002 00000000 c019ee5c 00000002 c0165dd8 c0b6c730 c0b6c730 [22948.800678] de40: bf191000 c0b6d3f4 de088d80 c01a135c bf19100c 00007fff bf191000 c019e240 [22948.809223] de60: bf191048 c019d6b4 bf191214 00000000 bf191154 bf191170 c07047e0 c08b7e08 [22948.817766] de80: c085627c c0b0b088 00000000 c0855e84 00600001 00000000 c08cbc9c c08bfc80 [22948.826310] dea0: 00000000 00000000 00000000 00000000 00000000 00000000 6e72656b 00006c65 [22948.834855] dec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 [22948.843397] dee0: 00000000 00000000 00000000 00000000 00000000 52a37879 7fffffff c0b0b088 [22948.851941] df00: 00000000 00000003 004bfa68 c01011c4 de23c000 0000017b 00000000 c01a181c [22948.860486] df20: 7fffffff 00000000 00000003 c0163ec0 c0b0b088 e0edf000 0000ffb0 00000000 [22948.869031] df40: e0edf1b2 e0edf3c0 e0edf000 0000ffb0 e0eee880 e0eee690 e0eeb394 00003000 [22948.877575] df60: 00003100 00000000 00000000 00000000 0000157c 0000002b 0000002c 00000017 [22948.886121] df80: 00000015 00000013 00000000 52a37879 00000000 004d3150 00000000 beedfc58 [22948.894664] dfa0: 0000017b c0101000 004d3150 00000000 00000003 004bfa68 00000000 00000000 [22948.903209] dfc0: 004d3150 00000000 beedfc58 0000017b 00000002 00000000 beedfdd8 00000000 [22948.911754] dfe0: beedfc20 beedfc10 004b6b58 b6e810a0 60000010 00000003 00000000 00000000 [22948.920331] [<bf18f040>] (read_SPM_registers [cp15_spm]) from [<c0102dc4>] (do_one_initcall+0x60/0x230) [22948.930159] [<c0102dc4>] (do_one_initcall) from [<c019ee5c>] (do_init_module+0x64/0x214) [22948.938615] [<c019ee5c>] (do_init_module) from [<c01a135c>] (load_module+0x22e8/0x2544) [22948.946979] [<c01a135c>] (load_module) from [<c01a181c>] (sys_finit_module+0xc4/0xdc) [22948.955160] [<c01a181c>] (sys_finit_module) from [<c0101000>] (ret_fast_syscall+0x0/0x28) [22948.963700] Exception stack(0xde23dfa8 to 0xde23dff0) [22948.968977] dfa0: 004d3150 00000000 00000003 004bfa68 00000000 00000000 [22948.977519] dfc0: 004d3150 00000000 beedfc58 0000017b 00000002 00000000 beedfdd8 00000000 [22948.986060] dfe0: beedfc20 beedfc10 004b6b58 b6e810a0 [22948.991340] Code: e59f002c eb3f988d e1a00004 eb3f988b (ee111f11) [22948.997710] ---[ end trace b9732827550e3376 ]--- Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.647822] Internal error: Oops - undefined instruction: 0 [#1] ARM Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.747039] Process insmod (pid: 11611, stack limit = 0x58c41661) Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.753401] Stack: (0xde23ddb8 to 0xde23e000) Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.757953] dda0: c0b6cee0 c0102dc4 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.766498] ddc0: c01ff024 c0169f64 de000080 006000c0 ffffe000 00000000 60000013 0000000c Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.775044] dde0: c019ee20 c0165dd8 c0b6c7b0 de000080 006000c0 c017df48 c0b6c7b0 c02440b0 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.783589] de00: 60000013 de7a4700 ffffe000 52a37879 bf191000 bf191000 bf191000 de69fcc0 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.792132] de20: de088d80 00000002 00000000 c019ee5c 00000002 c0165dd8 c0b6c730 c0b6c730 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.800678] de40: bf191000 c0b6d3f4 de088d80 c01a135c bf19100c 00007fff bf191000 c019e240 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.809223] de60: bf191048 c019d6b4 bf191214 00000000 bf191154 bf191170 c07047e0 c08b7e08 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.817766] de80: c085627c c0b0b088 00000000 c0855e84 00600001 00000000 c08cbc9c c08bfc80 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.826310] dea0: 00000000 00000000 00000000 00000000 00000000 00000000 6e72656b 00006c65 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.834855] dec0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.843397] dee0: 00000000 00000000 00000000 00000000 00000000 52a37879 7fffffff c0b0b088 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.851941] df00: 00000000 00000003 004bfa68 c01011c4 de23c000 0000017b 00000000 c01a181c Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.860486] df20: 7fffffff 00000000 00000003 c0163ec0 c0b0b088 e0edf000 0000ffb0 00000000 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.869031] df40: e0edf1b2 e0edf3c0 e0edf000 0000ffb0 e0eee880 e0eee690 e0eeb394 00003000 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.877575] df60: 00003100 00000000 00000000 00000000 0000157c 0000002b 0000002c 00000017 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.886121] df80: 00000015 00000013 00000000 52a37879 00000000 004d3150 00000000 beedfc58 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.894664] dfa0: 0000017b c0101000 004d3150 00000000 00000003 004bfa68 00000000 00000000 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.903209] dfc0: 004d3150 00000000 beedfc58 0000017b 00000002 00000000 beedfdd8 00000000 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.911754] dfe0: beedfc20 beedfc10 004b6b58 b6e810a0 60000010 00000003 00000000 00000000 Broadcast message from systemd-journald@beaglebone (Thu 2019-06-13 18:51:58 UTC): kernel[1422]: [22948.991340] Code: e59f002c eb3f988d e1a00004 eb3f988b (ee111f11) Segmentation fault root@beaglebone:~/projects/LKM#
Could you, please, show me the code snippet which switches Supervisor Mode to Secure Monitor Mode (if at all possible)?
Thank you,
_nobody_
AFAIK, TI uses secure mode, so you are running in non-secure mode. Only a few SMCs are used.
This is correct. I run in non-secure mode: 0x13 which is Supervisor Mode. Can I switch somehow in Secure Monitor Mode, and how to do it (if possible)?
Does anybody know which modes are used in am3358 (TI sitara), and/or where I can find the Sitara am3358 documentation?
Thank you!