Proliferation of offsetof() for user_regs_struct is trimmed
down with the USER_REGS_OFFSET macro.

Signed-off-by: Chang S. Bae <chang.seok....@intel.com>
Cc: Andi Kleen <a...@linux.intel.com>
Cc: H. Peter Anvin <h...@zytor.com>
cc: Andy Lutomirski <l...@kernel.org>
---
 arch/x86/kernel/ptrace.c | 78 +++++++++++++++++++++++++-----------------------
 1 file changed, 40 insertions(+), 38 deletions(-)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index b2f0beb..d8a1e1b 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -149,6 +149,8 @@ static inline bool invalid_selector(u16 value)
        return unlikely(value != 0 && (value & SEGMENT_RPL_MASK) != USER_RPL);
 }
 
+#define USER_REGS_OFFSET(r) offsetof(struct user_regs_struct, r)
+
 #ifdef CONFIG_X86_32
 
 #define FLAG_MASK              FLAG_MASK_32
@@ -194,7 +196,7 @@ static u16 get_segment_reg(struct task_struct *task, 
unsigned long offset)
         * Returning the value truncates it to 16 bits.
         */
        unsigned int retval;
-       if (offset != offsetof(struct user_regs_struct, gs))
+       if (offset != USER_REGS_OFFSET(gs))
                retval = *pt_regs_access(task_pt_regs(task), offset);
        else {
                if (task == current)
@@ -224,8 +226,8 @@ static int set_segment_reg(struct task_struct *task,
         * safely use invalid selectors) from a kernel trap frame.
         */
        switch (offset) {
-       case offsetof(struct user_regs_struct, cs):
-       case offsetof(struct user_regs_struct, ss):
+       case USER_REGS_OFFSET(cs):
+       case USER_REGS_OFFSET(ss):
                if (unlikely(value == 0))
                        return -EIO;
 
@@ -233,7 +235,7 @@ static int set_segment_reg(struct task_struct *task,
                *pt_regs_access(task_pt_regs(task), offset) = value;
                break;
 
-       case offsetof(struct user_regs_struct, gs):
+       case USER_REGS_OFFSET(gs):
                if (task == current)
                        set_user_gs(task_pt_regs(task), value);
                else
@@ -261,34 +263,34 @@ static u16 get_segment_reg(struct task_struct *task, 
unsigned long offset)
        unsigned int seg;
 
        switch (offset) {
-       case offsetof(struct user_regs_struct, fs):
+       case USER_REGS_OFFSET(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):
+       case USER_REGS_OFFSET(gs):
                if (task == current) {
                        asm("movl %%gs,%0" : "=r" (seg));
                        return seg;
                }
                return task->thread.gsindex;
-       case offsetof(struct user_regs_struct, ds):
+       case USER_REGS_OFFSET(ds):
                if (task == current) {
                        asm("movl %%ds,%0" : "=r" (seg));
                        return seg;
                }
                return task->thread.ds;
-       case offsetof(struct user_regs_struct, es):
+       case USER_REGS_OFFSET(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):
+       case USER_REGS_OFFSET(cs):
+       case USER_REGS_OFFSET(ss):
                break;
        }
        return *pt_regs_access(task_pt_regs(task), offset);
@@ -304,22 +306,22 @@ static int set_segment_reg(struct task_struct *task,
                return -EIO;
 
        switch (offset) {
-       case offsetof(struct user_regs_struct,fs):
+       case USER_REGS_OFFSET(fs):
                task->thread.fsindex = value;
                if (task == current)
                        loadsegment(fs, task->thread.fsindex);
                break;
-       case offsetof(struct user_regs_struct,gs):
+       case USER_REGS_OFFSET(gs):
                task->thread.gsindex = value;
                if (task == current)
                        load_gs_index(task->thread.gsindex);
                break;
-       case offsetof(struct user_regs_struct,ds):
+       case USER_REGS_OFFSET(ds):
                task->thread.ds = value;
                if (task == current)
                        loadsegment(ds, task->thread.ds);
                break;
-       case offsetof(struct user_regs_struct,es):
+       case USER_REGS_OFFSET(es):
                task->thread.es = value;
                if (task == current)
                        loadsegment(es, task->thread.es);
@@ -328,12 +330,12 @@ static int set_segment_reg(struct task_struct *task,
                /*
                 * Can't actually change these in 64-bit mode.
                 */
-       case offsetof(struct user_regs_struct,cs):
+       case USER_REGS_OFFSET(cs):
                if (unlikely(value == 0))
                        return -EIO;
                task_pt_regs(task)->cs = value;
                break;
-       case offsetof(struct user_regs_struct,ss):
+       case USER_REGS_OFFSET(ss):
                if (unlikely(value == 0))
                        return -EIO;
                task_pt_regs(task)->ss = value;
@@ -381,19 +383,19 @@ static int putreg(struct task_struct *child,
                  unsigned long offset, unsigned long value)
 {
        switch (offset) {
-       case offsetof(struct user_regs_struct, cs):
-       case offsetof(struct user_regs_struct, ds):
-       case offsetof(struct user_regs_struct, es):
-       case offsetof(struct user_regs_struct, fs):
-       case offsetof(struct user_regs_struct, gs):
-       case offsetof(struct user_regs_struct, ss):
+       case USER_REGS_OFFSET(cs):
+       case USER_REGS_OFFSET(ds):
+       case USER_REGS_OFFSET(es):
+       case USER_REGS_OFFSET(fs):
+       case USER_REGS_OFFSET(gs):
+       case USER_REGS_OFFSET(ss):
                return set_segment_reg(child, offset, value);
 
-       case offsetof(struct user_regs_struct, flags):
+       case USER_REGS_OFFSET(flags):
                return set_flags(child, value);
 
 #ifdef CONFIG_X86_64
-       case offsetof(struct user_regs_struct,fs_base):
+       case USER_REGS_OFFSET(fs_base):
                if (value >= TASK_SIZE_MAX)
                        return -EIO;
                /*
@@ -403,7 +405,7 @@ static int putreg(struct task_struct *child,
                if (child->thread.fsbase != value)
                        return write_task_fsbase(child, value);
                return 0;
-       case offsetof(struct user_regs_struct,gs_base):
+       case USER_REGS_OFFSET(gs_base):
                /*
                 * Exactly the same here as the %fs handling above.
                 */
@@ -422,21 +424,21 @@ static int putreg(struct task_struct *child,
 static unsigned long getreg(struct task_struct *task, unsigned long offset)
 {
        switch (offset) {
-       case offsetof(struct user_regs_struct, cs):
-       case offsetof(struct user_regs_struct, ds):
-       case offsetof(struct user_regs_struct, es):
-       case offsetof(struct user_regs_struct, fs):
-       case offsetof(struct user_regs_struct, gs):
-       case offsetof(struct user_regs_struct, ss):
+       case USER_REGS_OFFSET(cs):
+       case USER_REGS_OFFSET(ds):
+       case USER_REGS_OFFSET(es):
+       case USER_REGS_OFFSET(fs):
+       case USER_REGS_OFFSET(gs):
+       case USER_REGS_OFFSET(ss):
                return get_segment_reg(task, offset);
 
-       case offsetof(struct user_regs_struct, flags):
+       case USER_REGS_OFFSET(flags):
                return get_flags(task);
 
 #ifdef CONFIG_X86_64
-       case offsetof(struct user_regs_struct, fs_base):
+       case USER_REGS_OFFSET(fs_base):
                return read_task_fsbase(task);
-       case offsetof(struct user_regs_struct, gs_base):
+       case USER_REGS_OFFSET(gs_base):
                return read_task_gsbase(task);
 #endif
        }
@@ -885,7 +887,7 @@ long arch_ptrace(struct task_struct *child, long request,
 #define SEG32(rs)                                                      \
        case offsetof(struct user32, regs.rs):                          \
                return set_segment_reg(child,                           \
-                                      offsetof(struct user_regs_struct, rs), \
+                                      USER_REGS_OFFSET(rs), \
                                       value);                          \
                break
 
@@ -959,7 +961,7 @@ static int putreg32(struct task_struct *child, unsigned 
regno, u32 value)
 #define SEG32(rs)                                                      \
        case offsetof(struct user32, regs.rs):                          \
                *val = get_segment_reg(child,                           \
-                                      offsetof(struct user_regs_struct, rs)); \
+                                      USER_REGS_OFFSET(rs)); \
                break
 
 static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
@@ -1153,7 +1155,7 @@ static long x32_arch_ptrace(struct task_struct *child,
 
                ret = -EIO;
                if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) 
||
-                   addr < offsetof(struct user_regs_struct, cs))
+                   addr < USER_REGS_OFFSET(cs))
                        break;
 
                tmp = 0;  /* Default return condition */
@@ -1174,7 +1176,7 @@ static long x32_arch_ptrace(struct task_struct *child,
        case PTRACE_POKEUSR:
                ret = -EIO;
                if ((addr & (sizeof(data) - 1)) || addr >= sizeof(struct user) 
||
-                   addr < offsetof(struct user_regs_struct, cs))
+                   addr < USER_REGS_OFFSET(cs))
                        break;
 
                if (addr < sizeof(struct user_regs_struct))
-- 
2.7.4

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