Message ID | 1463670640-25701-2-git-send-email-anju@linux.vnet.ibm.com (mailing list archive) |
---|---|
State | RFC |
Headers | show |
On Thursday 19 May 2016 08:40 PM, Anju T wrote: > Detour buffer contains instructions to create an in memory pt_regs. > After the execution of prehandler a call is made for instruction emulation. > The NIP is decided after the probed instruction is executed. Hence a branch > instruction is created to the NIP returned by emulate_step(). > > Instruction slot for detour buffer is allocated from > the reserved area. For the time being 64KB is reserved > in memory for this purpose. > > Signed-off-by: Anju T <anju@linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/kprobes.h | 25 ++++++++ > arch/powerpc/kernel/optprobes_head.S | 108 +++++++++++++++++++++++++++++++++++ > 2 files changed, 133 insertions(+) > create mode 100644 arch/powerpc/kernel/optprobes_head.S > > diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h > index 039b583..3e4c998 100644 > --- a/arch/powerpc/include/asm/kprobes.h > +++ b/arch/powerpc/include/asm/kprobes.h > @@ -38,7 +38,25 @@ struct pt_regs; > struct kprobe; > > typedef ppc_opcode_t kprobe_opcode_t; > + > +extern kprobe_opcode_t optinsn_slot; > +/* Optinsn template address */ > +extern kprobe_opcode_t optprobe_template_entry[]; > +extern kprobe_opcode_t optprobe_template_call_handler[]; > +extern kprobe_opcode_t optprobe_template_call_emulate[]; > +extern kprobe_opcode_t optprobe_template_ret_branch[]; > +extern kprobe_opcode_t optprobe_template_ret[]; > +extern kprobe_opcode_t optprobe_template_insn[]; > +extern kprobe_opcode_t optprobe_template_op_address1[]; > +extern kprobe_opcode_t optprobe_template_op_address2[]; > +extern kprobe_opcode_t optprobe_template_end[]; > + > #define MAX_INSN_SIZE 1 > +#define MAX_OPTIMIZED_LENGTH 4 > +#define MAX_OPTINSN_SIZE \ > + ((unsigned long)&optprobe_template_end - \ > + (unsigned long)&optprobe_template_entry) > +#define RELATIVEJUMP_SIZE 4 > > #ifdef CONFIG_PPC64 > #if defined(_CALL_ELF) && _CALL_ELF == 2 > @@ -129,5 +147,12 @@ struct kprobe_ctlblk { > extern int kprobe_exceptions_notify(struct notifier_block *self, > unsigned long val, void *data); > extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); > + > +struct arch_optimized_insn { > + kprobe_opcode_t copied_insn[1]; > + /* detour buffer */ > + kprobe_opcode_t *insn; > +}; > + > #endif /* __KERNEL__ */ > #endif /* _ASM_POWERPC_KPROBES_H */ > diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S > new file mode 100644 > index 0000000..ce32aec > --- /dev/null > +++ b/arch/powerpc/kernel/optprobes_head.S > @@ -0,0 +1,108 @@ > +/* > + * Code to prepare detour buffer for optprobes in kernel. > + * > + * Copyright 2016, Anju T, IBM Corp. > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License > + * as published by the Free Software Foundation; either version > + * 2 of the License, or (at your option) any later version. > + */ > + > +#include <asm/ppc_asm.h> > +#include <asm/ptrace.h> > +#include <asm/asm-offsets.h> > + > +.global optinsn_slot > +optinsn_slot: > + /* Reserve an area to allocate slots for detour buffer */ > + .space 65536 Can we replace "65536" with SLOT_SIZE? > +.global optprobe_template_entry > +optprobe_template_entry: > + stdu r1,-INT_FRAME_SIZE(r1) > + SAVE_GPR(0,r1) > + /* Save the previous SP into stack */ > + addi r0,r1,INT_FRAME_SIZE > + std 0,GPR1(r1) > + SAVE_2GPRS(2,r1) > + SAVE_8GPRS(4,r1) > + SAVE_10GPRS(12,r1) > + SAVE_10GPRS(22,r1) > + /* Save SPRS */ > + mfcfar r5 > + std r5,_NIP(r1) > + mfmsr r5 > + std r5,_MSR(r1) > + mfctr r5 > + std r5,_CTR(r1) > + mflr r5 > + std r5,_LINK(r1) > + mfspr r5,SPRN_XER > + std r5,_XER(r1) > + li r5,0 > + std r5,_TRAP(r1) > + mfdar r5 > + std r5,_DAR(r1) > + mfdsisr r5 > + std r5,_DSISR(r1) We are missing _CCR (CR register)? Why tab space for the comment? and a new line before the command will be good > + /* Pass parameters for optimized_callback */ > +.global optprobe_template_op_address1 > +optprobe_template_op_address1: > + nop > + nop > + nop > + nop > + nop > + addi r4,r1,STACK_FRAME_OVERHEAD same here. > + /* Branch to the prehandler */ > +.global optprobe_template_call_handler > +optprobe_template_call_handler: > + nop > + /* Pass parameters for instruction emulation */ > + addi r3,r1,STACK_FRAME_OVERHEAD Same here and also rest of the patch > +.global optprobe_template_insn > +optprobe_template_insn: > + nop > + nop > + /* Branch to instruction emulation */ > +.global optprobe_template_call_emulate > +optprobe_template_call_emulate: > + nop > +.global optprobe_template_op_address2 > +optprobe_template_op_address2: > + nop > + nop > + nop > + nop > + nop > + addi r4,r1,STACK_FRAME_OVERHEAD > + /* Branch to create_return_branch() function */ > +.global optprobe_template_ret_branch > +optprobe_template_ret_branch: > + nop > + /* Restore the registers */ > + ld r5,_MSR(r1) > + mtmsr r5 > + ld r5,_CTR(r1) > + mtctr r5 > + ld r5,_LINK(r1) > + mtlr r5 > + ld r5,_XER(r1) > + mtxer r5 > + ld r5,_DAR(r1) > + mtdar r5 > + ld r5,_DSISR(r1) > + mtdsisr r5 Again missing CR. > + REST_GPR(0,r1) > + REST_2GPRS(2,r1) > + REST_8GPRS(4,r1) > + REST_10GPRS(12,r1) > + REST_10GPRS(22,r1) > + /* Restore the previous SP */ > + addi r1,r1,INT_FRAME_SIZE > + /* Jump back to the normal workflow from trampoline */ > +.global optprobe_template_ret > +optprobe_template_ret: > + nop > +.global optprobe_template_end > +optprobe_template_end:
On 2016/05/19 08:40PM, Anju T wrote: > Detour buffer contains instructions to create an in memory pt_regs. > After the execution of prehandler a call is made for instruction emulation. > The NIP is decided after the probed instruction is executed. Hence a branch > instruction is created to the NIP returned by emulate_step(). > > Instruction slot for detour buffer is allocated from > the reserved area. For the time being 64KB is reserved > in memory for this purpose. > > Signed-off-by: Anju T <anju@linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/kprobes.h | 25 ++++++++ > arch/powerpc/kernel/optprobes_head.S | 108 +++++++++++++++++++++++++++++++++++ > 2 files changed, 133 insertions(+) > create mode 100644 arch/powerpc/kernel/optprobes_head.S > > diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h > index 039b583..3e4c998 100644 > --- a/arch/powerpc/include/asm/kprobes.h > +++ b/arch/powerpc/include/asm/kprobes.h > @@ -38,7 +38,25 @@ struct pt_regs; > struct kprobe; > > typedef ppc_opcode_t kprobe_opcode_t; > + > +extern kprobe_opcode_t optinsn_slot; > +/* Optinsn template address */ > +extern kprobe_opcode_t optprobe_template_entry[]; > +extern kprobe_opcode_t optprobe_template_call_handler[]; > +extern kprobe_opcode_t optprobe_template_call_emulate[]; > +extern kprobe_opcode_t optprobe_template_ret_branch[]; > +extern kprobe_opcode_t optprobe_template_ret[]; > +extern kprobe_opcode_t optprobe_template_insn[]; > +extern kprobe_opcode_t optprobe_template_op_address1[]; > +extern kprobe_opcode_t optprobe_template_op_address2[]; > +extern kprobe_opcode_t optprobe_template_end[]; > + > #define MAX_INSN_SIZE 1 > +#define MAX_OPTIMIZED_LENGTH 4 > +#define MAX_OPTINSN_SIZE \ > + ((unsigned long)&optprobe_template_end - \ > + (unsigned long)&optprobe_template_entry) > +#define RELATIVEJUMP_SIZE 4 > > #ifdef CONFIG_PPC64 > #if defined(_CALL_ELF) && _CALL_ELF == 2 > @@ -129,5 +147,12 @@ struct kprobe_ctlblk { > extern int kprobe_exceptions_notify(struct notifier_block *self, > unsigned long val, void *data); > extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); > + > +struct arch_optimized_insn { > + kprobe_opcode_t copied_insn[1]; > + /* detour buffer */ > + kprobe_opcode_t *insn; > +}; > + > #endif /* __KERNEL__ */ > #endif /* _ASM_POWERPC_KPROBES_H */ > diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S > new file mode 100644 > index 0000000..ce32aec > --- /dev/null > +++ b/arch/powerpc/kernel/optprobes_head.S > @@ -0,0 +1,108 @@ > +/* > + * Code to prepare detour buffer for optprobes in kernel. > + * > + * Copyright 2016, Anju T, IBM Corp. > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License > + * as published by the Free Software Foundation; either version > + * 2 of the License, or (at your option) any later version. > + */ > + > +#include <asm/ppc_asm.h> > +#include <asm/ptrace.h> > +#include <asm/asm-offsets.h> > + > +.global optinsn_slot > +optinsn_slot: > + /* Reserve an area to allocate slots for detour buffer */ > + .space 65536 > +.global optprobe_template_entry > +optprobe_template_entry: > + stdu r1,-INT_FRAME_SIZE(r1) > + SAVE_GPR(0,r1) > + /* Save the previous SP into stack */ > + addi r0,r1,INT_FRAME_SIZE > + std 0,GPR1(r1) > + SAVE_2GPRS(2,r1) > + SAVE_8GPRS(4,r1) > + SAVE_10GPRS(12,r1) > + SAVE_10GPRS(22,r1) > + /* Save SPRS */ > + mfcfar r5 > + std r5,_NIP(r1) I think this will not work. Looking through the code, I don't see us saving/restoring CFAR across interrupts. Also, per the ISA: "The Come-From Address Register (CFAR) is a 64-bit register. When an rfebb, rfid, or rfscv instruction is executed, the register is set to the effective address of the instruction." So, it looks like we actually can't save/restore it anyway. Regardless, NIP is the same as the kprobe'd address, so you should be able to either use immediate loads or load the address from kprobe structure. - Naveen
On 2016/05/24 03:45PM, Madhavan Srinivasan wrote: > > > On Thursday 19 May 2016 08:40 PM, Anju T wrote: > > Detour buffer contains instructions to create an in memory pt_regs. > > After the execution of prehandler a call is made for instruction emulation. > > The NIP is decided after the probed instruction is executed. Hence a branch > > instruction is created to the NIP returned by emulate_step(). > > > > Instruction slot for detour buffer is allocated from > > the reserved area. For the time being 64KB is reserved > > in memory for this purpose. > > > > Signed-off-by: Anju T <anju@linux.vnet.ibm.com> > > --- > > arch/powerpc/include/asm/kprobes.h | 25 ++++++++ > > arch/powerpc/kernel/optprobes_head.S | 108 +++++++++++++++++++++++++++++++++++ > > 2 files changed, 133 insertions(+) > > create mode 100644 arch/powerpc/kernel/optprobes_head.S > > > > diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h > > index 039b583..3e4c998 100644 > > --- a/arch/powerpc/include/asm/kprobes.h > > +++ b/arch/powerpc/include/asm/kprobes.h > > @@ -38,7 +38,25 @@ struct pt_regs; > > struct kprobe; > > > > typedef ppc_opcode_t kprobe_opcode_t; > > + > > +extern kprobe_opcode_t optinsn_slot; > > +/* Optinsn template address */ > > +extern kprobe_opcode_t optprobe_template_entry[]; > > +extern kprobe_opcode_t optprobe_template_call_handler[]; > > +extern kprobe_opcode_t optprobe_template_call_emulate[]; > > +extern kprobe_opcode_t optprobe_template_ret_branch[]; > > +extern kprobe_opcode_t optprobe_template_ret[]; > > +extern kprobe_opcode_t optprobe_template_insn[]; > > +extern kprobe_opcode_t optprobe_template_op_address1[]; > > +extern kprobe_opcode_t optprobe_template_op_address2[]; > > +extern kprobe_opcode_t optprobe_template_end[]; > > + > > #define MAX_INSN_SIZE 1 > > +#define MAX_OPTIMIZED_LENGTH 4 > > +#define MAX_OPTINSN_SIZE \ > > + ((unsigned long)&optprobe_template_end - \ > > + (unsigned long)&optprobe_template_entry) > > +#define RELATIVEJUMP_SIZE 4 > > > > #ifdef CONFIG_PPC64 > > #if defined(_CALL_ELF) && _CALL_ELF == 2 > > @@ -129,5 +147,12 @@ struct kprobe_ctlblk { > > extern int kprobe_exceptions_notify(struct notifier_block *self, > > unsigned long val, void *data); > > extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); > > + > > +struct arch_optimized_insn { > > + kprobe_opcode_t copied_insn[1]; > > + /* detour buffer */ > > + kprobe_opcode_t *insn; > > +}; > > + > > #endif /* __KERNEL__ */ > > #endif /* _ASM_POWERPC_KPROBES_H */ > > diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S > > new file mode 100644 > > index 0000000..ce32aec > > --- /dev/null > > +++ b/arch/powerpc/kernel/optprobes_head.S > > @@ -0,0 +1,108 @@ > > +/* > > + * Code to prepare detour buffer for optprobes in kernel. > > + * > > + * Copyright 2016, Anju T, IBM Corp. > > + * > > + * This program is free software; you can redistribute it and/or > > + * modify it under the terms of the GNU General Public License > > + * as published by the Free Software Foundation; either version > > + * 2 of the License, or (at your option) any later version. > > + */ > > + > > +#include <asm/ppc_asm.h> > > +#include <asm/ptrace.h> > > +#include <asm/asm-offsets.h> > > + You should also add an align directive here: .align 2 > > +.global optinsn_slot > > +optinsn_slot: > > + /* Reserve an area to allocate slots for detour buffer */ > > + .space 65536 > > Can we replace "65536" with SLOT_SIZE? Yes, a macro will be good to have. > > > +.global optprobe_template_entry > > +optprobe_template_entry: > > + stdu r1,-INT_FRAME_SIZE(r1) > > + SAVE_GPR(0,r1) > > + /* Save the previous SP into stack */ > > + addi r0,r1,INT_FRAME_SIZE > > + std 0,GPR1(r1) > > + SAVE_2GPRS(2,r1) > > + SAVE_8GPRS(4,r1) > > + SAVE_10GPRS(12,r1) > > + SAVE_10GPRS(22,r1) > > + /* Save SPRS */ > > + mfcfar r5 > > + std r5,_NIP(r1) > > + mfmsr r5 > > + std r5,_MSR(r1) > > + mfctr r5 > > + std r5,_CTR(r1) > > + mflr r5 > > + std r5,_LINK(r1) > > + mfspr r5,SPRN_XER > > + std r5,_XER(r1) > > + li r5,0 > > + std r5,_TRAP(r1) > > + mfdar r5 > > + std r5,_DAR(r1) > > + mfdsisr r5 > > + std r5,_DSISR(r1) > > We are missing _CCR (CR register)? Yes, and I think we need to ensure we fill reasonable values for all registers in pt_regs including softe (from paca), orig_gpr3 (0?) and result (0). > > Why tab space for the comment? and > a new line before the command will be good ... new line before *each section* will be good :) > > > + /* Pass parameters for optimized_callback */ > > +.global optprobe_template_op_address1 > > +optprobe_template_op_address1: So, the general style is to align labels at the start of a line and to align everything else as per the code indentation. In this case though, I think it's best to use a macro for better readability. Something like: #define _GLOB(name) .global name; \ name: - Naveen
diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h index 039b583..3e4c998 100644 --- a/arch/powerpc/include/asm/kprobes.h +++ b/arch/powerpc/include/asm/kprobes.h @@ -38,7 +38,25 @@ struct pt_regs; struct kprobe; typedef ppc_opcode_t kprobe_opcode_t; + +extern kprobe_opcode_t optinsn_slot; +/* Optinsn template address */ +extern kprobe_opcode_t optprobe_template_entry[]; +extern kprobe_opcode_t optprobe_template_call_handler[]; +extern kprobe_opcode_t optprobe_template_call_emulate[]; +extern kprobe_opcode_t optprobe_template_ret_branch[]; +extern kprobe_opcode_t optprobe_template_ret[]; +extern kprobe_opcode_t optprobe_template_insn[]; +extern kprobe_opcode_t optprobe_template_op_address1[]; +extern kprobe_opcode_t optprobe_template_op_address2[]; +extern kprobe_opcode_t optprobe_template_end[]; + #define MAX_INSN_SIZE 1 +#define MAX_OPTIMIZED_LENGTH 4 +#define MAX_OPTINSN_SIZE \ + ((unsigned long)&optprobe_template_end - \ + (unsigned long)&optprobe_template_entry) +#define RELATIVEJUMP_SIZE 4 #ifdef CONFIG_PPC64 #if defined(_CALL_ELF) && _CALL_ELF == 2 @@ -129,5 +147,12 @@ struct kprobe_ctlblk { extern int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data); extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr); + +struct arch_optimized_insn { + kprobe_opcode_t copied_insn[1]; + /* detour buffer */ + kprobe_opcode_t *insn; +}; + #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_KPROBES_H */ diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S new file mode 100644 index 0000000..ce32aec --- /dev/null +++ b/arch/powerpc/kernel/optprobes_head.S @@ -0,0 +1,108 @@ +/* + * Code to prepare detour buffer for optprobes in kernel. + * + * Copyright 2016, Anju T, IBM Corp. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <asm/ppc_asm.h> +#include <asm/ptrace.h> +#include <asm/asm-offsets.h> + +.global optinsn_slot +optinsn_slot: + /* Reserve an area to allocate slots for detour buffer */ + .space 65536 +.global optprobe_template_entry +optprobe_template_entry: + stdu r1,-INT_FRAME_SIZE(r1) + SAVE_GPR(0,r1) + /* Save the previous SP into stack */ + addi r0,r1,INT_FRAME_SIZE + std 0,GPR1(r1) + SAVE_2GPRS(2,r1) + SAVE_8GPRS(4,r1) + SAVE_10GPRS(12,r1) + SAVE_10GPRS(22,r1) + /* Save SPRS */ + mfcfar r5 + std r5,_NIP(r1) + mfmsr r5 + std r5,_MSR(r1) + mfctr r5 + std r5,_CTR(r1) + mflr r5 + std r5,_LINK(r1) + mfspr r5,SPRN_XER + std r5,_XER(r1) + li r5,0 + std r5,_TRAP(r1) + mfdar r5 + std r5,_DAR(r1) + mfdsisr r5 + std r5,_DSISR(r1) + /* Pass parameters for optimized_callback */ +.global optprobe_template_op_address1 +optprobe_template_op_address1: + nop + nop + nop + nop + nop + addi r4,r1,STACK_FRAME_OVERHEAD + /* Branch to the prehandler */ +.global optprobe_template_call_handler +optprobe_template_call_handler: + nop + /* Pass parameters for instruction emulation */ + addi r3,r1,STACK_FRAME_OVERHEAD +.global optprobe_template_insn +optprobe_template_insn: + nop + nop + /* Branch to instruction emulation */ +.global optprobe_template_call_emulate +optprobe_template_call_emulate: + nop +.global optprobe_template_op_address2 +optprobe_template_op_address2: + nop + nop + nop + nop + nop + addi r4,r1,STACK_FRAME_OVERHEAD + /* Branch to create_return_branch() function */ +.global optprobe_template_ret_branch +optprobe_template_ret_branch: + nop + /* Restore the registers */ + ld r5,_MSR(r1) + mtmsr r5 + ld r5,_CTR(r1) + mtctr r5 + ld r5,_LINK(r1) + mtlr r5 + ld r5,_XER(r1) + mtxer r5 + ld r5,_DAR(r1) + mtdar r5 + ld r5,_DSISR(r1) + mtdsisr r5 + REST_GPR(0,r1) + REST_2GPRS(2,r1) + REST_8GPRS(4,r1) + REST_10GPRS(12,r1) + REST_10GPRS(22,r1) + /* Restore the previous SP */ + addi r1,r1,INT_FRAME_SIZE + /* Jump back to the normal workflow from trampoline */ +.global optprobe_template_ret +optprobe_template_ret: + nop +.global optprobe_template_end +optprobe_template_end:
Detour buffer contains instructions to create an in memory pt_regs. After the execution of prehandler a call is made for instruction emulation. The NIP is decided after the probed instruction is executed. Hence a branch instruction is created to the NIP returned by emulate_step(). Instruction slot for detour buffer is allocated from the reserved area. For the time being 64KB is reserved in memory for this purpose. Signed-off-by: Anju T <anju@linux.vnet.ibm.com> --- arch/powerpc/include/asm/kprobes.h | 25 ++++++++ arch/powerpc/kernel/optprobes_head.S | 108 +++++++++++++++++++++++++++++++++++ 2 files changed, 133 insertions(+) create mode 100644 arch/powerpc/kernel/optprobes_head.S