[PATCH for review] [103/145] i386/x86-64: rename is_at_popf(), add iret to tests and fix

Andi Kleen
2006-08-10T19:50:18Z

r

From: Chuck Ebbert <76306.1226@compuserve.com>

is_at_popf() needs to test for the iret instruction as well as
popf. So add that test and rename it to is_setting_trap_flag().

Also change max insn length from 16 to 15 to match reality.

LAHF / SAHF can't affect TF, so the comment in x86_64 is removed.

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andi Kleen <ak@suse.de>

---

Tested on x86_64.

---
arch/i386/kernel/ptrace.c | 10 +++++-----
arch/x86_64/kernel/ptrace.c | 12 +++++-------
2 files changed, 10 insertions(+), 12 deletions(-)

Index: linux/arch/i386/kernel/ptrace.c
===================================================================
--- linux.orig/arch/i386/kernel/ptrace.c
+++ linux/arch/i386/kernel/ptrace.c
@@ -185,17 +185,17 @@ static unsigned long convert_eip_to_line
return addr;
}

-static inline int is_at_popf(struct task_struct *child, struct pt_regs *regs)
+static inline int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
{
int i, copied;
- unsigned char opcode[16];
+ unsigned char opcode[15];
unsigned long addr = convert_eip_to_linear(child, regs);

copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
for (i = 0; i < copied; i++) {
switch (opcode[i]) {
- /* popf */
- case 0x9d:
+ /* popf and iret */
+ case 0x9d: case 0xcf:
return 1;
/* opcode and address size prefixes */
case 0x66: case 0x67:
@@ -247,7 +247,7 @@ static void set_singlestep(struct task_s
* don't mark it as being "us" that set it, so that we
* won't clear it by hand later.
*/
- if (is_at_popf(child, regs))
+ if (is_setting_trap_flag(child, regs))
return;

child->ptrace |= PT_DTRACE;
Index: linux/arch/x86_64/kernel/ptrace.c
===================================================================
--- linux.orig/arch/x86_64/kernel/ptrace.c
+++ linux/arch/x86_64/kernel/ptrace.c
@@ -116,17 +116,17 @@ unsigned long convert_rip_to_linear(stru
return addr;
}

-static int is_at_popf(struct task_struct *child, struct pt_regs *regs)
+static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
{
int i, copied;
- unsigned char opcode[16];
+ unsigned char opcode[15];
unsigned long addr = convert_rip_to_linear(child, regs);

copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
for (i = 0; i < copied; i++) {
switch (opcode[i]) {
- /* popf */
- case 0x9d:
+ /* popf and iret */
+ case 0x9d: case 0xcf:
return 1;

/* CHECKME: 64 65 */
@@ -189,10 +189,8 @@ static void set_singlestep(struct task_s
* ..but if TF is changed by the instruction we will trace,
* don't mark it as being "us" that set it, so that we
* won't clear it by hand later.
- *
- * AK: this is not enough, LAHF and IRET can change TF in user space too.
*/
- if (is_at_popf(child, regs))
+ if (is_setting_trap_flag(child, regs))
return;

child->ptrace |= PT_DTRACE;