[PATCH 5/5] uprobes/x86: Move default_xol_ops's data into arch_uprobe->def

From: Oleg Nesterov
Date: Tue Apr 22 2014 - 10:49:01 EST

Finally we can move arch_uprobe->fixups/rip_rela_target_address
into the new "def" struct and place this struct in the union, they
are only used by default_xol_ops paths.

The patch also renames rip_rela_target_address to riprel_target just
to make this name shorter.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
arch/x86/include/asm/uprobes.h | 12 ++++++----
arch/x86/kernel/uprobes.c | 41 +++++++++++++++++++--------------------
2 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index 93bee7b..72caff7 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -41,18 +41,20 @@ struct arch_uprobe {
u8 ixol[MAX_UINSN_BYTES];
};

- u16 fixups;
const struct uprobe_xol_ops *ops;

union {
-#ifdef CONFIG_X86_64
- unsigned long rip_rela_target_address;
-#endif
struct {
s32 offs;
u8 ilen;
u8 opc1;
- } branch;
+ } branch;
+ struct {
+#ifdef CONFIG_X86_64
+ long riprel_target;
+#endif
+ u16 fixups;
+ } def;
};
};

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index e6314a2..69b2d61 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -251,10 +251,9 @@ static inline bool is_64bit_mm(struct mm_struct *mm)
* If arch_uprobe->insn doesn't use rip-relative addressing, return
* immediately. Otherwise, rewrite the instruction so that it accesses
* its memory operand indirectly through a scratch register. Set
- * arch_uprobe->fixups and arch_uprobe->rip_rela_target_address
- * accordingly. (The contents of the scratch register will be saved
- * before we single-step the modified instruction, and restored
- * afterward.)
+ * def->fixups and def->riprel_target accordingly. (The contents of the
+ * scratch register will be saved before we single-step the modified
+ * instruction, and restored afterward).
*
* We do this because a rip-relative instruction can access only a
* relatively small area (+/- 2 GB from the instruction), and the XOL
@@ -308,18 +307,18 @@ handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)
* is NOT the register operand, so we use %rcx (register
* #1) for the scratch register.
*/
- auprobe->fixups = UPROBE_FIX_RIP_CX;
+ auprobe->def.fixups = UPROBE_FIX_RIP_CX;
/* Change modrm from 00 000 101 to 00 000 001. */
*cursor = 0x1;
} else {
/* Use %rax (register #0) for the scratch register. */
- auprobe->fixups = UPROBE_FIX_RIP_AX;
+ auprobe->def.fixups = UPROBE_FIX_RIP_AX;
/* Change modrm from 00 xxx 101 to 00 xxx 000 */
*cursor = (reg << 3);
}

/* Target address = address of next instruction + (signed) offset */
- auprobe->rip_rela_target_address = (long)insn->length + insn->displacement.value;
+ auprobe->def.riprel_target = (long)insn->length + insn->displacement.value;

/* Displacement field is gone; slide immediate field (if any) over. */
if (insn->immediate.nbytes) {
@@ -336,25 +335,25 @@ static void
pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
struct arch_uprobe_task *autask)
{
- if (auprobe->fixups & UPROBE_FIX_RIP_AX) {
+ if (auprobe->def.fixups & UPROBE_FIX_RIP_AX) {
autask->saved_scratch_register = regs->ax;
regs->ax = current->utask->vaddr;
- regs->ax += auprobe->rip_rela_target_address;
- } else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {
+ regs->ax += auprobe->def.riprel_target;
+ } else if (auprobe->def.fixups & UPROBE_FIX_RIP_CX) {
autask->saved_scratch_register = regs->cx;
regs->cx = current->utask->vaddr;
- regs->cx += auprobe->rip_rela_target_address;
+ regs->cx += auprobe->def.riprel_target;
}
}

static void
handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
{
- if (auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
+ if (auprobe->def.fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
struct arch_uprobe_task *autask;

autask = &current->utask->autask;
- if (auprobe->fixups & UPROBE_FIX_RIP_AX)
+ if (auprobe->def.fixups & UPROBE_FIX_RIP_AX)
regs->ax = autask->saved_scratch_register;
else
regs->cx = autask->saved_scratch_register;
@@ -432,17 +431,17 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs
long correction = (long)(utask->vaddr - utask->xol_vaddr);

handle_riprel_post_xol(auprobe, regs, &correction);
- if (auprobe->fixups & UPROBE_FIX_IP)
+ if (auprobe->def.fixups & UPROBE_FIX_IP)
regs->ip += correction;

- if (auprobe->fixups & UPROBE_FIX_CALL) {
+ if (auprobe->def.fixups & UPROBE_FIX_CALL) {
if (adjust_ret_addr(regs->sp, correction)) {
regs->sp += sizeof_long();
return -ERESTART;
}
}
/* popf; tell the caller to not touch TF */
- if (auprobe->fixups & UPROBE_FIX_SETF)
+ if (auprobe->def.fixups & UPROBE_FIX_SETF)
utask->autask.saved_tf = true;

return 0;
@@ -636,12 +635,12 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,

/*
* Figure out which fixups arch_uprobe_post_xol() will need to perform,
- * and annotate arch_uprobe->fixups accordingly. To start with, ->fixups
- * is either zero or it reflects rip-related fixups.
+ * and annotate def->fixups accordingly. To start with, ->fixups is
+ * either zero or it reflects rip-related fixups.
*/
switch (OPCODE1(&insn)) {
case 0x9d: /* popf */
- auprobe->fixups |= UPROBE_FIX_SETF;
+ auprobe->def.fixups |= UPROBE_FIX_SETF;
break;
case 0xc3: /* ret or lret -- ip is correct */
case 0xcb:
@@ -669,9 +668,9 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
}

if (fix_ip)
- auprobe->fixups |= UPROBE_FIX_IP;
+ auprobe->def.fixups |= UPROBE_FIX_IP;
if (fix_call)
- auprobe->fixups |= UPROBE_FIX_CALL;
+ auprobe->def.fixups |= UPROBE_FIX_CALL;

auprobe->ops = &default_xol_ops;
return 0;
--
1.5.5.1

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