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Message-ID: <20191114182424.Horde.vUb7nGovT-Sg_Gzpih2Gsg3@messagerie.si.c-s.fr>
Date: Thu, 14 Nov 2019 18:24:24 +0100
From: Christophe Leroy <christophe.leroy@....fr>
To: Michael Ellerman <mpe@...erman.id.au>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
ravi.bangoria@...ux.ibm.com, Paul Mackerras <paulus@...ba.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH 2/2] powerpc/hw_breakpoints: Rewrite 8xx breakpoints to
allow any address range size.
Michael Ellerman <mpe@...erman.id.au> a écrit :
> Christophe Leroy <christophe.leroy@....fr> writes:
>> Unlike standard powerpc, Powerpc 8xx doesn't have SPRN_DABR, but
>> it has a breakpoint support based on a set of comparators which
>> allow more flexibility.
>>
>> Commit 4ad8622dc548 ("powerpc/8xx: Implement hw_breakpoint")
>> implemented breakpoints by emulating the DABR behaviour. It did
>> this by setting one comparator the match 4 bytes at breakpoint address
>> and the other comparator to match 4 bytes at breakpoint address + 4.
>>
>> Rewrite 8xx hw_breakpoint to make breakpoints match all addresses
>> defined by the breakpoint address and length by making full use of
>> comparators.
>>
>> Now, comparator E is set to match any address greater than breakpoint
>> address minus one. Comparator F is set to match any address lower than
>> breakpoint address plus breakpoint length.
>>
>> When the breakpoint range starts at address 0, the breakpoint is set
>> to match comparator F only. When the breakpoint range end at address
>> 0xffffffff, the breakpoint is set to match comparator E only.
>> Otherwise the breakpoint is set to match comparator E and F.
>>
>> At the same time, use registers bit names instead of hardcode values.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
>> Cc: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
>> ---
>> arch/powerpc/include/asm/reg_8xx.h | 14 ++++++++++
>> arch/powerpc/kernel/hw_breakpoint.c | 3 ++
>> arch/powerpc/kernel/process.c | 55
>> ++++++++++++++++++++++---------------
>> 3 files changed, 50 insertions(+), 22 deletions(-)
>
> I thought Ravi was going to pick this up in his series, but seems not.
> So now this no longer applies since I merged that series.
>
> Can one of you rebase and resend please?
I'm on holiday in the Alps for two weeks. Won't be able to do it
before 26th Nov.
Christophe
>
> cheers
>
>> diff --git a/arch/powerpc/include/asm/reg_8xx.h
>> b/arch/powerpc/include/asm/reg_8xx.h
>> index abc663c0f1db..98e97c22df8b 100644
>> --- a/arch/powerpc/include/asm/reg_8xx.h
>> +++ b/arch/powerpc/include/asm/reg_8xx.h
>> @@ -37,7 +37,21 @@
>> #define SPRN_CMPE 152
>> #define SPRN_CMPF 153
>> #define SPRN_LCTRL1 156
>> +#define LCTRL1_CTE_GT 0xc0000000
>> +#define LCTRL1_CTF_LT 0x14000000
>> +#define LCTRL1_CRWE_RW 0x00000000
>> +#define LCTRL1_CRWE_RO 0x00040000
>> +#define LCTRL1_CRWE_WO 0x000c0000
>> +#define LCTRL1_CRWF_RW 0x00000000
>> +#define LCTRL1_CRWF_RO 0x00010000
>> +#define LCTRL1_CRWF_WO 0x00030000
>> #define SPRN_LCTRL2 157
>> +#define LCTRL2_LW0EN 0x80000000
>> +#define LCTRL2_LW0LA_E 0x00000000
>> +#define LCTRL2_LW0LA_F 0x04000000
>> +#define LCTRL2_LW0LA_EandF 0x08000000
>> +#define LCTRL2_LW0LADC 0x02000000
>> +#define LCTRL2_SLW0EN 0x00000002
>> #ifdef CONFIG_PPC_8xx
>> #define SPRN_ICTRL 158
>> #endif
>> diff --git a/arch/powerpc/kernel/hw_breakpoint.c
>> b/arch/powerpc/kernel/hw_breakpoint.c
>> index 28ad3171bb82..d8bd4dbef561 100644
>> --- a/arch/powerpc/kernel/hw_breakpoint.c
>> +++ b/arch/powerpc/kernel/hw_breakpoint.c
>> @@ -163,6 +163,9 @@ int hw_breakpoint_arch_parse(struct perf_event *bp,
>> */
>> if (!ppc_breakpoint_available())
>> return -ENODEV;
>> + /* 8xx can setup a range without limitation */
>> + if (IS_ENABLED(CONFIG_PPC_8xx))
>> + return 0;
>> length_max = 8; /* DABR */
>> if (dawr_enabled()) {
>> length_max = 512 ; /* 64 doublewords */
>> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
>> index 8fc4de0d22b4..79e4f072a746 100644
>> --- a/arch/powerpc/kernel/process.c
>> +++ b/arch/powerpc/kernel/process.c
>> @@ -751,28 +751,6 @@ static inline int __set_dabr(unsigned long
>> dabr, unsigned long dabrx)
>> mtspr(SPRN_DABRX, dabrx);
>> return 0;
>> }
>> -#elif defined(CONFIG_PPC_8xx)
>> -static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
>> -{
>> - unsigned long addr = dabr & ~HW_BRK_TYPE_DABR;
>> - unsigned long lctrl1 = 0x90000000; /* compare type: equal on E & F */
>> - unsigned long lctrl2 = 0x8e000002; /* watchpoint 1 on cmp E | F */
>> -
>> - if ((dabr & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_READ)
>> - lctrl1 |= 0xa0000;
>> - else if ((dabr & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_WRITE)
>> - lctrl1 |= 0xf0000;
>> - else if ((dabr & HW_BRK_TYPE_RDWR) == 0)
>> - lctrl2 = 0;
>> -
>> - mtspr(SPRN_LCTRL2, 0);
>> - mtspr(SPRN_CMPE, addr);
>> - mtspr(SPRN_CMPF, addr + 4);
>> - mtspr(SPRN_LCTRL1, lctrl1);
>> - mtspr(SPRN_LCTRL2, lctrl2);
>> -
>> - return 0;
>> -}
>> #else
>> static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
>> {
>> @@ -793,6 +771,37 @@ static inline int set_dabr(struct
>> arch_hw_breakpoint *brk)
>> return __set_dabr(dabr, dabrx);
>> }
>>
>> +static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)
>> +{
>> + unsigned long lctrl1 = LCTRL1_CTE_GT | LCTRL1_CTF_LT | LCTRL1_CRWE_RW |
>> + LCTRL1_CRWF_RW;
>> + unsigned long lctrl2 = LCTRL2_LW0EN | LCTRL2_LW0LADC | LCTRL2_SLW0EN;
>> +
>> + if (brk->address == 0)
>> + lctrl2 |= LCTRL2_LW0LA_F;
>> + else if (brk->address + brk->len == 0)
>> + lctrl2 |= LCTRL2_LW0LA_E;
>> + else
>> + lctrl2 |= LCTRL2_LW0LA_EandF;
>> +
>> + mtspr(SPRN_LCTRL2, 0);
>> +
>> + if ((brk->type & HW_BRK_TYPE_RDWR) == 0)
>> + return 0;
>> +
>> + if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_READ)
>> + lctrl1 |= LCTRL1_CRWE_RO | LCTRL1_CRWF_RO;
>> + if ((brk->type & HW_BRK_TYPE_RDWR) == HW_BRK_TYPE_WRITE)
>> + lctrl1 |= LCTRL1_CRWE_WO | LCTRL1_CRWF_WO;
>> +
>> + mtspr(SPRN_CMPE, brk->address - 1);
>> + mtspr(SPRN_CMPF, brk->address + brk->len);
>> + mtspr(SPRN_LCTRL1, lctrl1);
>> + mtspr(SPRN_LCTRL2, lctrl2);
>> +
>> + return 0;
>> +}
>> +
>> void __set_breakpoint(struct arch_hw_breakpoint *brk)
>> {
>> memcpy(this_cpu_ptr(¤t_brk), brk, sizeof(*brk));
>> @@ -800,6 +809,8 @@ void __set_breakpoint(struct arch_hw_breakpoint *brk)
>> if (dawr_enabled())
>> // Power8 or later
>> set_dawr(brk);
>> + else if (IS_ENABLED(CONFIG_PPC_8xx))
>> + set_breakpoint_8xx(brk);
>> else if (!cpu_has_feature(CPU_FTR_ARCH_207S))
>> // Power7 or earlier
>> set_dabr(brk);
>> --
>> 2.13.3
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