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x86: x86-32 ptrace debugreg cleanup

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This cleans up the 32-bit ptrace code to separate the guts of the
debug register access from the implementation of PTRACE_PEEKUSR and
PTRACE_POKEUSR.  The new functions ptrace_[gs]et_debugreg match the
new 64-bit entry points for parity, but they don't need to be global.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Roland McGrath 2008-01-30 13:30:52 +01:00 committed by Ingo Molnar
parent d0f0817582
commit d9771e8c50
1 changed files with 69 additions and 50 deletions
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119
arch/x86/kernel/ptrace_32.c
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@ -118,6 +118,72 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
return retval;
}
/*
* This function is trivial and will be inlined by the compiler.
* Having it separates the implementation details of debug
* registers from the interface details of ptrace.
*/
static unsigned long ptrace_get_debugreg(struct task_struct *child, int n)
{
return child->thread.debugreg[n];
}
static int ptrace_set_debugreg(struct task_struct *child,
int n, unsigned long data)
{
if (unlikely(n == 4 || n == 5))
return -EIO;
if (n < 4 && unlikely(data >= TASK_SIZE - 3))
return -EIO;
if (n == 7) {
/*
* Sanity-check data. Take one half-byte at once with
* check = (val >> (16 + 4*i)) & 0xf. It contains the
* R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
* 2 and 3 are LENi. Given a list of invalid values,
* we do mask |= 1 << invalid_value, so that
* (mask >> check) & 1 is a correct test for invalid
* values.
*
* R/Wi contains the type of the breakpoint /
* watchpoint, LENi contains the length of the watched
* data in the watchpoint case.
*
* The invalid values are:
* - LENi == 0x10 (undefined), so mask |= 0x0f00.
* - R/Wi == 0x10 (break on I/O reads or writes), so
* mask |= 0x4444.
* - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
* 0x1110.
*
* Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
*
* See the Intel Manual "System Programming Guide",
* 15.2.4
*
* Note that LENi == 0x10 is defined on x86_64 in long
* mode (i.e. even for 32-bit userspace software, but
* 64-bit kernel), so the x86_64 mask value is 0x5454.
* See the AMD manual no. 24593 (AMD64 System Programming)
*/
int i;
data &= ~DR_CONTROL_RESERVED;
for (i = 0; i < 4; i++)
if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
return -EIO;
if (data)
set_tsk_thread_flag(child, TIF_DEBUG);
else
clear_tsk_thread_flag(child, TIF_DEBUG);
}
child->thread.debugreg[n] = data;
return 0;
}
/*
* Called by kernel/ptrace.c when detaching..
*
@ -158,7 +224,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
addr <= (long) &dummy->u_debugreg[7]){
addr -= (long) &dummy->u_debugreg[0];
addr = addr >> 2;
tmp = child->thread.debugreg[addr];
tmp = ptrace_get_debugreg(child, addr);
}
ret = put_user(tmp, datap);
break;
@ -188,56 +254,9 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
ret = -EIO;
if(addr >= (long) &dummy->u_debugreg[0] &&
addr <= (long) &dummy->u_debugreg[7]){
if(addr == (long) &dummy->u_debugreg[4]) break;
if(addr == (long) &dummy->u_debugreg[5]) break;
if(addr < (long) &dummy->u_debugreg[4] &&
((unsigned long) data) >= TASK_SIZE-3) break;
/* Sanity-check data. Take one half-byte at once with
* check = (val >> (16 + 4*i)) & 0xf. It contains the
* R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits
* 2 and 3 are LENi. Given a list of invalid values,
* we do mask |= 1 << invalid_value, so that
* (mask >> check) & 1 is a correct test for invalid
* values.
*
* R/Wi contains the type of the breakpoint /
* watchpoint, LENi contains the length of the watched
* data in the watchpoint case.
*
* The invalid values are:
* - LENi == 0x10 (undefined), so mask |= 0x0f00.
* - R/Wi == 0x10 (break on I/O reads or writes), so
* mask |= 0x4444.
* - R/Wi == 0x00 && LENi != 0x00, so we have mask |=
* 0x1110.
*
* Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54.
*
* See the Intel Manual "System Programming Guide",
* 15.2.4
*
* Note that LENi == 0x10 is defined on x86_64 in long
* mode (i.e. even for 32-bit userspace software, but
* 64-bit kernel), so the x86_64 mask value is 0x5454.
* See the AMD manual no. 24593 (AMD64 System
* Programming)*/
if(addr == (long) &dummy->u_debugreg[7]) {
data &= ~DR_CONTROL_RESERVED;
for(i=0; i<4; i++)
if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
goto out_tsk;
if (data)
set_tsk_thread_flag(child, TIF_DEBUG);
else
clear_tsk_thread_flag(child, TIF_DEBUG);
}
addr -= (long) &dummy->u_debugreg;
addr = addr >> 2;
child->thread.debugreg[addr] = data;
ret = 0;
ret = ptrace_set_debugreg(child, addr, data);
}
break;
@ -335,7 +354,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
ret = ptrace_request(child, request, addr, data);
break;
}
out_tsk:
return ret;
}