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Date: Thu, 1 Feb 2024 17:13:54 +0000
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Subject: Re: [PATCH 1/3] ptrace: Introduce exception_ip arch hook
To: Xi Ruoyao <xry111@xry111.site>, Oleg Nesterov <oleg@redhat.com>,
 Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
 Andrew Morton <akpm@linux-foundation.org>,
 Ben Hutchings <ben@decadent.org.uk>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-mips@vger.kernel.org, linux-mm@kvack.org
References: <20240201-exception_ip-v1-0-aa26ab3ee0b5@flygoat.com>
 <20240201-exception_ip-v1-1-aa26ab3ee0b5@flygoat.com>
 <9d1d51e69c3f96bf5992e9a988969515ba97f883.camel@xry111.site>
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From: Jiaxun Yang <jiaxun.yang@flygoat.com>
Autocrypt: addr=jiaxun.yang@flygoat.com;
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In-Reply-To: <9d1d51e69c3f96bf5992e9a988969515ba97f883.camel@xry111.site>
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在 2024/2/1 16:35, Xi Ruoyao 写道:
> On Thu, 2024-02-01 at 15:46 +0000, Jiaxun Yang wrote:
>> On architectures with delay slot, architecture level instruction
>> pointer (or program counter) in pt_regs may differ from where
>> exception was triggered.
>>
>> Introduce exception_ip hook to invoke architecture code and determine
>> actual instruction pointer to the exception.
>>
>> Link:
>> https://lore.kernel.org/lkml/00d1b813-c55f-4365-8d81-d70258e10b16@app.fastmail.com/
>> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> How about adding something like
>
> #ifndef arch_exception_ip
> #define exception_ip(regs) instruction_pointer(regs)
> #else
> #define exception_ip(regs) arch_exception_ip(regs)
> #endif
>
> into a generic header, instead of having to add exception_ip definition
> everywhere?

Actually I tried but failed, cuz there is no asm-generic version of 
ptrace.h, besides
exception_ip shall be used at many scenarios so extable.h is also a no go.

Thanks
- Jiaxun

>
>> ---
>>   arch/alpha/include/asm/ptrace.h        | 1 +
>>   arch/arc/include/asm/ptrace.h          | 1 +
>>   arch/arm/include/asm/ptrace.h          | 1 +
>>   arch/csky/include/asm/ptrace.h         | 1 +
>>   arch/hexagon/include/uapi/asm/ptrace.h | 1 +
>>   arch/loongarch/include/asm/ptrace.h    | 1 +
>>   arch/m68k/include/asm/ptrace.h         | 1 +
>>   arch/microblaze/include/asm/ptrace.h   | 3 ++-
>>   arch/mips/include/asm/ptrace.h         | 1 +
>>   arch/mips/kernel/ptrace.c              | 7 +++++++
>>   arch/nios2/include/asm/ptrace.h        | 3 ++-
>>   arch/openrisc/include/asm/ptrace.h     | 1 +
>>   arch/parisc/include/asm/ptrace.h       | 1 +
>>   arch/s390/include/asm/ptrace.h         | 1 +
>>   arch/sparc/include/asm/ptrace.h        | 2 ++
>>   arch/um/include/asm/ptrace-generic.h   | 1 +
>>   16 files changed, 25 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/alpha/include/asm/ptrace.h
>> b/arch/alpha/include/asm/ptrace.h
>> index 3557ce64ed21..1ded3f2d09e9 100644
>> --- a/arch/alpha/include/asm/ptrace.h
>> +++ b/arch/alpha/include/asm/ptrace.h
>> @@ -8,6 +8,7 @@
>>   #define arch_has_single_step()		(1)
>>   #define user_mode(regs) (((regs)->ps & 8) != 0)
>>   #define instruction_pointer(regs) ((regs)->pc)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define profile_pc(regs) instruction_pointer(regs)
>>   #define current_user_stack_pointer() rdusp()
>>   
>> diff --git a/arch/arc/include/asm/ptrace.h
>> b/arch/arc/include/asm/ptrace.h
>> index 00b9318e551e..94084f1048df 100644
>> --- a/arch/arc/include/asm/ptrace.h
>> +++ b/arch/arc/include/asm/ptrace.h
>> @@ -105,6 +105,7 @@ struct callee_regs {
>>   #endif
>>   
>>   #define instruction_pointer(regs)	((regs)->ret)
>> +#define exception_ip(regs)		instruction_pointer(regs)
>>   #define profile_pc(regs)		instruction_pointer(regs)
>>   
>>   /* return 1 if user mode or 0 if kernel mode */
>> diff --git a/arch/arm/include/asm/ptrace.h
>> b/arch/arm/include/asm/ptrace.h
>> index 7f44e88d1f25..fb4dc23eba78 100644
>> --- a/arch/arm/include/asm/ptrace.h
>> +++ b/arch/arm/include/asm/ptrace.h
>> @@ -89,6 +89,7 @@ static inline long regs_return_value(struct pt_regs
>> *regs)
>>   }
>>   
>>   #define instruction_pointer(regs)	(regs)->ARM_pc
>> +#define
>> exception_ip(regs)			instruction_pointer(regs)
>>   
>>   #ifdef CONFIG_THUMB2_KERNEL
>>   #define frame_pointer(regs) (regs)->ARM_r7
>> diff --git a/arch/csky/include/asm/ptrace.h
>> b/arch/csky/include/asm/ptrace.h
>> index 0634b7895d81..a738630e64b0 100644
>> --- a/arch/csky/include/asm/ptrace.h
>> +++ b/arch/csky/include/asm/ptrace.h
>> @@ -22,6 +22,7 @@
>>   
>>   #define user_mode(regs) (!((regs)->sr & PS_S))
>>   #define instruction_pointer(regs) ((regs)->pc)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define profile_pc(regs) instruction_pointer(regs)
>>   #define trap_no(regs) ((regs->sr >> 16) & 0xff)
>>   
>> diff --git a/arch/hexagon/include/uapi/asm/ptrace.h
>> b/arch/hexagon/include/uapi/asm/ptrace.h
>> index 2a3ea14ad9b9..846471936237 100644
>> --- a/arch/hexagon/include/uapi/asm/ptrace.h
>> +++ b/arch/hexagon/include/uapi/asm/ptrace.h
>> @@ -25,6 +25,7 @@
>>   #include <asm/registers.h>
>>   
>>   #define instruction_pointer(regs) pt_elr(regs)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define user_stack_pointer(regs) ((regs)->r29)
>>   
>>   #define profile_pc(regs) instruction_pointer(regs)
>> diff --git a/arch/loongarch/include/asm/ptrace.h
>> b/arch/loongarch/include/asm/ptrace.h
>> index f3ddaed9ef7f..a34327f0e69d 100644
>> --- a/arch/loongarch/include/asm/ptrace.h
>> +++ b/arch/loongarch/include/asm/ptrace.h
>> @@ -160,6 +160,7 @@ static inline void regs_set_return_value(struct
>> pt_regs *regs, unsigned long val
>>   }
>>   
>>   #define instruction_pointer(regs) ((regs)->csr_era)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define profile_pc(regs) instruction_pointer(regs)
>>   
>>   extern void die(const char *str, struct pt_regs *regs);
>> diff --git a/arch/m68k/include/asm/ptrace.h
>> b/arch/m68k/include/asm/ptrace.h
>> index ea5a80ca1ab3..cb553e2ec73a 100644
>> --- a/arch/m68k/include/asm/ptrace.h
>> +++ b/arch/m68k/include/asm/ptrace.h
>> @@ -13,6 +13,7 @@
>>   
>>   #define user_mode(regs) (!((regs)->sr & PS_S))
>>   #define instruction_pointer(regs) ((regs)->pc)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define profile_pc(regs) instruction_pointer(regs)
>>   #define current_pt_regs() \
>>   	(struct pt_regs *)((char *)current_thread_info() +
>> THREAD_SIZE) - 1
>> diff --git a/arch/microblaze/include/asm/ptrace.h
>> b/arch/microblaze/include/asm/ptrace.h
>> index bfcb89df5e26..974c00fa7212 100644
>> --- a/arch/microblaze/include/asm/ptrace.h
>> +++ b/arch/microblaze/include/asm/ptrace.h
>> @@ -12,7 +12,8 @@
>>   #define user_mode(regs)			(!kernel_mode(regs))
>>   
>>   #define instruction_pointer(regs)	((regs)->pc)
>> -#define profile_pc(regs)		instruction_pointer(regs)
>> +#define
>> exception_ip(regs)			instruction_pointer(regs)
>> +#define
>> profile_pc(regs)			instruction_pointer(regs)
>>   #define user_stack_pointer(regs)	((regs)->r1)
>>   
>>   static inline long regs_return_value(struct pt_regs *regs)
>> diff --git a/arch/mips/include/asm/ptrace.h
>> b/arch/mips/include/asm/ptrace.h
>> index daf3cf244ea9..97589731fd40 100644
>> --- a/arch/mips/include/asm/ptrace.h
>> +++ b/arch/mips/include/asm/ptrace.h
>> @@ -154,6 +154,7 @@ static inline long regs_return_value(struct
>> pt_regs *regs)
>>   }
>>   
>>   #define instruction_pointer(regs) ((regs)->cp0_epc)
>> +extern unsigned long exception_ip(struct pt_regs *regs);
>>   #define profile_pc(regs) instruction_pointer(regs)
>>   
>>   extern asmlinkage long syscall_trace_enter(struct pt_regs *regs, long
>> syscall);
>> diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
>> index d9df543f7e2c..59288c13b581 100644
>> --- a/arch/mips/kernel/ptrace.c
>> +++ b/arch/mips/kernel/ptrace.c
>> @@ -31,6 +31,7 @@
>>   #include <linux/seccomp.h>
>>   #include <linux/ftrace.h>
>>   
>> +#include <asm/branch.h>
>>   #include <asm/byteorder.h>
>>   #include <asm/cpu.h>
>>   #include <asm/cpu-info.h>
>> @@ -48,6 +49,12 @@
>>   #define CREATE_TRACE_POINTS
>>   #include <trace/events/syscalls.h>
>>   
>> +unsigned long exception_ip(struct pt_regs *regs)
>> +{
>> +	return exception_epc(regs);
>> +}
>> +EXPORT_SYMBOL(exception_ip);
>> +
>>   /*
>>    * Called by kernel/ptrace.c when detaching..
>>    *
>> diff --git a/arch/nios2/include/asm/ptrace.h
>> b/arch/nios2/include/asm/ptrace.h
>> index 9da34c3022a2..136f5679ae79 100644
>> --- a/arch/nios2/include/asm/ptrace.h
>> +++ b/arch/nios2/include/asm/ptrace.h
>> @@ -66,7 +66,8 @@ struct switch_stack {
>>   #define user_mode(regs)	(((regs)->estatus & ESTATUS_EU))
>>   
>>   #define instruction_pointer(regs)	((regs)->ra)
>> -#define profile_pc(regs)		instruction_pointer(regs)
>> +#define
>> exception_ip(regs)			instruction_pointer(regs)
>> +#define
>> profile_pc(regs)			instruction_pointer(regs)
>>   #define user_stack_pointer(regs)	((regs)->sp)
>>   extern void show_regs(struct pt_regs *);
>>   
>> diff --git a/arch/openrisc/include/asm/ptrace.h
>> b/arch/openrisc/include/asm/ptrace.h
>> index 375147ff71fc..67c28484d17e 100644
>> --- a/arch/openrisc/include/asm/ptrace.h
>> +++ b/arch/openrisc/include/asm/ptrace.h
>> @@ -67,6 +67,7 @@ struct pt_regs {
>>   #define STACK_FRAME_OVERHEAD  128  /* size of minimum stack frame */
>>   
>>   #define instruction_pointer(regs)	((regs)->pc)
>> +#define
>> exception_ip(regs)			instruction_pointer(regs)
>>   #define user_mode(regs)			(((regs)->sr &
>> SPR_SR_SM) == 0)
>>   #define user_stack_pointer(regs)	((unsigned long)(regs)->sp)
>>   #define profile_pc(regs)		instruction_pointer(regs)
>> diff --git a/arch/parisc/include/asm/ptrace.h
>> b/arch/parisc/include/asm/ptrace.h
>> index eea3f3df0823..d7e8dcf26582 100644
>> --- a/arch/parisc/include/asm/ptrace.h
>> +++ b/arch/parisc/include/asm/ptrace.h
>> @@ -17,6 +17,7 @@
>>   #define user_mode(regs)			(((regs)->iaoq[0] &
>> 3) != PRIV_KERNEL)
>>   #define user_space(regs)		((regs)->iasq[1] !=
>> PRIV_KERNEL)
>>   #define instruction_pointer(regs)	((regs)->iaoq[0] & ~3)
>> +#define
>> exception_ip(regs)			instruction_pointer(regs)
>>   #define user_stack_pointer(regs)	((regs)->gr[30])
>>   unsigned long profile_pc(struct pt_regs *);
>>   
>> diff --git a/arch/s390/include/asm/ptrace.h
>> b/arch/s390/include/asm/ptrace.h
>> index d28bf8fb2799..a5255b2337af 100644
>> --- a/arch/s390/include/asm/ptrace.h
>> +++ b/arch/s390/include/asm/ptrace.h
>> @@ -211,6 +211,7 @@ static inline int
>> test_and_clear_pt_regs_flag(struct pt_regs *regs, int flag)
>>   
>>   #define user_mode(regs) (((regs)->psw.mask & PSW_MASK_PSTATE) != 0)
>>   #define instruction_pointer(regs) ((regs)->psw.addr)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define user_stack_pointer(regs)((regs)->gprs[15])
>>   #define profile_pc(regs) instruction_pointer(regs)
>>   
>> diff --git a/arch/sparc/include/asm/ptrace.h
>> b/arch/sparc/include/asm/ptrace.h
>> index d1419e669027..41ae186f2245 100644
>> --- a/arch/sparc/include/asm/ptrace.h
>> +++ b/arch/sparc/include/asm/ptrace.h
>> @@ -63,6 +63,7 @@ extern union global_cpu_snapshot
>> global_cpu_snapshot[NR_CPUS];
>>   #define force_successful_syscall_return() set_thread_noerror(1)
>>   #define user_mode(regs) (!((regs)->tstate & TSTATE_PRIV))
>>   #define instruction_pointer(regs) ((regs)->tpc)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define instruction_pointer_set(regs, val) do { \
>>   		(regs)->tpc = (val); \
>>   		(regs)->tnpc = (val)+4; \
>> @@ -142,6 +143,7 @@ static inline bool pt_regs_clear_syscall(struct
>> pt_regs *regs)
>>   
>>   #define user_mode(regs) (!((regs)->psr & PSR_PS))
>>   #define instruction_pointer(regs) ((regs)->pc)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   #define user_stack_pointer(regs) ((regs)->u_regs[UREG_FP])
>>   unsigned long profile_pc(struct pt_regs *);
>>   #else /* (!__ASSEMBLY__) */
>> diff --git a/arch/um/include/asm/ptrace-generic.h
>> b/arch/um/include/asm/ptrace-generic.h
>> index adf91ef553ae..f9ada287ca12 100644
>> --- a/arch/um/include/asm/ptrace-generic.h
>> +++ b/arch/um/include/asm/ptrace-generic.h
>> @@ -26,6 +26,7 @@ struct pt_regs {
>>   #define PT_REGS_SYSCALL_NR(r) UPT_SYSCALL_NR(&(r)->regs)
>>   
>>   #define instruction_pointer(regs) PT_REGS_IP(regs)
>> +#define exception_ip(regs) instruction_pointer(regs)
>>   
>>   #define PTRACE_OLDSETOPTIONS 21
>>   
>>

-- 
---
Jiaxun Yang