microblaze: Add KGDB support
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From: Jason Wessel on 28 Jul 2010 08:00 On 07/28/2010 04:29 AM, Michal Simek wrote: > Kgdb uses brki r16, 0x18 instruction to call > low level _debug_exception function which save > current state to pt_regs and call microblaze_kgdb_break > function. _debug_exception should be called only from > the kernel space. User space calling is not supported > because user application debugging uses different handling. > > pt_regs_to_gdb_regs loads additional special registers > which can't be changed > > * Enable KGDB in Kconfig > * Remove ancient not-tested KGDB support > * Remove ancient _debug_exception code from entry.S > > Only MMU KGDB support is supported. > > There is only one place I saw a problem and if you fix it, you can add: Acked-by: Jason Wessel <jason.wessel(a)windriver.com> > + > +int kgdb_arch_handle_exception(int vector, int signo, int err_code, > + char *remcom_in_buffer, char *remcom_out_buffer, > + struct pt_regs *regs) > +{ > + char *ptr; > + unsigned long address; > + int cpu = smp_processor_id(); > + > + switch (remcom_in_buffer[0]) { > + case 's': > + case 'c': > + /* handle the optional parameter */ > + ptr = &remcom_in_buffer[1]; > + if (kgdb_hex2long(&ptr, &address)) > + regs->pc = address; > + atomic_set(&kgdb_cpu_doing_single_step, -1); > + if (remcom_in_buffer[0] == 's') > + atomic_set(&kgdb_cpu_doing_single_step, cpu); > + > + return 0; > + } > As far as I can see there is no code in the arch specific portion to make use of single stepping. It needs to be implemented using hardware assist, or a software breakpoint strategy, else you simply omit the 's' case from statement so that kdb will not enable single stepping at run time. Example: switch (remcom_in_buffer[0]) { case 'c': /* handle the optional parameter */ ptr = &remcom_in_buffer[1]; if (kgdb_hex2long(&ptr, &address)) regs->pc = address; return 0; } You can also remove the kgdb_cpu_doing_single_step operations because this arch does not currently implement the kgdb single stepping. Cheers, Jason. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Michal Simek on 28 Jul 2010 08:10
Jason Wessel wrote: > On 07/28/2010 04:29 AM, Michal Simek wrote: >> Kgdb uses brki r16, 0x18 instruction to call >> low level _debug_exception function which save >> current state to pt_regs and call microblaze_kgdb_break >> function. _debug_exception should be called only from >> the kernel space. User space calling is not supported >> because user application debugging uses different handling. >> >> pt_regs_to_gdb_regs loads additional special registers >> which can't be changed >> >> * Enable KGDB in Kconfig >> * Remove ancient not-tested KGDB support >> * Remove ancient _debug_exception code from entry.S >> >> Only MMU KGDB support is supported. >> >> > There is only one place I saw a problem and if you fix it, you can add: > > Acked-by: Jason Wessel <jason.wessel(a)windriver.com> > >> + >> +int kgdb_arch_handle_exception(int vector, int signo, int err_code, >> + char *remcom_in_buffer, char *remcom_out_buffer, >> + struct pt_regs *regs) >> +{ >> + char *ptr; >> + unsigned long address; >> + int cpu = smp_processor_id(); >> + >> + switch (remcom_in_buffer[0]) { >> + case 's': >> + case 'c': >> + /* handle the optional parameter */ >> + ptr = &remcom_in_buffer[1]; >> + if (kgdb_hex2long(&ptr, &address)) >> + regs->pc = address; >> + atomic_set(&kgdb_cpu_doing_single_step, -1); >> + if (remcom_in_buffer[0] == 's') >> + atomic_set(&kgdb_cpu_doing_single_step, cpu); >> + >> + return 0; >> + } >> > > As far as I can see there is no code in the arch specific portion to > make use of single stepping. It needs to be implemented using hardware > assist, or a software breakpoint strategy, else you simply omit the 's' > case from statement so that kdb will not enable single stepping at run time. > > Example: > > switch (remcom_in_buffer[0]) { > case 'c': > /* handle the optional parameter */ > ptr = &remcom_in_buffer[1]; > if (kgdb_hex2long(&ptr, &address)) > regs->pc = address; > > return 0; > } > > > You can also remove the kgdb_cpu_doing_single_step operations because > this arch does not currently implement the kgdb single stepping. Ok. I will remove it. I copied this part of the code from somewhere. gdb handle single stepping and always send Z0 packet to the next instruction or two breakpoints for branches. Thanks, Michal > > > Cheers, > Jason. -- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/ Microblaze U-BOOT custodian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |