Messages in this thread | | | Subject | Re: [PATCH v2] MIPS: Make check condition for SDBBP consistent with EJTAG spec | From | Tiezhu Yang <> | Date | Tue, 9 Feb 2021 21:09:52 +0800 |
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On 02/09/2021 08:11 PM, Thomas Bogendoerfer wrote: > On Tue, Feb 09, 2021 at 01:05:25PM +0800, Tiezhu Yang wrote: >> According to MIPS EJTAG Specification [1], a Debug Breakpoint >> exception occurs when an SDBBP instruction is executed, the >> CP0_DEBUG bit DBp indicates that a Debug Breakpoint exception >> occurred, just check bit DBp for SDBBP is more accurate. >> >> [1] http://www.t-es-t.hu/download/mips/md00047f.pdf >> >> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> >> --- >> >> v2: add MIPS_DEBUG_DBP definition >> >> arch/mips/include/asm/mipsregs.h | 4 ++++ >> arch/mips/kernel/genex.S | 4 ++-- >> 2 files changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h >> index a0e8ae5..9c8099a 100644 >> --- a/arch/mips/include/asm/mipsregs.h >> +++ b/arch/mips/include/asm/mipsregs.h >> @@ -1085,6 +1085,10 @@ >> #define CVMVMCONF_RMMUSIZEM1_S 0 >> #define CVMVMCONF_RMMUSIZEM1 (_U64CAST_(0xff) << CVMVMCONF_RMMUSIZEM1_S) >> >> +/* Debug register field definitions */ >> +#define MIPS_DEBUG_DBP_SHIFT 1 >> +#define MIPS_DEBUG_DBP (_ULCAST_(1) << MIPS_DEBUG_DBP_SHIFT) >> + >> /* >> * Coprocessor 1 (FPU) register names >> */ >> diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S >> index bcce32a..743d759 100644 >> --- a/arch/mips/kernel/genex.S >> +++ b/arch/mips/kernel/genex.S >> @@ -349,8 +349,8 @@ NESTED(ejtag_debug_handler, PT_SIZE, sp) >> MTC0 k0, CP0_DESAVE >> mfc0 k0, CP0_DEBUG >> >> - sll k0, k0, 30 # Check for SDBBP. >> - bgez k0, ejtag_return >> + andi k0, k0, MIPS_DEBUG_DBP # Check for SDBBP. >> + beqz k0, ejtag_return > IMHO both implementations are doing the same thing.
When I read the original code, it looks a little confusing at first glance, the initial aim of this patch is to make the code more readable and easier to understand.
> > Thomas. >
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