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x86: x86 ptrace getreg/putreg merge
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This merges 64-bit support into the low-level register access
functions in arch/x86/kernel/ptrace.c, paving the way to share
this file between 32-bit and 64-bit builds.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Roland McGrath authored and Ingo Molnar committed Jan 30, 2008
1 parent 06ee1b6 commit 2047b08
Showing 1 changed file with 213 additions and 4 deletions.
217 changes: 213 additions & 4 deletions arch/x86/kernel/ptrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@
#include <asm/debugreg.h>
#include <asm/ldt.h>
#include <asm/desc.h>
#include <asm/prctl.h>
#include <asm/proto.h>

/*
* does not yet catch signals sent when the child dies.
Expand All @@ -40,6 +42,16 @@
X86_EFLAGS_DF | X86_EFLAGS_OF | \
X86_EFLAGS_RF | X86_EFLAGS_AC))

/*
* Determines whether a value may be installed in a segment register.
*/
static inline bool invalid_selector(u16 value)
{
return unlikely(value != 0 && (value & SEGMENT_RPL_MASK) != USER_RPL);
}

#ifdef CONFIG_X86_32

#define FLAG_MASK FLAG_MASK_32

static long *pt_regs_access(struct pt_regs *regs, unsigned long regno)
Expand Down Expand Up @@ -73,7 +85,7 @@ static int set_segment_reg(struct task_struct *task,
/*
* The value argument was already truncated to 16 bits.
*/
if (value && (value & 3) != 3)
if (invalid_selector(value))
return -EIO;

if (offset != offsetof(struct user_regs_struct, gs))
Expand All @@ -91,6 +103,142 @@ static int set_segment_reg(struct task_struct *task,
return 0;
}

static unsigned long debugreg_addr_limit(struct task_struct *task)
{
return TASK_SIZE - 3;
}

#else /* CONFIG_X86_64 */

#define FLAG_MASK (FLAG_MASK_32 | X86_EFLAGS_NT)

static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long offset)
{
BUILD_BUG_ON(offsetof(struct pt_regs, r15) != 0);
return &regs->r15 + (offset / sizeof(regs->r15));
}

static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
{
/*
* Returning the value truncates it to 16 bits.
*/
unsigned int seg;

switch (offset) {
case offsetof(struct user_regs_struct, fs):
if (task == current) {
/* Older gas can't assemble movq %?s,%r?? */
asm("movl %%fs,%0" : "=r" (seg));
return seg;
}
return task->thread.fsindex;
case offsetof(struct user_regs_struct, gs):
if (task == current) {
asm("movl %%gs,%0" : "=r" (seg));
return seg;
}
return task->thread.gsindex;
case offsetof(struct user_regs_struct, ds):
if (task == current) {
asm("movl %%ds,%0" : "=r" (seg));
return seg;
}
return task->thread.ds;
case offsetof(struct user_regs_struct, es):
if (task == current) {
asm("movl %%es,%0" : "=r" (seg));
return seg;
}
return task->thread.es;

case offsetof(struct user_regs_struct, cs):
case offsetof(struct user_regs_struct, ss):
break;
}
return *pt_regs_access(task_pt_regs(task), offset);
}

static int set_segment_reg(struct task_struct *task,
unsigned long offset, u16 value)
{
/*
* The value argument was already truncated to 16 bits.
*/
if (invalid_selector(value))
return -EIO;

switch (offset) {
case offsetof(struct user_regs_struct,fs):
/*
* If this is setting fs as for normal 64-bit use but
* setting fs_base has implicitly changed it, leave it.
*/
if ((value == FS_TLS_SEL && task->thread.fsindex == 0 &&
task->thread.fs != 0) ||
(value == 0 && task->thread.fsindex == FS_TLS_SEL &&
task->thread.fs == 0))
break;
task->thread.fsindex = value;
if (task == current)
loadsegment(fs, task->thread.fsindex);
break;
case offsetof(struct user_regs_struct,gs):
/*
* If this is setting gs as for normal 64-bit use but
* setting gs_base has implicitly changed it, leave it.
*/
if ((value == GS_TLS_SEL && task->thread.gsindex == 0 &&
task->thread.gs != 0) ||
(value == 0 && task->thread.gsindex == GS_TLS_SEL &&
task->thread.gs == 0))
break;
task->thread.gsindex = value;
if (task == current)
load_gs_index(task->thread.gsindex);
break;
case offsetof(struct user_regs_struct,ds):
task->thread.ds = value;
if (task == current)
loadsegment(ds, task->thread.ds);
break;
case offsetof(struct user_regs_struct,es):
task->thread.es = value;
if (task == current)
loadsegment(es, task->thread.es);
break;

/*
* Can't actually change these in 64-bit mode.
*/
case offsetof(struct user_regs_struct,cs):
#ifdef CONFIG_IA32_EMULATION
if (test_tsk_thread_flag(task, TIF_IA32))
task_pt_regs(task)->cs = value;
break;
#endif
case offsetof(struct user_regs_struct,ss):
#ifdef CONFIG_IA32_EMULATION
if (test_tsk_thread_flag(task, TIF_IA32))
task_pt_regs(task)->ss = value;
break;
#endif
}

return 0;
}

static unsigned long debugreg_addr_limit(struct task_struct *task)
{
#ifdef CONFIG_IA32_EMULATION
if (test_tsk_thread_flag(task, TIF_IA32))
return IA32_PAGE_OFFSET - 3;
#endif
return TASK_SIZE64 - 7;
}

#endif /* CONFIG_X86_32 */

static unsigned long get_flags(struct task_struct *task)
{
unsigned long retval = task_pt_regs(task)->flags;
Expand Down Expand Up @@ -137,6 +285,29 @@ static int putreg(struct task_struct *child,

case offsetof(struct user_regs_struct, flags):
return set_flags(child, value);

#ifdef CONFIG_X86_64
case offsetof(struct user_regs_struct,fs_base):
if (value >= TASK_SIZE_OF(child))
return -EIO;
/*
* When changing the segment base, use do_arch_prctl
* to set either thread.fs or thread.fsindex and the
* corresponding GDT slot.
*/
if (child->thread.fs != value)
return do_arch_prctl(child, ARCH_SET_FS, value);
return 0;
case offsetof(struct user_regs_struct,gs_base):
/*
* Exactly the same here as the %fs handling above.
*/
if (value >= TASK_SIZE_OF(child))
return -EIO;
if (child->thread.gs != value)
return do_arch_prctl(child, ARCH_SET_GS, value);
return 0;
#endif
}

*pt_regs_access(task_pt_regs(child), offset) = value;
Expand All @@ -156,6 +327,37 @@ static unsigned long getreg(struct task_struct *task, unsigned long offset)

case offsetof(struct user_regs_struct, flags):
return get_flags(task);

#ifdef CONFIG_X86_64
case offsetof(struct user_regs_struct, fs_base): {
/*
* do_arch_prctl may have used a GDT slot instead of
* the MSR. To userland, it appears the same either
* way, except the %fs segment selector might not be 0.
*/
unsigned int seg = task->thread.fsindex;
if (task->thread.fs != 0)
return task->thread.fs;
if (task == current)
asm("movl %%fs,%0" : "=r" (seg));
if (seg != FS_TLS_SEL)
return 0;
return get_desc_base(&task->thread.tls_array[FS_TLS]);
}
case offsetof(struct user_regs_struct, gs_base): {
/*
* Exactly the same here as the %fs handling above.
*/
unsigned int seg = task->thread.gsindex;
if (task->thread.gs != 0)
return task->thread.gs;
if (task == current)
asm("movl %%gs,%0" : "=r" (seg));
if (seg != GS_TLS_SEL)
return 0;
return get_desc_base(&task->thread.tls_array[GS_TLS]);
}
#endif
}

return *pt_regs_access(task_pt_regs(task), offset);
Expand Down Expand Up @@ -187,7 +389,7 @@ static int ptrace_set_debugreg(struct task_struct *child,
if (unlikely(n == 4 || n == 5))
return -EIO;

if (n < 4 && unlikely(data >= TASK_SIZE - 3))
if (n < 4 && unlikely(data >= debugreg_addr_limit(child)))
return -EIO;

switch (n) {
Expand All @@ -197,6 +399,8 @@ static int ptrace_set_debugreg(struct task_struct *child,
case 3: child->thread.debugreg3 = data; break;

case 6:
if ((data & ~0xffffffffUL) != 0)
return -EIO;
child->thread.debugreg6 = data;
break;

Expand All @@ -215,7 +419,7 @@ static int ptrace_set_debugreg(struct task_struct *child,
* data in the watchpoint case.
*
* The invalid values are:
* - LENi == 0x10 (undefined), so mask |= 0x0f00.
* - 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 |=
Expand All @@ -231,9 +435,14 @@ static int ptrace_set_debugreg(struct task_struct *child,
* 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 ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)
if ((DR7_MASK >> ((data >> (16 + 4*i)) & 0xf)) & 1)
return -EIO;
child->thread.debugreg7 = data;
if (data)
Expand Down

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