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While in theory user_enable_single_step/user_disable_single_step/
user_enable_blockstep could also be provided as an inline or macro there's
no good reason to do so, and having the prototype in one places keeps code
size and confusion down.
Roland said:
The original thought there was that user_enable_single_step() et al
might well be only an instruction or three on a sane machine (as if we
have any of those!), and since there is only one call site inlining
would be beneficial. But I agree that there is no strong reason to care
about inlining it.
As to the arch changes, there is only one thought I'd add to the
record. It was always my thinking that for an arch where
PTRACE_SINGLESTEP does text-modifying breakpoint insertion,
user_enable_single_step() should not be provided. That is,
arch_has_single_step()=>true means that there is an arch facility with
"pure" semantics that does not have any unexpected side effects.
Inserting a breakpoint might do very unexpected strange things in
multi-threaded situations. Aside from that, it is a peculiar side
effect that user_{enable,disable}_single_step() should cause COW
de-sharing of text pages and so forth. For PTRACE_SINGLESTEP, all these
peculiarities are the status quo ante for that arch, so having
arch_ptrace() itself do those is one thing. But for building other
things in the future, it is nicer to have a uniform "pure" semantics
that arch-independent code can expect.
OTOH, all such arch issues are really up to the arch maintainer. As
of today, there is nothing but ptrace using user_enable_single_step() et
al so it's a distinction without a practical difference. If/when there
are other facilities that use user_enable_single_step() and might care,
the affected arch's can revisit the question when someone cares about
the quality of the arch support for said new facility.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
91 lines
2.7 KiB
C
91 lines
2.7 KiB
C
/* ptrace.h: ptrace() relevant definitions
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*
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* Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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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_PTRACE_H
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#define _ASM_PTRACE_H
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#include <asm/registers.h>
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#ifdef __KERNEL__
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#include <asm/irq_regs.h>
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#define in_syscall(regs) (((regs)->tbr & TBR_TT) == TBR_TT_TRAP0)
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#endif
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#define PT_PSR 0
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#define PT_ISR 1
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#define PT_CCR 2
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#define PT_CCCR 3
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#define PT_LR 4
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#define PT_LCR 5
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#define PT_PC 6
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#define PT__STATUS 7 /* exception status */
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#define PT_SYSCALLNO 8 /* syscall number or -1 */
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#define PT_ORIG_GR8 9 /* saved GR8 for signal handling */
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#define PT_GNER0 10
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#define PT_GNER1 11
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#define PT_IACC0H 12
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#define PT_IACC0L 13
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#define PT_GR(j) ( 14 + (j)) /* GRj for 0<=j<=63 */
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#define PT_FR(j) ( 78 + (j)) /* FRj for 0<=j<=63 */
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#define PT_FNER(j) (142 + (j)) /* FNERj for 0<=j<=1 */
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#define PT_MSR(j) (144 + (j)) /* MSRj for 0<=j<=2 */
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#define PT_ACC(j) (146 + (j)) /* ACCj for 0<=j<=7 */
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#define PT_ACCG(jklm) (154 + (jklm)) /* ACCGjklm for 0<=jklm<=1 (reads four regs per slot) */
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#define PT_FSR(j) (156 + (j)) /* FSRj for 0<=j<=0 */
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#define PT__GPEND 78
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#define PT__END 157
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#define PT_TBR PT_GR(0)
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#define PT_SP PT_GR(1)
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#define PT_FP PT_GR(2)
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#define PT_PREV_FRAME PT_GR(28) /* previous exception frame pointer (old gr28 value) */
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#define PT_CURR_TASK PT_GR(29) /* current task */
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/* Arbitrarily choose the same ptrace numbers as used by the Sparc code. */
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#define PTRACE_GETREGS 12
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#define PTRACE_SETREGS 13
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#define PTRACE_GETFPREGS 14
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#define PTRACE_SETFPREGS 15
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#define PTRACE_GETFDPIC 31 /* get the ELF fdpic loadmap address */
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#define PTRACE_GETFDPIC_EXEC 0 /* [addr] request the executable loadmap */
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#define PTRACE_GETFDPIC_INTERP 1 /* [addr] request the interpreter loadmap */
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#ifdef __KERNEL__
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#ifndef __ASSEMBLY__
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struct task_struct;
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/*
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* we dedicate GR28 to keeping a pointer to the current exception frame
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* - gr28 is destroyed on entry to the kernel from userspace
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*/
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register struct pt_regs *__frame asm("gr28");
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#define user_mode(regs) (!((regs)->psr & PSR_S))
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#define instruction_pointer(regs) ((regs)->pc)
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#define user_stack_pointer(regs) ((regs)->sp)
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extern unsigned long user_stack(const struct pt_regs *);
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extern void show_regs(struct pt_regs *);
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#define profile_pc(regs) ((regs)->pc)
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#define task_pt_regs(task) ((task)->thread.frame0)
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#define arch_has_single_step() (1)
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#endif /* !__ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_PTRACE_H */
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