Commit 11ba1728 authored by Jiaxun Yang's avatar Jiaxun Yang Committed by Thomas Bogendoerfer
Browse files

ptrace: Introduce exception_ip arch hook 

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: default avatarJiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
parent d55347bf

arch/mips/include/asm/ptrace.h

+2 −0
Original line number Diff line number Diff line
@@ -154,6 +154,8 @@ 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 exception_ip(regs) exception_ip(regs)

#define profile_pc(regs) instruction_pointer(regs)



extern asmlinkage long syscall_trace_enter(struct pt_regs *regs, long syscall);

arch/mips/kernel/ptrace.c

+7 −0
Original line number Diff line number Diff line
@@ -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..

 *

include/linux/ptrace.h

+4 −0
Original line number Diff line number Diff line
@@ -393,6 +393,10 @@ static inline void user_single_step_report(struct pt_regs *regs) 
#define current_user_stack_pointer() user_stack_pointer(current_pt_regs())

#endif



#ifndef exception_ip

#define exception_ip(x) instruction_pointer(x)

#endif



extern int task_current_syscall(struct task_struct *target, struct syscall_info *info);



extern void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact);