85101af13b
ABIv2 kernels are failing to backtrace through the kernel. An example:
39.30% readseek2_proce [kernel.kallsyms] [k] find_get_entry
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--- find_get_entry
__GI___libc_read
The problem is in valid_next_sp() where we check that the new stack
pointer is at least STACK_FRAME_OVERHEAD below the previous one.
ABIv1 has a minimum stack frame size of 112 bytes consisting of 48 bytes
and 64 bytes of parameter save area. ABIv2 changes that to 32 bytes
with no paramter save area.
STACK_FRAME_OVERHEAD is in theory the minimum stack frame size,
but we over 240 uses of it, some of which assume that it includes
space for the parameter area.
We need to work through all our stack defines and rationalise them
but let's fix perf now by creating STACK_FRAME_MIN_SIZE and using
in valid_next_sp(). This fixes the issue:
30.64% readseek2_proce [kernel.kallsyms] [k] find_get_entry
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--- find_get_entry
pagecache_get_page
generic_file_read_iter
new_sync_read
vfs_read
sys_read
syscall_exit
__GI___libc_read
Cc: stable@vger.kernel.org # 3.16+
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
227 lines
7.2 KiB
C
227 lines
7.2 KiB
C
/*
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* Copyright (C) 2001 PPC64 Team, IBM Corp
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*
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* This struct defines the way the registers are stored on the
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* kernel stack during a system call or other kernel entry.
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*
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* this should only contain volatile regs
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* since we can keep non-volatile in the thread_struct
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* should set this up when only volatiles are saved
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* by intr code.
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*
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* Since this is going on the stack, *CARE MUST BE TAKEN* to insure
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* that the overall structure is a multiple of 16 bytes in length.
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*
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* Note that the offsets of the fields in this struct correspond with
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* the PT_* values below. This simplifies arch/powerpc/kernel/ptrace.c.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_POWERPC_PTRACE_H
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#define _ASM_POWERPC_PTRACE_H
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#include <uapi/asm/ptrace.h>
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#ifdef __powerpc64__
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/*
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* Size of redzone that userspace is allowed to use below the stack
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* pointer. This is 288 in the 64-bit big-endian ELF ABI, and 512 in
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* the new ELFv2 little-endian ABI, so we allow the larger amount.
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*
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* For kernel code we allow a 288-byte redzone, in order to conserve
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* kernel stack space; gcc currently only uses 288 bytes, and will
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* hopefully allow explicit control of the redzone size in future.
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*/
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#define USER_REDZONE_SIZE 512
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#define KERNEL_REDZONE_SIZE 288
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#define STACK_FRAME_OVERHEAD 112 /* size of minimum stack frame */
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#define STACK_FRAME_LR_SAVE 2 /* Location of LR in stack frame */
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#define STACK_FRAME_REGS_MARKER ASM_CONST(0x7265677368657265)
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#define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + \
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STACK_FRAME_OVERHEAD + KERNEL_REDZONE_SIZE)
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#define STACK_FRAME_MARKER 12
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#if defined(_CALL_ELF) && _CALL_ELF == 2
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#define STACK_FRAME_MIN_SIZE 32
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#else
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#define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD
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#endif
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/* Size of dummy stack frame allocated when calling signal handler. */
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#define __SIGNAL_FRAMESIZE 128
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#define __SIGNAL_FRAMESIZE32 64
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#else /* __powerpc64__ */
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#define USER_REDZONE_SIZE 0
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#define KERNEL_REDZONE_SIZE 0
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#define STACK_FRAME_OVERHEAD 16 /* size of minimum stack frame */
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#define STACK_FRAME_LR_SAVE 1 /* Location of LR in stack frame */
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#define STACK_FRAME_REGS_MARKER ASM_CONST(0x72656773)
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#define STACK_INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
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#define STACK_FRAME_MARKER 2
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#define STACK_FRAME_MIN_SIZE STACK_FRAME_OVERHEAD
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/* Size of stack frame allocated when calling signal handler. */
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#define __SIGNAL_FRAMESIZE 64
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#endif /* __powerpc64__ */
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#ifndef __ASSEMBLY__
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#define GET_IP(regs) ((regs)->nip)
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#define GET_USP(regs) ((regs)->gpr[1])
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#define GET_FP(regs) (0)
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#define SET_FP(regs, val)
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#ifdef CONFIG_SMP
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extern unsigned long profile_pc(struct pt_regs *regs);
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#define profile_pc profile_pc
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#endif
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#include <asm-generic/ptrace.h>
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#define kernel_stack_pointer(regs) ((regs)->gpr[1])
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static inline int is_syscall_success(struct pt_regs *regs)
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{
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return !(regs->ccr & 0x10000000);
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}
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static inline long regs_return_value(struct pt_regs *regs)
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{
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if (is_syscall_success(regs))
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return regs->gpr[3];
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else
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return -regs->gpr[3];
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}
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#ifdef __powerpc64__
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#define user_mode(regs) ((((regs)->msr) >> MSR_PR_LG) & 0x1)
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#else
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#define user_mode(regs) (((regs)->msr & MSR_PR) != 0)
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#endif
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#define force_successful_syscall_return() \
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do { \
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set_thread_flag(TIF_NOERROR); \
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} while(0)
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struct task_struct;
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extern int ptrace_get_reg(struct task_struct *task, int regno,
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unsigned long *data);
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extern int ptrace_put_reg(struct task_struct *task, int regno,
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unsigned long data);
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#define current_pt_regs() \
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((struct pt_regs *)((unsigned long)current_thread_info() + THREAD_SIZE) - 1)
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/*
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* We use the least-significant bit of the trap field to indicate
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* whether we have saved the full set of registers, or only a
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* partial set. A 1 there means the partial set.
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* On 4xx we use the next bit to indicate whether the exception
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* is a critical exception (1 means it is).
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*/
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#define FULL_REGS(regs) (((regs)->trap & 1) == 0)
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#ifndef __powerpc64__
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#define IS_CRITICAL_EXC(regs) (((regs)->trap & 2) != 0)
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#define IS_MCHECK_EXC(regs) (((regs)->trap & 4) != 0)
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#define IS_DEBUG_EXC(regs) (((regs)->trap & 8) != 0)
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#endif /* ! __powerpc64__ */
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#define TRAP(regs) ((regs)->trap & ~0xF)
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#ifdef __powerpc64__
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#define NV_REG_POISON 0xdeadbeefdeadbeefUL
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#define CHECK_FULL_REGS(regs) BUG_ON(regs->trap & 1)
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#else
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#define NV_REG_POISON 0xdeadbeef
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#define CHECK_FULL_REGS(regs) \
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do { \
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if ((regs)->trap & 1) \
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printk(KERN_CRIT "%s: partial register set\n", __func__); \
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} while (0)
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#endif /* __powerpc64__ */
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#define arch_has_single_step() (1)
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#define arch_has_block_step() (!cpu_has_feature(CPU_FTR_601))
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#define ARCH_HAS_USER_SINGLE_STEP_INFO
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/*
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* kprobe-based event tracer support
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*/
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#include <linux/stddef.h>
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#include <linux/thread_info.h>
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extern int regs_query_register_offset(const char *name);
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extern const char *regs_query_register_name(unsigned int offset);
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#define MAX_REG_OFFSET (offsetof(struct pt_regs, dsisr))
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/**
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* regs_get_register() - get register value from its offset
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* @regs: pt_regs from which register value is gotten
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* @offset: offset number of the register.
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*
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* regs_get_register returns the value of a register whose offset from @regs.
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* The @offset is the offset of the register in struct pt_regs.
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* If @offset is bigger than MAX_REG_OFFSET, this returns 0.
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*/
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static inline unsigned long regs_get_register(struct pt_regs *regs,
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unsigned int offset)
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{
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if (unlikely(offset > MAX_REG_OFFSET))
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return 0;
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return *(unsigned long *)((unsigned long)regs + offset);
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}
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/**
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* regs_within_kernel_stack() - check the address in the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @addr: address which is checked.
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*
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* regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
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* If @addr is within the kernel stack, it returns true. If not, returns false.
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*/
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static inline bool regs_within_kernel_stack(struct pt_regs *regs,
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unsigned long addr)
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{
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return ((addr & ~(THREAD_SIZE - 1)) ==
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(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));
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}
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/**
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* regs_get_kernel_stack_nth() - get Nth entry of the stack
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* @regs: pt_regs which contains kernel stack pointer.
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* @n: stack entry number.
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*
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* regs_get_kernel_stack_nth() returns @n th entry of the kernel stack which
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* is specified by @regs. If the @n th entry is NOT in the kernel stack,
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* this returns 0.
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*/
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static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
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unsigned int n)
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{
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unsigned long *addr = (unsigned long *)kernel_stack_pointer(regs);
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addr += n;
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if (regs_within_kernel_stack(regs, (unsigned long)addr))
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return *addr;
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else
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return 0;
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}
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#endif /* __ASSEMBLY__ */
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#ifndef __powerpc64__
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#else /* __powerpc64__ */
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#define PT_FPSCR32 (PT_FPR0 + 2*32 + 1) /* each FP reg occupies 2 32-bit userspace slots */
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#define PT_VR0_32 164 /* each Vector reg occupies 4 slots in 32-bit */
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#define PT_VSCR_32 (PT_VR0 + 32*4 + 3)
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#define PT_VRSAVE_32 (PT_VR0 + 33*4)
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#define PT_VSR0_32 300 /* each VSR reg occupies 4 slots in 32-bit */
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#endif /* __powerpc64__ */
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#endif /* _ASM_POWERPC_PTRACE_H */
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