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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>
93 lines
4.8 KiB
C
93 lines
4.8 KiB
C
/* $Id: pstate.h,v 1.6 1997/06/25 07:39:45 jj Exp $ */
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#ifndef _SPARC64_PSTATE_H
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#define _SPARC64_PSTATE_H
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#include <linux/const.h>
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/* The V9 PSTATE Register (with SpitFire extensions).
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*
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* -----------------------------------------------------------------------
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* | Resv | IG | MG | CLE | TLE | MM | RED | PEF | AM | PRIV | IE | AG |
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* -----------------------------------------------------------------------
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* 63 12 11 10 9 8 7 6 5 4 3 2 1 0
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*/
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#define PSTATE_IG _AC(0x0000000000000800,UL) /* Interrupt Globals. */
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#define PSTATE_MG _AC(0x0000000000000400,UL) /* MMU Globals. */
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#define PSTATE_CLE _AC(0x0000000000000200,UL) /* Current Little Endian.*/
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#define PSTATE_TLE _AC(0x0000000000000100,UL) /* Trap Little Endian. */
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#define PSTATE_MM _AC(0x00000000000000c0,UL) /* Memory Model. */
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#define PSTATE_TSO _AC(0x0000000000000000,UL) /* MM: TotalStoreOrder */
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#define PSTATE_PSO _AC(0x0000000000000040,UL) /* MM: PartialStoreOrder */
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#define PSTATE_RMO _AC(0x0000000000000080,UL) /* MM: RelaxedMemoryOrder*/
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#define PSTATE_RED _AC(0x0000000000000020,UL) /* Reset Error Debug. */
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#define PSTATE_PEF _AC(0x0000000000000010,UL) /* Floating Point Enable.*/
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#define PSTATE_AM _AC(0x0000000000000008,UL) /* Address Mask. */
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#define PSTATE_PRIV _AC(0x0000000000000004,UL) /* Privilege. */
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#define PSTATE_IE _AC(0x0000000000000002,UL) /* Interrupt Enable. */
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#define PSTATE_AG _AC(0x0000000000000001,UL) /* Alternate Globals. */
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/* The V9 TSTATE Register (with SpitFire and Linux extensions).
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*
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* ---------------------------------------------------------------------
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* | Resv | GL | CCR | ASI | %pil | PSTATE | Resv | CWP |
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* ---------------------------------------------------------------------
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* 63 43 42 40 39 32 31 24 23 20 19 8 7 5 4 0
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*/
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#define TSTATE_GL _AC(0x0000070000000000,UL) /* Global reg level */
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#define TSTATE_CCR _AC(0x000000ff00000000,UL) /* Condition Codes. */
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#define TSTATE_XCC _AC(0x000000f000000000,UL) /* Condition Codes. */
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#define TSTATE_XNEG _AC(0x0000008000000000,UL) /* %xcc Negative. */
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#define TSTATE_XZERO _AC(0x0000004000000000,UL) /* %xcc Zero. */
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#define TSTATE_XOVFL _AC(0x0000002000000000,UL) /* %xcc Overflow. */
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#define TSTATE_XCARRY _AC(0x0000001000000000,UL) /* %xcc Carry. */
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#define TSTATE_ICC _AC(0x0000000f00000000,UL) /* Condition Codes. */
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#define TSTATE_INEG _AC(0x0000000800000000,UL) /* %icc Negative. */
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#define TSTATE_IZERO _AC(0x0000000400000000,UL) /* %icc Zero. */
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#define TSTATE_IOVFL _AC(0x0000000200000000,UL) /* %icc Overflow. */
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#define TSTATE_ICARRY _AC(0x0000000100000000,UL) /* %icc Carry. */
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#define TSTATE_ASI _AC(0x00000000ff000000,UL) /* AddrSpace ID. */
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#define TSTATE_PIL _AC(0x0000000000f00000,UL) /* %pil (Linux traps)*/
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#define TSTATE_PSTATE _AC(0x00000000000fff00,UL) /* PSTATE. */
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#define TSTATE_IG _AC(0x0000000000080000,UL) /* Interrupt Globals.*/
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#define TSTATE_MG _AC(0x0000000000040000,UL) /* MMU Globals. */
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#define TSTATE_CLE _AC(0x0000000000020000,UL) /* CurrLittleEndian. */
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#define TSTATE_TLE _AC(0x0000000000010000,UL) /* TrapLittleEndian. */
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#define TSTATE_MM _AC(0x000000000000c000,UL) /* Memory Model. */
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#define TSTATE_TSO _AC(0x0000000000000000,UL) /* MM: TSO */
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#define TSTATE_PSO _AC(0x0000000000004000,UL) /* MM: PSO */
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#define TSTATE_RMO _AC(0x0000000000008000,UL) /* MM: RMO */
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#define TSTATE_RED _AC(0x0000000000002000,UL) /* Reset Error Debug.*/
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#define TSTATE_PEF _AC(0x0000000000001000,UL) /* FPU Enable. */
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#define TSTATE_AM _AC(0x0000000000000800,UL) /* Address Mask. */
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#define TSTATE_PRIV _AC(0x0000000000000400,UL) /* Privilege. */
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#define TSTATE_IE _AC(0x0000000000000200,UL) /* Interrupt Enable. */
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#define TSTATE_AG _AC(0x0000000000000100,UL) /* Alternate Globals.*/
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#define TSTATE_SYSCALL _AC(0x0000000000000020,UL) /* in syscall trap */
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#define TSTATE_CWP _AC(0x000000000000001f,UL) /* Curr Win-Pointer. */
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/* Floating-Point Registers State Register.
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*
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* --------------------------------
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* | Resv | FEF | DU | DL |
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* --------------------------------
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* 63 3 2 1 0
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*/
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#define FPRS_FEF _AC(0x0000000000000004,UL) /* FPU Enable. */
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#define FPRS_DU _AC(0x0000000000000002,UL) /* Dirty Upper. */
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#define FPRS_DL _AC(0x0000000000000001,UL) /* Dirty Lower. */
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/* Version Register.
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*
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* ------------------------------------------------------
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* | MANUF | IMPL | MASK | Resv | MAXTL | Resv | MAXWIN |
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* ------------------------------------------------------
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* 63 48 47 32 31 24 23 16 15 8 7 5 4 0
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*/
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#define VERS_MANUF _AC(0xffff000000000000,UL) /* Manufacturer. */
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#define VERS_IMPL _AC(0x0000ffff00000000,UL) /* Implementation. */
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#define VERS_MASK _AC(0x00000000ff000000,UL) /* Mask Set Revision.*/
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#define VERS_MAXTL _AC(0x000000000000ff00,UL) /* Max Trap Level. */
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#define VERS_MAXWIN _AC(0x000000000000001f,UL) /* Max RegWindow Idx.*/
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#endif /* !(_SPARC64_PSTATE_H) */
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