| Message ID | 1612847125-3141-1-git-send-email-yangtiezhu@loongson.cn (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | ee54d379fc9c490797aa71d25d0320b5af5924a1 |
| Headers | show |
| Series | [v2] MIPS: Make check condition for SDBBP consistent with EJTAG spec | expand |
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. Thomas.
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. >
On Tue, Feb 09, 2021 at 09:09:52PM +0800, Tiezhu Yang wrote: > 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. which your version is, but the description sounds like there is a semantic change somewhere (at least to me). So with a little bit rewording I'm fine with applying your patch. Thomas.
On Tue, 9 Feb 2021, Thomas Bogendoerfer wrote: > > > > 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. > > which your version is, but the description sounds like there is a semantic > change somewhere (at least to me). So with a little bit rewording I'm > fine with applying your patch. Why is it confusing? This is assembly and you're supposed to understand this stuff when looking into it. Don't fix what ain't broke! Maciej
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 #ifdef CONFIG_SMP 1: PTR_LA k0, ejtag_debug_buffer_spinlock
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(-)