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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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dacbe41f77
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>
109 lines
2.7 KiB
C
109 lines
2.7 KiB
C
/* MN10300 Exception frame layout and ptrace constants
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*
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* Copyright (C) 2007 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 Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, 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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#define PT_A3 0
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#define PT_A2 1
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#define PT_D3 2
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#define PT_D2 3
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#define PT_MCVF 4
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#define PT_MCRL 5
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#define PT_MCRH 6
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#define PT_MDRQ 7
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#define PT_E1 8
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#define PT_E0 9
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#define PT_E7 10
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#define PT_E6 11
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#define PT_E5 12
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#define PT_E4 13
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#define PT_E3 14
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#define PT_E2 15
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#define PT_SP 16
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#define PT_LAR 17
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#define PT_LIR 18
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#define PT_MDR 19
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#define PT_A1 20
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#define PT_A0 21
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#define PT_D1 22
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#define PT_D0 23
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#define PT_ORIG_D0 24
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#define PT_EPSW 25
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#define PT_PC 26
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#define NR_PTREGS 27
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#ifndef __ASSEMBLY__
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/*
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* This defines the way registers are stored in the event of an exception
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* - the strange order is due to the MOVM instruction
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*/
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struct pt_regs {
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unsigned long a3; /* syscall arg 3 */
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unsigned long a2; /* syscall arg 4 */
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unsigned long d3; /* syscall arg 5 */
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unsigned long d2; /* syscall arg 6 */
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unsigned long mcvf;
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unsigned long mcrl;
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unsigned long mcrh;
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unsigned long mdrq;
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unsigned long e1;
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unsigned long e0;
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unsigned long e7;
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unsigned long e6;
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unsigned long e5;
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unsigned long e4;
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unsigned long e3;
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unsigned long e2;
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unsigned long sp;
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unsigned long lar;
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unsigned long lir;
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unsigned long mdr;
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unsigned long a1;
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unsigned long a0; /* syscall arg 1 */
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unsigned long d1; /* syscall arg 2 */
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unsigned long d0; /* syscall ret */
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struct pt_regs *next; /* next frame pointer */
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unsigned long orig_d0; /* syscall number */
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unsigned long epsw;
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unsigned long pc;
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};
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#endif
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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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/* options set using PTRACE_SETOPTIONS */
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#define PTRACE_O_TRACESYSGOOD 0x00000001
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#if defined(__KERNEL__)
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extern struct pt_regs *__frame; /* current frame pointer */
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#if !defined(__ASSEMBLY__)
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struct task_struct;
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#define user_mode(regs) (((regs)->epsw & EPSW_nSL) == EPSW_nSL)
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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 void show_regs(struct pt_regs *);
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#define arch_has_single_step() (1)
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#endif /* !__ASSEMBLY */
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#define profile_pc(regs) ((regs)->pc)
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#endif /* __KERNEL__ */
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#endif /* _ASM_PTRACE_H */
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