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28e6103665
So, forever, we've had this ptrace_signal_deliver implementation
which tries to handle all of the nasties that can occur when the
debugger looks at a process about to take a signal. It's meant
to address all of these issues inside of the kernel so that the
debugger need not be mindful of such things.
Problem is, this doesn't work.
The idea was that we should do the syscall restart business first, so
that the debugger captures that state. Otherwise, if the debugger for
example saves the child's state, makes the child execute something
else, then restores the saved state, we won't handle the syscall
restart properly because we lose the "we're in a syscall" state.
The code here worked for most cases, but if the debugger actually
passes the signal through to the child unaltered, it's possible that
we would do a syscall restart when we shouldn't have.
In particular this breaks the case of debugging a process under a gdb
which is being debugged by yet another gdb. gdb uses sigsuspend
to wait for SIGCHLD of the inferior, but if gdb itself is being
debugged by a top-level gdb we get a ptrace_stop(). The top-level gdb
does a PTRACE_CONT with SIGCHLD to let the inferior gdb see the
signal. But ptrace_signal_deliver() assumed the debugger would cancel
out the signal and therefore did a syscall restart, because the return
error was ERESTARTNOHAND.
Fix this by simply making ptrace_signal_deliver() a nop, and providing
a way for the debugger to control system call restarting properly:
1) Report a "in syscall" software bit in regs->{tstate,psr}.
It is set early on in trap entry to a system call and is fully
visible to the debugger via ptrace() and regsets.
2) Test this bit right before doing a syscall restart. We have
to do a final recheck right after get_signal_to_deliver() in
case the debugger cleared the bit during ptrace_stop().
3) Clear the bit in trap return so we don't accidently try to set
that bit in the real register.
As a result we also get a ptrace_{is,clear}_syscall() for sparc32 just
like sparc64 has.
M68K has this same exact bug, and is now the only other user of the
ptrace_signal_deliver hook. It needs to be fixed in the same exact
way as sparc.
Signed-off-by: David S. Miller <davem@davemloft.net>
175 lines
4.1 KiB
C
175 lines
4.1 KiB
C
/* $Id: ptrace.h,v 1.25 1997/03/04 16:27:25 jj Exp $ */
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#ifndef _SPARC_PTRACE_H
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#define _SPARC_PTRACE_H
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#include <asm/psr.h>
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/* This struct defines the way the registers are stored on the
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* stack during a system call and basically all traps.
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*/
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#ifndef __ASSEMBLY__
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struct pt_regs {
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unsigned long psr;
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unsigned long pc;
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unsigned long npc;
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unsigned long y;
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unsigned long u_regs[16]; /* globals and ins */
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};
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#define UREG_G0 0
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#define UREG_G1 1
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#define UREG_G2 2
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#define UREG_G3 3
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#define UREG_G4 4
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#define UREG_G5 5
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#define UREG_G6 6
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#define UREG_G7 7
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#define UREG_I0 8
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#define UREG_I1 9
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#define UREG_I2 10
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#define UREG_I3 11
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#define UREG_I4 12
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#define UREG_I5 13
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#define UREG_I6 14
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#define UREG_I7 15
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#define UREG_WIM UREG_G0
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#define UREG_FADDR UREG_G0
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#define UREG_FP UREG_I6
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#define UREG_RETPC UREG_I7
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static inline bool pt_regs_is_syscall(struct pt_regs *regs)
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{
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return (regs->psr & PSR_SYSCALL);
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}
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static inline bool pt_regs_clear_syscall(struct pt_regs *regs)
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{
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return (regs->psr &= ~PSR_SYSCALL);
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}
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/* A register window */
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struct reg_window {
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unsigned long locals[8];
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unsigned long ins[8];
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};
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/* A Sparc stack frame */
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struct sparc_stackf {
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unsigned long locals[8];
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unsigned long ins[6];
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struct sparc_stackf *fp;
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unsigned long callers_pc;
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char *structptr;
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unsigned long xargs[6];
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unsigned long xxargs[1];
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};
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#define TRACEREG_SZ sizeof(struct pt_regs)
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#define STACKFRAME_SZ sizeof(struct sparc_stackf)
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#ifdef __KERNEL__
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#define user_mode(regs) (!((regs)->psr & PSR_PS))
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#define instruction_pointer(regs) ((regs)->pc)
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unsigned long profile_pc(struct pt_regs *);
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extern void show_regs(struct pt_regs *);
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#endif
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#else /* __ASSEMBLY__ */
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/* For assembly code. */
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#define TRACEREG_SZ 0x50
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#define STACKFRAME_SZ 0x60
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#endif
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/*
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* The asm-offsets.h is a generated file, so we cannot include it.
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* It may be OK for glibc headers, but it's utterly pointless for C code.
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* The assembly code using those offsets has to include it explicitly.
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*/
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/* #include <asm/asm-offsets.h> */
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/* These are for pt_regs. */
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#define PT_PSR 0x0
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#define PT_PC 0x4
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#define PT_NPC 0x8
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#define PT_Y 0xc
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#define PT_G0 0x10
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#define PT_WIM PT_G0
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#define PT_G1 0x14
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#define PT_G2 0x18
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#define PT_G3 0x1c
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#define PT_G4 0x20
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#define PT_G5 0x24
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#define PT_G6 0x28
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#define PT_G7 0x2c
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#define PT_I0 0x30
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#define PT_I1 0x34
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#define PT_I2 0x38
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#define PT_I3 0x3c
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#define PT_I4 0x40
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#define PT_I5 0x44
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#define PT_I6 0x48
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#define PT_FP PT_I6
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#define PT_I7 0x4c
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/* Reg_window offsets */
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#define RW_L0 0x00
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#define RW_L1 0x04
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#define RW_L2 0x08
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#define RW_L3 0x0c
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#define RW_L4 0x10
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#define RW_L5 0x14
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#define RW_L6 0x18
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#define RW_L7 0x1c
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#define RW_I0 0x20
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#define RW_I1 0x24
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#define RW_I2 0x28
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#define RW_I3 0x2c
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#define RW_I4 0x30
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#define RW_I5 0x34
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#define RW_I6 0x38
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#define RW_I7 0x3c
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/* Stack_frame offsets */
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#define SF_L0 0x00
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#define SF_L1 0x04
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#define SF_L2 0x08
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#define SF_L3 0x0c
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#define SF_L4 0x10
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#define SF_L5 0x14
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#define SF_L6 0x18
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#define SF_L7 0x1c
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#define SF_I0 0x20
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#define SF_I1 0x24
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#define SF_I2 0x28
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#define SF_I3 0x2c
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#define SF_I4 0x30
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#define SF_I5 0x34
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#define SF_FP 0x38
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#define SF_PC 0x3c
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#define SF_RETP 0x40
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#define SF_XARG0 0x44
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#define SF_XARG1 0x48
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#define SF_XARG2 0x4c
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#define SF_XARG3 0x50
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#define SF_XARG4 0x54
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#define SF_XARG5 0x58
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#define SF_XXARG 0x5c
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/* Stuff for the ptrace system call */
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#define PTRACE_SPARC_DETACH 11
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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_READDATA 16
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#define PTRACE_WRITEDATA 17
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#define PTRACE_READTEXT 18
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#define PTRACE_WRITETEXT 19
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#define PTRACE_GETFPAREGS 20
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#define PTRACE_SETFPAREGS 21
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#endif /* !(_SPARC_PTRACE_H) */
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