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[PATCH] i386/x86-64: rename is_at_popf(), add iret to tests and fix
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>
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91cd444e56
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2 changed files with 10 additions and 12 deletions
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@ -185,17 +185,17 @@ static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_
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return addr;
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}
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static inline int is_at_popf(struct task_struct *child, struct pt_regs *regs)
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static inline int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
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{
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int i, copied;
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unsigned char opcode[16];
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unsigned char opcode[15];
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unsigned long addr = convert_eip_to_linear(child, regs);
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copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
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for (i = 0; i < copied; i++) {
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switch (opcode[i]) {
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/* popf */
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case 0x9d:
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/* popf and iret */
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case 0x9d: case 0xcf:
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return 1;
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/* opcode and address size prefixes */
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case 0x66: case 0x67:
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@ -247,7 +247,7 @@ static void set_singlestep(struct task_struct *child)
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* don't mark it as being "us" that set it, so that we
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* won't clear it by hand later.
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*/
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if (is_at_popf(child, regs))
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if (is_setting_trap_flag(child, regs))
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return;
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child->ptrace |= PT_DTRACE;
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@ -116,17 +116,17 @@ unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *r
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return addr;
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}
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static int is_at_popf(struct task_struct *child, struct pt_regs *regs)
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static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
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{
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int i, copied;
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unsigned char opcode[16];
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unsigned char opcode[15];
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unsigned long addr = convert_rip_to_linear(child, regs);
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copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
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for (i = 0; i < copied; i++) {
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switch (opcode[i]) {
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/* popf */
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case 0x9d:
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/* popf and iret */
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case 0x9d: case 0xcf:
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return 1;
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/* CHECKME: 64 65 */
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@ -189,10 +189,8 @@ static void set_singlestep(struct task_struct *child)
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* ..but if TF is changed by the instruction we will trace,
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* don't mark it as being "us" that set it, so that we
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* won't clear it by hand later.
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*
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* AK: this is not enough, LAHF and IRET can change TF in user space too.
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*/
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if (is_at_popf(child, regs))
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if (is_setting_trap_flag(child, regs))
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return;
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child->ptrace |= PT_DTRACE;
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