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Subject[RFC Patch 8/9] Modify Ptrace to use wrapper routines to access breakpoint registers
This patch modifies the ptrace code to use the new wrapper routines around the 
debug/breakpoint registers.

Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
---
arch/x86/kernel/ptrace.c | 101 +----------------------------------------------
1 file changed, 4 insertions(+), 97 deletions(-)

Index: linux-bkpt-lkml-27-rc9/arch/x86/kernel/ptrace.c
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/arch/x86/kernel/ptrace.c
+++ linux-bkpt-lkml-27-rc9/arch/x86/kernel/ptrace.c
@@ -462,98 +462,6 @@ static int genregs_set(struct task_struc
return ret;
}

-/*
- * 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)
-{
- switch (n) {
- case 0: return child->thread.debugreg0;
- case 1: return child->thread.debugreg1;
- case 2: return child->thread.debugreg2;
- case 3: return child->thread.debugreg3;
- case 6: return child->thread.debugreg6;
- case 7: return child->thread.debugreg7;
- }
- return 0;
-}
-
-static int ptrace_set_debugreg(struct task_struct *child,
- int n, unsigned long data)
-{
- int i;
-
- if (unlikely(n == 4 || n == 5))
- return -EIO;
-
- if (n < 4 && unlikely(data >= debugreg_addr_limit(child)))
- return -EIO;
-
- switch (n) {
- case 0: child->thread.debugreg0 = data; break;
- case 1: child->thread.debugreg1 = data; break;
- case 2: child->thread.debugreg2 = data; break;
- case 3: child->thread.debugreg3 = data; break;
-
- case 6:
- if ((data & ~0xffffffffUL) != 0)
- return -EIO;
- child->thread.debugreg6 = data;
- break;
-
- case 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. [32-bit]
- * - 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)
- */
-#ifdef CONFIG_X86_32
-#define DR7_MASK 0x5f54
-#else
-#define DR7_MASK 0x5554
-#endif
- data &= ~DR_CONTROL_RESERVED;
- for (i = 0; i < 4; i++)
- if ((DR7_MASK >> ((data >> (16 + 4*i)) & 0xf)) & 1)
- return -EIO;
- child->thread.debugreg7 = data;
- if (data)
- set_tsk_thread_flag(child, TIF_DEBUG);
- else
- clear_tsk_thread_flag(child, TIF_DEBUG);
- break;
- }
-
- return 0;
-}
-
#ifdef X86_BTS

static int ptrace_bts_get_size(struct task_struct *child)
@@ -888,7 +796,7 @@ long arch_ptrace(struct task_struct *chi
else if (addr >= offsetof(struct user, u_debugreg[0]) &&
addr <= offsetof(struct user, u_debugreg[7])) {
addr -= offsetof(struct user, u_debugreg[0]);
- tmp = ptrace_get_debugreg(child, addr / sizeof(data));
+ tmp = thread_get_debugreg(child, addr/sizeof(data));
}
ret = put_user(tmp, datap);
break;
@@ -905,8 +813,7 @@ long arch_ptrace(struct task_struct *chi
else if (addr >= offsetof(struct user, u_debugreg[0]) &&
addr <= offsetof(struct user, u_debugreg[7])) {
addr -= offsetof(struct user, u_debugreg[0]);
- ret = ptrace_set_debugreg(child,
- addr / sizeof(data), data);
+ ret = thread_set_debugreg(child, addr/sizeof(data), data);
}
break;

@@ -1073,7 +980,7 @@ static int putreg32(struct task_struct *
case offsetof(struct user32, u_debugreg[0]) ...
offsetof(struct user32, u_debugreg[7]):
regno -= offsetof(struct user32, u_debugreg[0]);
- return ptrace_set_debugreg(child, regno / 4, value);
+ return thread_set_debugreg(child, regno / 4, value);

default:
if (regno > sizeof(struct user32) || (regno & 3))
@@ -1132,7 +1039,7 @@ static int getreg32(struct task_struct *
case offsetof(struct user32, u_debugreg[0]) ...
offsetof(struct user32, u_debugreg[7]):
regno -= offsetof(struct user32, u_debugreg[0]);
- *val = ptrace_get_debugreg(child, regno / 4);
+ *val = thread_get_debugreg(child, regno / 4);
break;

default:

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