[PATCH x86/mm 05/11] x86 ptrace getreg/putreg merge

Roland McGrath
2007-11-29T12:00:37Z

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>
---
arch/x86/kernel/ptrace.c | 215 +++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 211 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index eaec75a..f42f8d2 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -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.
@@ -40,6 +42,14 @@
X86_EFLAGS_DF | X86_EFLAGS_OF | \
X86_EFLAGS_RF | X86_EFLAGS_AC))

+/*
+ * Determines whether a value may be installed in a segment register.
+ */
+#define invalid_selector(value) \
+ ((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)
@@ -73,7 +83,7 @@ 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))
@@ -91,6 +101,142 @@ 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;
@@ -137,6 +283,29 @@ 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;
@@ -156,6 +325,37 @@ 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);
@@ -187,7 +387,7 @@ 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) {
@@ -197,6 +397,8 @@ 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;

@@ -215,7 +417,7 @@ 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 |=
@@ -231,9 +433,14 @@ 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)