[PATCH V2 3/4] arch/powerpc: Implement Optprobes
Anju T Sudhakar
anju at linux.vnet.ibm.com
Sat Dec 17 04:54:54 AEDT 2016
Hi Masami,
On Friday 16 December 2016 07:32 PM, Masami Hiramatsu wrote:
> On Wed, 14 Dec 2016 21:48:27 +0530
> Anju T Sudhakar <anju at linux.vnet.ibm.com> wrote:
>
>> Detour buffer contains instructions to create an in memory pt_regs.
>> After the execution of the pre-handler, a call is made for instruction emulation.
>> The NIP is determined in advanced through dummy instruction emulation and a branch
>> instruction is created to the NIP at the end of the trampoline.
>>
>> Instruction slot for detour buffer is allocated from the reserved area.
>> For the time being, 64KB is reserved in memory for this purpose.
>>
>> Instructions which can be emulated using analyse_instr() are suppliants
>> for optimization. Before optimization ensure that the address range
>> between the detour buffer allocated and the instruction being probed
>> is within ± 32MB.
> Thank you for updating!
> I think this has no critical issue, but I have some comments on it.
> (just cleanup and hardenings)
> Please see below.
>
>> Signed-off-by: Anju T Sudhakar <anju at linux.vnet.ibm.com>
>> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
>> ---
>> .../features/debug/optprobes/arch-support.txt | 2 +-
>> arch/powerpc/Kconfig | 1 +
>> arch/powerpc/include/asm/kprobes.h | 23 +-
>> arch/powerpc/include/asm/sstep.h | 1 +
>> arch/powerpc/kernel/Makefile | 1 +
>> arch/powerpc/kernel/optprobes.c | 333 +++++++++++++++++++++
>> arch/powerpc/kernel/optprobes_head.S | 135 +++++++++
>> arch/powerpc/lib/sstep.c | 22 ++
>> 8 files changed, 516 insertions(+), 2 deletions(-)
>> create mode 100644 arch/powerpc/kernel/optprobes.c
>> create mode 100644 arch/powerpc/kernel/optprobes_head.S
>>
>> diff --git a/Documentation/features/debug/optprobes/arch-support.txt b/Documentation/features/debug/optprobes/arch-support.txt
>> index b8999d8..45bc99d 100644
>> --- a/Documentation/features/debug/optprobes/arch-support.txt
>> +++ b/Documentation/features/debug/optprobes/arch-support.txt
>> @@ -27,7 +27,7 @@
>> | nios2: | TODO |
>> | openrisc: | TODO |
>> | parisc: | TODO |
>> - | powerpc: | TODO |
>> + | powerpc: | ok |
>> | s390: | TODO |
>> | score: | TODO |
>> | sh: | TODO |
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index c7f120a..d563f0a 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -98,6 +98,7 @@ config PPC
>> select HAVE_IOREMAP_PROT
>> select HAVE_EFFICIENT_UNALIGNED_ACCESS if !(CPU_LITTLE_ENDIAN && POWER7_CPU)
>> select HAVE_KPROBES
>> + select HAVE_OPTPROBES if PPC64
>> select HAVE_ARCH_KGDB
>> select HAVE_KRETPROBES
>> select HAVE_ARCH_TRACEHOOK
>> diff --git a/arch/powerpc/include/asm/kprobes.h b/arch/powerpc/include/asm/kprobes.h
>> index 2c9759bd..739ddc5 100644
>> --- a/arch/powerpc/include/asm/kprobes.h
>> +++ b/arch/powerpc/include/asm/kprobes.h
>> @@ -38,7 +38,22 @@ struct pt_regs;
>> struct kprobe;
>>
>> typedef ppc_opcode_t kprobe_opcode_t;
>> -#define MAX_INSN_SIZE 1
>> +
>> +extern kprobe_opcode_t optinsn_slot;
>> +
>> +/* Optinsn template address */
>> +extern kprobe_opcode_t optprobe_template_entry[];
>> +extern kprobe_opcode_t optprobe_template_op_address[];
>> +extern kprobe_opcode_t optprobe_template_call_handler[];
>> +extern kprobe_opcode_t optprobe_template_insn[];
>> +extern kprobe_opcode_t optprobe_template_call_emulate[];
>> +extern kprobe_opcode_t optprobe_template_ret[];
>> +extern kprobe_opcode_t optprobe_template_end[];
>> +
>> +#define MAX_INSN_SIZE 1
>> +#define MAX_OPTIMIZED_LENGTH 4
>> +#define MAX_OPTINSN_SIZE (optprobe_template_end - optprobe_template_entry)
>> +#define RELATIVEJUMP_SIZE 4
> These size/length macros seems a bit odd. I guess MAX_INSN_SIZE
> is based on sizeof(MAX_INSN_SIZE), but others are in byte.
> Could you fix that? For example, define it with
> sizeof(kprobe_opcode_t), and add comments on it, etc.
Sure. I will look into this and define it in a consistent way.
>>
>> #ifdef PPC64_ELF_ABI_v2
>> /* PPC64 ABIv2 needs local entry point */
>> @@ -124,6 +139,12 @@ struct kprobe_ctlblk {
>> struct prev_kprobe prev_kprobe;
>> };
>>
>> +struct arch_optimized_insn {
>> + kprobe_opcode_t copied_insn[1];
>> + /* detour buffer */
>> + kprobe_opcode_t *insn;
>> +};
>> +
>> 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);
>> diff --git a/arch/powerpc/include/asm/sstep.h b/arch/powerpc/include/asm/sstep.h
>> index d3a42cc..f7ad425 100644
>> --- a/arch/powerpc/include/asm/sstep.h
>> +++ b/arch/powerpc/include/asm/sstep.h
>> @@ -87,3 +87,4 @@ struct instruction_op {
>>
>> extern int analyse_instr(struct instruction_op *op, struct pt_regs *regs,
>> unsigned int instr);
>> +extern bool is_conditional_branch(unsigned int instr);
>> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
>> index 1925341..54f0f47 100644
>> --- a/arch/powerpc/kernel/Makefile
>> +++ b/arch/powerpc/kernel/Makefile
>> @@ -98,6 +98,7 @@ obj-$(CONFIG_KGDB) += kgdb.o
>> obj-$(CONFIG_BOOTX_TEXT) += btext.o
>> obj-$(CONFIG_SMP) += smp.o
>> obj-$(CONFIG_KPROBES) += kprobes.o
>> +obj-$(CONFIG_OPTPROBES) += optprobes.o optprobes_head.o
>> obj-$(CONFIG_UPROBES) += uprobes.o
>> obj-$(CONFIG_PPC_UDBG_16550) += legacy_serial.o udbg_16550.o
>> obj-$(CONFIG_STACKTRACE) += stacktrace.o
>> diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
>> new file mode 100644
>> index 0000000..ecba221
>> --- /dev/null
>> +++ b/arch/powerpc/kernel/optprobes.c
>> @@ -0,0 +1,333 @@
>> +/*
>> + * Code for Kernel probes Jump optimization.
>> + *
>> + * 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 <linux/kprobes.h>
>> +#include <linux/jump_label.h>
>> +#include <linux/types.h>
>> +#include <linux/slab.h>
>> +#include <linux/list.h>
>> +#include <asm/kprobes.h>
>> +#include <asm/ptrace.h>
>> +#include <asm/cacheflush.h>
>> +#include <asm/code-patching.h>
>> +#include <asm/sstep.h>
>> +#include <asm/ppc-opcode.h>
>> +
>> +#define TMPL_CALL_HDLR_IDX \
>> + (optprobe_template_call_handler - optprobe_template_entry)
>> +#define TMPL_EMULATE_IDX \
>> + (optprobe_template_call_emulate - optprobe_template_entry)
>> +#define TMPL_RET_IDX \
>> + (optprobe_template_ret - optprobe_template_entry)
>> +#define TMPL_OP_IDX \
>> + (optprobe_template_op_address - optprobe_template_entry)
>> +#define TMPL_INSN_IDX \
>> + (optprobe_template_insn - optprobe_template_entry)
>> +#define TMPL_END_IDX \
>> + (optprobe_template_end - optprobe_template_entry)
>> +
>> +DEFINE_INSN_CACHE_OPS(ppc_optinsn);
>> +
>> +static bool insn_page_in_use;
>> +
>> +static void *__ppc_alloc_insn_page(void)
>> +{
>> + if (insn_page_in_use)
>> + return NULL;
>> + insn_page_in_use = true;
>> + return &optinsn_slot;
>> +}
>> +
>> +static void __ppc_free_insn_page(void *page __maybe_unused)
>> +{
>> + insn_page_in_use = false;
>> +}
>> +
>> +struct kprobe_insn_cache kprobe_ppc_optinsn_slots = {
>> + .mutex = __MUTEX_INITIALIZER(kprobe_ppc_optinsn_slots.mutex),
>> + .pages = LIST_HEAD_INIT(kprobe_ppc_optinsn_slots.pages),
>> + /* insn_size initialized later */
>> + .alloc = __ppc_alloc_insn_page,
>> + .free = __ppc_free_insn_page,
>> + .nr_garbage = 0,
>> +};
>> +
>> +/*
>> + * Check if we can optimize this probe. Returns NIP post-emulation if this can
>> + * be optimized and 0 otherwise.
>> + */
>> +static unsigned long can_optimize(struct kprobe *p)
>> +{
>> + struct pt_regs regs;
>> + struct instruction_op op;
>> + unsigned long nip = 0;
>> +
>> + /*
>> + * kprobe placed for kretprobe during boot time
>> + * is not optimizing now.
>> + *
>> + * TODO: Optimize kprobe in kretprobe_trampoline
>> + */
>> + if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
>> + return 0;
>> +
>> + /*
>> + * We only support optimizing kernel addresses, but not
>> + * module addresses.
>> + */
>> + if (!is_kernel_addr((unsigned long)p->addr))
>> + return 0;
>> +
>> + regs.nip = (unsigned long)p->addr;
>> + regs.trap = 0x0;
>> + regs.msr = MSR_KERNEL;
>> +
>> + /*
>> + * Ensure that the instruction is not a conditional branch,
>> + * and that can be emulated.
>> + */
>> + if (!is_conditional_branch(*p->ainsn.insn) &&
>> + analyse_instr(&op, ®s, *p->ainsn.insn))
>> + nip = regs.nip;
>> +
>> + return nip;
>> +}
>> +
>> +static void optimized_callback(struct optimized_kprobe *op,
>> + struct pt_regs *regs)
>> +{
>> + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
>> + unsigned long flags;
>> +
>> + /* This is possible if op is under delayed unoptimizing */
>> + if (kprobe_disabled(&op->kp))
>> + return;
>> +
>> + local_irq_save(flags);
>> +
>> + if (kprobe_running()) {
>> + kprobes_inc_nmissed_count(&op->kp);
>> + } else {
>> + __this_cpu_write(current_kprobe, &op->kp);
>> + regs->nip = (unsigned long)op->kp.addr;
>> + kcb->kprobe_status = KPROBE_HIT_ACTIVE;
>> + opt_pre_handler(&op->kp, regs);
>> + __this_cpu_write(current_kprobe, NULL);
>> + }
>> + local_irq_restore(flags);
>> +}
>> +NOKPROBE_SYMBOL(optimized_callback);
>> +
>> +void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
>> +{
>> + if (op->optinsn.insn) {
>> + free_ppc_optinsn_slot(op->optinsn.insn, 1);
>> + op->optinsn.insn = NULL;
>> + }
>> +}
>> +
>> +/*
>> + * emulate_step() requires insn to be emulated as
>> + * second parameter. Load register 'r4' with the
>> + * instruction.
>> + */
>> +void patch_imm32_load_insns(unsigned int val, kprobe_opcode_t *addr)
>> +{
>> + /* addis r4,0,(insn)@h */
>> + *addr++ = PPC_INST_ADDIS | ___PPC_RT(4) |
>> + ((val >> 16) & 0xffff);
>> +
>> + /* ori r4,r4,(insn)@l */
>> + *addr = PPC_INST_ORI | ___PPC_RA(4) | ___PPC_RS(4) |
>> + (val & 0xffff);
>> +}
>> +
>> +/*
>> + * Generate instructions to load provided immediate 64-bit value
>> + * to register 'r3' and patch these instructions at 'addr'.
>> + */
>> +void patch_imm64_load_insns(unsigned long val, kprobe_opcode_t *addr)
>> +{
>> + /* lis r3,(op)@highest */
>> + *addr++ = PPC_INST_ADDIS | ___PPC_RT(3) |
>> + ((val >> 48) & 0xffff);
>> +
>> + /* ori r3,r3,(op)@higher */
>> + *addr++ = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
>> + ((val >> 32) & 0xffff);
>> +
>> + /* rldicr r3,r3,32,31 */
>> + *addr++ = PPC_INST_RLDICR | ___PPC_RA(3) | ___PPC_RS(3) |
>> + __PPC_SH64(32) | __PPC_ME64(31);
>> +
>> + /* oris r3,r3,(op)@h */
>> + *addr++ = PPC_INST_ORIS | ___PPC_RA(3) | ___PPC_RS(3) |
>> + ((val >> 16) & 0xffff);
>> +
>> + /* ori r3,r3,(op)@l */
>> + *addr = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
>> + (val & 0xffff);
>> +}
> I need another PPC maintainer review for these.
ok.
>> +
>> +int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
>> +{
>> + kprobe_opcode_t *buff, branch_op_callback, branch_emulate_step;
>> + kprobe_opcode_t *op_callback_addr, *emulate_step_addr;
>> + long b_offset;
>> + unsigned long nip;
>> +
>> + kprobe_ppc_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
>> +
>> + nip = can_optimize(p);
>> + if (!nip)
>> + return -EILSEQ;
>> +
>> + /* Allocate instruction slot for detour buffer */
>> + buff = get_ppc_optinsn_slot();
>> + if (!buff)
>> + return -ENOMEM;
>> +
>> + /*
>> + * OPTPROBE uses 'b' instruction to branch to optinsn.insn.
>> + *
>> + * The target address has to be relatively nearby, to permit use
>> + * of branch instruction in powerpc, because the address is specified
>> + * in an immediate field in the instruction opcode itself, ie 24 bits
>> + * in the opcode specify the address. Therefore the address should
>> + * be within 32MB on either side of the current instruction.
>> + */
>> + b_offset = (unsigned long)buff - (unsigned long)p->addr;
>> + if (!is_offset_in_branch_range(b_offset)) {
>> + free_ppc_optinsn_slot(buff, 0);
>> + return -ERANGE;
>> + }
>> +
>> + /* Check if the return address is also within 32MB range */
>> + b_offset = (unsigned long)(buff + TMPL_RET_IDX) -
>> + (unsigned long)nip;
>> + if (!is_offset_in_branch_range(b_offset)) {
>> + free_ppc_optinsn_slot(buff, 0);
>> + return -ERANGE;
>> + }
>> +
>> + /* Setup template */
>> + memcpy(buff, optprobe_template_entry,
>> + TMPL_END_IDX * sizeof(kprobe_opcode_t));
>> +
>> + /*
>> + * Fixup the template with instructions to:
>> + * 1. load the address of the actual probepoint
>> + */
>> + patch_imm64_load_insns((unsigned long)op, buff + TMPL_OP_IDX);
>> +
>> + /*
>> + * 2. branch to optimized_callback() and emulate_step()
>> + */
>> + kprobe_lookup_name("optimized_callback", op_callback_addr);
>> + kprobe_lookup_name("emulate_step", emulate_step_addr);
>> + if (!op_callback_addr || !emulate_step_addr) {
>> + free_ppc_optinsn_slot(buff, 0);
>> + WARN(1, "kprobe_lookup_name() failed\n");
>> + return -ENOENT;
>> + }
>> +
>> + branch_op_callback = create_branch((unsigned int *)buff + TMPL_CALL_HDLR_IDX,
>> + (unsigned long)op_callback_addr,
>> + BRANCH_SET_LINK);
>> +
>> + branch_emulate_step = create_branch((unsigned int *)buff + TMPL_EMULATE_IDX,
>> + (unsigned long)emulate_step_addr,
>> + BRANCH_SET_LINK);
>> +
>> + if (!branch_op_callback || !branch_emulate_step) {
>> + free_ppc_optinsn_slot(buff, 0);
>> + return -ERANGE;
> Since there are 4 free_ppc_optinsn_slot(buff, 0) and return error pattarns,
> I recommend you to consolidate it by using "goto error".
Ah, nice suggestion. Will change this. Thanks!
>> + }
>> +
>> + buff[TMPL_CALL_HDLR_IDX] = branch_op_callback;
>> + buff[TMPL_EMULATE_IDX] = branch_emulate_step;
>> +
>> + /*
>> + * 3. load instruction to be emulated into relevant register, and
>> + */
>> + patch_imm32_load_insns(*p->ainsn.insn, buff + TMPL_INSN_IDX);
>> +
>> + /*
>> + * 4. branch back from trampoline
>> + */
>> + buff[TMPL_RET_IDX] = create_branch((unsigned int *)buff + TMPL_RET_IDX,
>> + (unsigned long)nip, 0);
>> +
>> + flush_icache_range((unsigned long)buff,
>> + (unsigned long)(&buff[TMPL_END_IDX]));
>> +
>> + op->optinsn.insn = buff;
>> +
>> + return 0;
>> +}
>> +
>> +int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)
>> +{
>> + return optinsn->insn != NULL;
>> +}
>> +
>> +/*
>> + * On powerpc, Optprobes always replaces one instruction (4 bytes
>> + * aligned and 4 bytes long). It is impossible to encounter another
>> + * kprobe in this address range. So always return 0.
>> + */
>> +int arch_check_optimized_kprobe(struct optimized_kprobe *op)
>> +{
>> + return 0;
>> +}
>> +
>> +void arch_optimize_kprobes(struct list_head *oplist)
>> +{
>> + struct optimized_kprobe *op;
>> + struct optimized_kprobe *tmp;
>> +
>> + list_for_each_entry_safe(op, tmp, oplist, list) {
>> + /*
>> + * Backup instructions which will be replaced
>> + * by jump address
>> + */
>> + memcpy(op->optinsn.copied_insn, op->kp.addr,
>> + RELATIVEJUMP_SIZE);
>> + patch_instruction(op->kp.addr,
>> + create_branch((unsigned int *)op->kp.addr,
>> + (unsigned long)op->optinsn.insn, 0));
> Would you be sure that create_branch doesn't fail?
The b_offset check we did, before optimizing the kprobe will guarantee
that the branch will be in +/- 32MB range. So create_branch will not fail.
>
>> + list_del_init(&op->list);
>> + }
>> +}
>> +
>> +void arch_unoptimize_kprobe(struct optimized_kprobe *op)
>> +{
>> + arch_arm_kprobe(&op->kp);
>> +}
>> +
>> +void arch_unoptimize_kprobes(struct list_head *oplist,
>> + struct list_head *done_list)
>> +{
>> + struct optimized_kprobe *op;
>> + struct optimized_kprobe *tmp;
>> +
>> + list_for_each_entry_safe(op, tmp, oplist, list) {
>> + arch_unoptimize_kprobe(op);
>> + list_move(&op->list, done_list);
>> + }
>> +}
>> +
>> +int arch_within_optimized_kprobe(struct optimized_kprobe *op,
>> + unsigned long addr)
>> +{
>> + return ((unsigned long)op->kp.addr <= addr &&
>> + (unsigned long)op->kp.addr + RELATIVEJUMP_SIZE > addr);
>> +}
>> diff --git a/arch/powerpc/kernel/optprobes_head.S b/arch/powerpc/kernel/optprobes_head.S
>> new file mode 100644
>> index 0000000..c86976b
>> --- /dev/null
>> +++ b/arch/powerpc/kernel/optprobes_head.S
>> @@ -0,0 +1,135 @@
>> +/*
>> + * 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>
>> +
>> +#define OPT_SLOT_SIZE 65536
>> +
>> + .balign 4
>> +
>> + /*
>> + * Reserve an area to allocate slots for detour buffer.
>> + * This is part of .text section (rather than vmalloc area)
>> + * as this needs to be within 32MB of the probed address.
>> + */
>> + .global optinsn_slot
>> +optinsn_slot:
>> + .space OPT_SLOT_SIZE
>> +
>> + /*
>> + * Optprobe template:
>> + * This template gets copied into one of the slots in optinsn_slot
>> + * and gets fixed up with real optprobe structures et al.
>> + */
>> + .global optprobe_template_entry
>> +optprobe_template_entry:
>> + /* Create an in-memory pt_regs */
>> + stdu r1,-INT_FRAME_SIZE(r1)
>> + SAVE_GPR(0,r1)
>> + /* Save the previous SP into stack */
>> + addi r0,r1,INT_FRAME_SIZE
>> + std r0,GPR1(r1)
>> + SAVE_10GPRS(2,r1)
>> + SAVE_10GPRS(12,r1)
>> + SAVE_10GPRS(22,r1)
>> + /* Save SPRS */
>> + mfmsr r5
>> + std r5,_MSR(r1)
>> + li r5,0x700
>> + std r5,_TRAP(r1)
>> + li r5,0
>> + std r5,ORIG_GPR3(r1)
>> + std r5,RESULT(r1)
>> + mfctr r5
>> + std r5,_CTR(r1)
>> + mflr r5
>> + std r5,_LINK(r1)
>> + mfspr r5,SPRN_XER
>> + std r5,_XER(r1)
>> + mfcr r5
>> + std r5,_CCR(r1)
>> + lbz r5,PACASOFTIRQEN(r13)
>> + std r5,SOFTE(r1)
>> + mfdar r5
>> + std r5,_DAR(r1)
>> + mfdsisr r5
>> + std r5,_DSISR(r1)
>> +
>> + .global optprobe_template_op_address
>> +optprobe_template_op_address:
>> + /*
>> + * Parameters to optimized_callback():
>> + * 1. optimized_kprobe structure in r3
>> + */
>> + nop
>> + nop
>> + nop
>> + nop
>> + nop
>> + /* 2. pt_regs pointer in r4 */
>> + addi r4,r1,STACK_FRAME_OVERHEAD
>> +
>> + .global optprobe_template_call_handler
>> +optprobe_template_call_handler:
>> + /* Branch to optimized_callback() */
>> + nop
>> +
>> + /*
>> + * Parameters for instruction emulation:
>> + * 1. Pass SP in register r3.
>> + */
>> + addi r3,r1,STACK_FRAME_OVERHEAD
>> +
>> + .global optprobe_template_insn
>> +optprobe_template_insn:
>> + /* 2, Pass instruction to be emulated in r4 */
>> + nop
>> + nop
>> +
>> + .global optprobe_template_call_emulate
>> +optprobe_template_call_emulate:
>> + /* Branch to emulate_step() */
>> + nop
>> +
>> + /*
>> + * All done.
>> + * Now, 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,_CCR(r1)
>> + mtcr r5
>> + ld r5,_DAR(r1)
>> + mtdar r5
>> + ld r5,_DSISR(r1)
>> + mtdsisr r5
>> + REST_GPR(0,r1)
>> + REST_10GPRS(2,r1)
>> + REST_10GPRS(12,r1)
>> + REST_10GPRS(22,r1)
>> + /* Restore the previous SP */
>> + addi r1,r1,INT_FRAME_SIZE
>> +
>> + .global optprobe_template_ret
>> +optprobe_template_ret:
>> + /* ... and jump back from trampoline */
>> + nop
>> +
>> + .global optprobe_template_end
>> +optprobe_template_end:
>> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
>> index 3362299..0c6c2b0 100644
>> --- a/arch/powerpc/lib/sstep.c
>> +++ b/arch/powerpc/lib/sstep.c
>> @@ -618,6 +618,27 @@ static int __kprobes trap_compare(long v1, long v2)
>> }
>>
>> /*
>> + * Helper to check if a given instruction is a conditional branch
>> + * Derived from the conditional checks in analyse_instr()
>> + */
>> +bool __kprobes is_conditional_branch(unsigned int instr)
>> +{
>> + unsigned int opcode = instr >> 26;
>> +
>> + if (opcode == 16) /* bc, bca, bcl, bcla */
>> + return true;
>> + if (opcode == 19) {
>> + switch ((instr >> 1) & 0x3ff) {
>> + case 16: /* bclr, bclrl */
>> + case 528: /* bcctr, bcctrl */
>> + case 560: /* bctar, bctarl */
>> + return true;
>> + }
>> + }
>> + return false;
>> +}
>> +
>> +/*
>> * Elements of 32-bit rotate and mask instructions.
>> */
>> #define MASK32(mb, me) ((0xffffffffUL >> (mb)) + \
>> @@ -2018,3 +2039,4 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
>> regs->nip = truncate_if_32bit(regs->msr, regs->nip + 4);
>> return 1;
>> }
>> +
> This seems unneeded linefeed :)
:-) I will remove the extra line.
Thanks and Regards,
Anju
> Thank you,
>
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