[PATCH x86/mm 4/6] x86-64 ptrace get/putreg current task

Roland McGrath
2007-11-29T00:41:43Z

This generalizes the getreg and putreg functions so they can be used on the
current task, as well as on a task stopped in TASK_TRACED and switched off.
This lays the groundwork to share this code for all kinds of user-mode
machine state access, not just ptrace.

Signed-off-by: Roland McGrath <roland@redhat.com>
---
arch/x86/kernel/ptrace_64.c | 36 ++++++++++++++++++++++++++++++++++--
1 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/ptrace_64.c b/arch/x86/kernel/ptrace_64.c
index 2427548..5979dbe 100644
--- a/arch/x86/kernel/ptrace_64.c
+++ b/arch/x86/kernel/ptrace_64.c
@@ -67,21 +67,29 @@ static int putreg(struct task_struct *child,
if (value && (value & 3) != 3)
return -EIO;
child->thread.fsindex = value & 0xffff;
+ if (child == current)
+ loadsegment(fs, child->thread.fsindex);
return 0;
case offsetof(struct user_regs_struct,gs):
if (value && (value & 3) != 3)
return -EIO;
child->thread.gsindex = value & 0xffff;
+ if (child == current)
+ load_gs_index(child->thread.gsindex);
return 0;
case offsetof(struct user_regs_struct,ds):
if (value && (value & 3) != 3)
return -EIO;
child->thread.ds = value & 0xffff;
+ if (child == current)
+ loadsegment(ds, child->thread.ds);
return 0;
case offsetof(struct user_regs_struct,es):
if (value && (value & 3) != 3)
return -EIO;
child->thread.es = value & 0xffff;
+ if (child == current)
+ loadsegment(es, child->thread.es);
return 0;
case offsetof(struct user_regs_struct,ss):
if ((value & 3) != 3)
@@ -135,14 +143,32 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
{
struct pt_regs *regs = task_pt_regs(child);
unsigned long val;
+ unsigned int seg;
switch (regno) {
case offsetof(struct user_regs_struct, fs):
+ if (child == current) {
+ /* Older gas can't assemble movq %?s,%r?? */
+ asm("movl %%fs,%0" : "=r" (seg));
+ return seg;
+ }
return child->thread.fsindex;
case offsetof(struct user_regs_struct, gs):
+ if (child == current) {
+ asm("movl %%gs,%0" : "=r" (seg));
+ return seg;
+ }
return child->thread.gsindex;
case offsetof(struct user_regs_struct, ds):
+ if (child == current) {
+ asm("movl %%ds,%0" : "=r" (seg));
+ return seg;
+ }
return child->thread.ds;
case offsetof(struct user_regs_struct, es):
+ if (child == current) {
+ asm("movl %%es,%0" : "=r" (seg));
+ return seg;
+ }
return child->thread.es;
case offsetof(struct user_regs_struct, fs_base):
/*
@@ -152,7 +178,10 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
*/
if (child->thread.fs != 0)
return child->thread.fs;
- if (child->thread.fsindex != FS_TLS_SEL)
+ seg = child->thread.fsindex;
+ if (child == current)
+ asm("movl %%fs,%0" : "=r" (seg));
+ if (seg != FS_TLS_SEL)
return 0;
return get_desc_base(&child->thread.tls_array[FS_TLS]);
case offsetof(struct user_regs_struct, gs_base):
@@ -161,7 +190,10 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
*/
if (child->thread.gs != 0)
return child->thread.gs;
- if (child->thread.gsindex != GS_TLS_SEL)
+ seg = child->thread.gsindex;
+ if (child == current)
+ asm("movl %%gs,%0" : "=r" (seg));
+ if (seg != GS_TLS_SEL)
return 0;
return get_desc_base(&child->thread.tls_array[GS_TLS]);
case offsetof(struct user_regs_struct, flags):