[patch 15/21] ptrace changes

From: Martin Schwidefsky
Date: Wed Oct 01 2008 - 05:02:17 EST

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From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>

* System call parameter and result access functions
* Add tracehook calls
* Split syscall_trace into two functions do_syscall_trace_enter and
do_syscall_trace_exit

Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
---

arch/s390/Kconfig | 1
arch/s390/include/asm/ptrace.h | 1
arch/s390/include/asm/syscall.h | 80 ++++++++++++++++++++++++++++++++++++
arch/s390/include/asm/thread_info.h | 2
arch/s390/kernel/entry.S | 50 ++++++++++++++++++----
arch/s390/kernel/entry64.S | 42 ++++++++++++++----
arch/s390/kernel/ptrace.c | 61 ++++++++++++++-------------
arch/s390/kernel/signal.c | 13 +++++
8 files changed, 202 insertions(+), 48 deletions(-)

Index: quilt-2.6/arch/s390/include/asm/ptrace.h
===================================================================
--- quilt-2.6.orig/arch/s390/include/asm/ptrace.h
+++ quilt-2.6/arch/s390/include/asm/ptrace.h
@@ -490,6 +490,7 @@ extern void user_disable_single_step(str

#define user_mode(regs) (((regs)->psw.mask & PSW_MASK_PSTATE) != 0)
#define instruction_pointer(regs) ((regs)->psw.addr & PSW_ADDR_INSN)
+#define user_stack_pointer(regs)((regs)->gprs[15])
#define regs_return_value(regs)((regs)->gprs[2])
#define profile_pc(regs) instruction_pointer(regs)
extern void show_regs(struct pt_regs * regs);
Index: quilt-2.6/arch/s390/include/asm/syscall.h
===================================================================
--- /dev/null
+++ quilt-2.6/arch/s390/include/asm/syscall.h
@@ -0,0 +1,80 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * Copyright IBM Corp. 2008
+ * Author(s): Martin Schwidefsky (schwidefsky@xxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_SYSCALL_H
+#define _ASM_SYSCALL_H 1
+
+#include <asm/ptrace.h>
+
+static inline long syscall_get_nr(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ if (regs->trap != __LC_SVC_OLD_PSW)
+ return -1;
+ return regs->gprs[2];
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ regs->gprs[2] = regs->orig_gpr2;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ return (regs->gprs[2] >= -4096UL) ? -regs->gprs[2] : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ return regs->gprs[2];
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+ struct pt_regs *regs,
+ int error, long val)
+{
+ regs->gprs[2] = error ? -error : val;
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned int i, unsigned int n,
+ unsigned long *args)
+{
+ BUG_ON(i + n > 6);
+#ifdef CONFIG_COMPAT
+ if (test_tsk_thread_flag(task, TIF_31BIT)) {
+ if (i + n == 6)
+ args[--n] = (u32) regs->args[0];
+ while (n-- > 0)
+ args[n] = (u32) regs->gprs[2 + i + n];
+ }
+#endif
+ if (i + n == 6)
+ args[--n] = regs->args[0];
+ memcpy(args, &regs->gprs[2 + i], n * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned int i, unsigned int n,
+ const unsigned long *args)
+{
+ BUG_ON(i + n > 6);
+ if (i + n == 6)
+ regs->args[0] = args[--n];
+ memcpy(&regs->gprs[2 + i], args, n * sizeof(args[0]));
+}
+
+#endif /* _ASM_SYSCALL_H */
Index: quilt-2.6/arch/s390/include/asm/thread_info.h
===================================================================
--- quilt-2.6.orig/arch/s390/include/asm/thread_info.h
+++ quilt-2.6/arch/s390/include/asm/thread_info.h
@@ -86,6 +86,7 @@ static inline struct thread_info *curren
* thread information flags bit numbers
*/
#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
+#define TIF_NOTIFY_RESUME 1 /* callback before returning to user */
#define TIF_SIGPENDING 2 /* signal pending */
#define TIF_NEED_RESCHED 3 /* rescheduling necessary */
#define TIF_RESTART_SVC 4 /* restart svc with new svc number */
@@ -100,6 +101,7 @@ static inline struct thread_info *curren
#define TIF_RESTORE_SIGMASK 20 /* restore signal mask in do_signal() */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
+#define _TIF_NOTIFY_RESUME (1<<TIF_NOTIFY_RESUME)
#define _TIF_RESTORE_SIGMASK (1<<TIF_RESTORE_SIGMASK)
#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
Index: quilt-2.6/arch/s390/Kconfig
===================================================================
--- quilt-2.6.orig/arch/s390/Kconfig
+++ quilt-2.6/arch/s390/Kconfig
@@ -74,6 +74,7 @@ config S390
select HAVE_KPROBES
select HAVE_KRETPROBES
select HAVE_KVM if 64BIT
+ select HAVE_ARCH_TRACEHOOK

source "init/Kconfig"

Index: quilt-2.6/arch/s390/kernel/entry64.S
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/entry64.S
+++ quilt-2.6/arch/s390/kernel/entry64.S
@@ -52,9 +52,9 @@ SP_SIZE = STACK_FRAME_OVERHEAD + __
STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
STACK_SIZE = 1 << STACK_SHIFT

-_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
_TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
-_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
_TIF_MCCK_PENDING)

#define BASED(name) name-system_call(%r13)
@@ -310,6 +310,8 @@ sysc_work:
jo sysc_reschedule
tm __TI_flags+7(%r9),_TIF_SIGPENDING
jnz sysc_sigpending
+ tm __TI_flags+7(%r9),_TIF_NOTIFY_RESUME
+ jnz sysc_notify_resume
tm __TI_flags+7(%r9),_TIF_RESTART_SVC
jo sysc_restart
tm __TI_flags+7(%r9),_TIF_SINGLE_STEP
@@ -345,6 +347,14 @@ sysc_sigpending:
j sysc_work_loop

#
+# _TIF_NOTIFY_RESUME is set, call do_notify_resume
+#
+sysc_notify_resume:
+ la %r2,SP_PTREGS(%r15) # load pt_regs
+ larl %r14,sysc_work_loop
+ jg do_notify_resume # call do_notify_resume
+
+#
# _TIF_RESTART_SVC is set, set up registers and restart svc
#
sysc_restart:
@@ -367,20 +377,19 @@ sysc_singlestep:
jg do_single_step # branch to do_sigtrap

#
-# call syscall_trace before and after system call
-# special linkage: %r12 contains the return address for trace_svc
+# call tracehook_report_syscall_entry/tracehook_report_syscall_exit before
+# and after the system call
#
sysc_tracesys:
la %r2,SP_PTREGS(%r15) # load pt_regs
la %r3,0
srl %r7,2
stg %r7,SP_R2(%r15)
- brasl %r14,syscall_trace
+ brasl %r14,do_syscall_trace_enter
lghi %r0,NR_syscalls
- clg %r0,SP_R2(%r15)
+ clgr %r0,%r2
jnh sysc_tracenogo
- lg %r7,SP_R2(%r15) # strace might have changed the
- sll %r7,2 # system call
+ slag %r7,%r2,2 # *4
lgf %r8,0(%r7,%r10)
sysc_tracego:
lmg %r3,%r6,SP_R3(%r15)
@@ -391,9 +400,8 @@ sysc_tracenogo:
tm __TI_flags+7(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
jz sysc_return
la %r2,SP_PTREGS(%r15) # load pt_regs
- la %r3,1
larl %r14,sysc_return # return point is sysc_return
- jg syscall_trace
+ jg do_syscall_trace_exit

#
# a new process exits the kernel with ret_from_fork
@@ -672,6 +680,8 @@ io_work_loop:
jo io_reschedule
tm __TI_flags+7(%r9),_TIF_SIGPENDING
jnz io_sigpending
+ tm __TI_flags+7(%r9),_TIF_NOTIFY_RESUME
+ jnz io_notify_resume
j io_restore
io_work_done:

@@ -712,6 +722,18 @@ io_sigpending:
TRACE_IRQS_OFF
j io_work_loop

+#
+# _TIF_NOTIFY_RESUME or is set, call do_notify_resume
+#
+io_notify_resume:
+ TRACE_IRQS_ON
+ stosm __SF_EMPTY(%r15),0x03 # reenable interrupts
+ la %r2,SP_PTREGS(%r15) # load pt_regs
+ brasl %r14,do_notify_resume # call do_notify_resume
+ stnsm __SF_EMPTY(%r15),0xfc # disable I/O and ext. interrupts
+ TRACE_IRQS_OFF
+ j io_work_loop
+
/*
* External interrupt handler routine
*/
Index: quilt-2.6/arch/s390/kernel/entry.S
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/entry.S
+++ quilt-2.6/arch/s390/kernel/entry.S
@@ -49,9 +49,9 @@ SP_ILC = STACK_FRAME_OVERHEAD + __P
SP_TRAP = STACK_FRAME_OVERHEAD + __PT_TRAP
SP_SIZE = STACK_FRAME_OVERHEAD + __PT_SIZE

-_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
_TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
-_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
_TIF_MCCK_PENDING)

STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
@@ -318,6 +318,8 @@ sysc_work:
bo BASED(sysc_reschedule)
tm __TI_flags+3(%r9),_TIF_SIGPENDING
bnz BASED(sysc_sigpending)
+ tm __TI_flags+3(%r9),_TIF_NOTIFY_RESUME
+ bnz BASED(sysc_notify_resume)
tm __TI_flags+3(%r9),_TIF_RESTART_SVC
bo BASED(sysc_restart)
tm __TI_flags+3(%r9),_TIF_SINGLE_STEP
@@ -356,6 +358,16 @@ sysc_sigpending:
b BASED(sysc_work_loop)

#
+# _TIF_NOTIFY_RESUME is set, call do_notify_resume
+#
+sysc_notify_resume:
+ la %r2,SP_PTREGS(%r15) # load pt_regs
+ l %r1,BASED(.Ldo_notify_resume)
+ la %r14,BASED(sysc_work_loop)
+ br %r1 # call do_notify_resume
+
+
+#
# _TIF_RESTART_SVC is set, set up registers and restart svc
#
sysc_restart:
@@ -378,20 +390,21 @@ sysc_singlestep:
br %r1 # branch to do_single_step

#
-# call trace before and after sys_call
+# call tracehook_report_syscall_entry/tracehook_report_syscall_exit before
+# and after the system call
#
sysc_tracesys:
- l %r1,BASED(.Ltrace)
+ l %r1,BASED(.Ltrace_entry)
la %r2,SP_PTREGS(%r15) # load pt_regs
la %r3,0
srl %r7,2
st %r7,SP_R2(%r15)
basr %r14,%r1
- clc SP_R2(4,%r15),BASED(.Lnr_syscalls)
+ cl %r2,BASED(.Lnr_syscalls)
bnl BASED(sysc_tracenogo)
l %r8,BASED(.Lsysc_table)
- l %r7,SP_R2(%r15) # strace might have changed the
- sll %r7,2 # system call
+ lr %r7,%r2
+ sll %r7,2 # *4
l %r8,0(%r7,%r8)
sysc_tracego:
lm %r3,%r6,SP_R3(%r15)
@@ -401,9 +414,8 @@ sysc_tracego:
sysc_tracenogo:
tm __TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
bz BASED(sysc_return)
- l %r1,BASED(.Ltrace)
+ l %r1,BASED(.Ltrace_exit)
la %r2,SP_PTREGS(%r15) # load pt_regs
- la %r3,1
la %r14,BASED(sysc_return)
br %r1

@@ -666,6 +678,8 @@ io_work_loop:
bo BASED(io_reschedule)
tm __TI_flags+3(%r9),_TIF_SIGPENDING
bnz BASED(io_sigpending)
+ tm __TI_flags+3(%r9),_TIF_NOTIFY_RESUME
+ bnz BASED(io_notify_resume)
b BASED(io_restore)
io_work_done:

@@ -704,6 +718,19 @@ io_sigpending:
TRACE_IRQS_OFF
b BASED(io_work_loop)

+#
+# _TIF_SIGPENDING is set, call do_signal
+#
+io_notify_resume:
+ TRACE_IRQS_ON
+ stosm __SF_EMPTY(%r15),0x03 # reenable interrupts
+ la %r2,SP_PTREGS(%r15) # load pt_regs
+ l %r1,BASED(.Ldo_notify_resume)
+ basr %r14,%r1 # call do_signal
+ stnsm __SF_EMPTY(%r15),0xfc # disable I/O and ext. interrupts
+ TRACE_IRQS_OFF
+ b BASED(io_work_loop)
+
/*
* External interrupt handler routine
*/
@@ -1070,6 +1097,8 @@ cleanup_io_leave_insn:
.Ldo_IRQ: .long do_IRQ
.Ldo_extint: .long do_extint
.Ldo_signal: .long do_signal
+.Ldo_notify_resume:
+ .long do_notify_resume
.Lhandle_per: .long do_single_step
.Ldo_execve: .long do_execve
.Lexecve_tail: .long execve_tail
@@ -1079,7 +1108,8 @@ cleanup_io_leave_insn:
.Lpreempt_schedule_irq:
.long preempt_schedule_irq
#endif
-.Ltrace: .long syscall_trace
+.Ltrace_entry: .long do_syscall_trace_enter
+.Ltrace_exit: .long do_syscall_trace_exit
.Lschedtail: .long schedule_tail
.Lsysc_table: .long sys_call_table
#ifdef CONFIG_TRACE_IRQFLAGS
Index: quilt-2.6/arch/s390/kernel/ptrace.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/ptrace.c
+++ quilt-2.6/arch/s390/kernel/ptrace.c
@@ -35,6 +35,7 @@
#include <linux/signal.h>
#include <linux/elf.h>
#include <linux/regset.h>
+#include <linux/tracehook.h>

#include <asm/segment.h>
#include <asm/page.h>
@@ -639,40 +640,44 @@ long compat_arch_ptrace(struct task_stru
}
#endif

-asmlinkage void
-syscall_trace(struct pt_regs *regs, int entryexit)
+asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
- if (unlikely(current->audit_context) && entryexit)
- audit_syscall_exit(AUDITSC_RESULT(regs->gprs[2]), regs->gprs[2]);
-
- if (!test_thread_flag(TIF_SYSCALL_TRACE))
- goto out;
- if (!(current->ptrace & PT_PTRACED))
- goto out;
- ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
- ? 0x80 : 0));
+ long ret;

/*
- * If the debuffer has set an invalid system call number,
- * we prepare to skip the system call restart handling.
+ * The sysc_tracesys code in entry.S stored the system
+ * call number to gprs[2].
*/
- if (!entryexit && regs->gprs[2] >= NR_syscalls)
+ ret = regs->gprs[2];
+ if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+ (tracehook_report_syscall_entry(regs) ||
+ regs->gprs[2] >= NR_syscalls)) {
+ /*
+ * Tracing decided this syscall should not happen or the
+ * debugger stored an invalid system call number. Skip
+ * the system call and the system call restart handling.
+ */
regs->trap = -1;
+ ret = -1;
+ }

- /*
- * this isn't the same as continuing with a signal, but it will do
- * for normal use. strace only continues with a signal if the
- * stopping signal is not SIGTRAP. -brl
- */
- if (current->exit_code) {
- send_sig(current->exit_code, current, 1);
- current->exit_code = 0;
- }
- out:
- if (unlikely(current->audit_context) && !entryexit)
- audit_syscall_entry(test_thread_flag(TIF_31BIT)?AUDIT_ARCH_S390:AUDIT_ARCH_S390X,
- regs->gprs[2], regs->orig_gpr2, regs->gprs[3],
- regs->gprs[4], regs->gprs[5]);
+ if (unlikely(current->audit_context))
+ audit_syscall_entry(test_thread_flag(TIF_31BIT) ?
+ AUDIT_ARCH_S390 : AUDIT_ARCH_S390X,
+ regs->gprs[2], regs->orig_gpr2,
+ regs->gprs[3], regs->gprs[4],
+ regs->gprs[5]);
+ return ret;
+}
+
+asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)
+{
+ if (unlikely(current->audit_context))
+ audit_syscall_exit(AUDITSC_RESULT(regs->gprs[2]),
+ regs->gprs[2]);
+
+ if (test_thread_flag(TIF_SYSCALL_TRACE))
+ tracehook_report_syscall_exit(regs, 0);
}

/*
Index: quilt-2.6/arch/s390/kernel/signal.c
===================================================================
--- quilt-2.6.orig/arch/s390/kernel/signal.c
+++ quilt-2.6/arch/s390/kernel/signal.c
@@ -24,6 +24,7 @@
#include <linux/tty.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
+#include <linux/tracehook.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/lowcore.h>
@@ -507,6 +508,12 @@ void do_signal(struct pt_regs *regs)
*/
if (current->thread.per_info.single_step)
set_thread_flag(TIF_SINGLE_STEP);
+
+ /*
+ * Let tracing know that we've done the handler setup.
+ */
+ tracehook_signal_handler(signr, &info, &ka, regs,
+ test_thread_flag(TIF_SINGLE_STEP));
}
return;
}
@@ -526,3 +533,9 @@ void do_signal(struct pt_regs *regs)
set_thread_flag(TIF_RESTART_SVC);
}
}
+
+void do_notify_resume(struct pt_regs *regs)
+{
+ clear_thread_flag(TIF_NOTIFY_RESUME);
+ tracehook_notify_resume(regs);
+}

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.

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Next message: Martin Schwidefsky: "[patch 16/21] dcssblk: add >2G DCSSs support and stacked contiguous DCSSs support."
Previous message: Martin Schwidefsky: "[patch 18/21] Move private simple udelay function to arch/s390/lib/delay.c."
In reply to: Martin Schwidefsky: "[patch 18/21] Move private simple udelay function to arch/s390/lib/delay.c."
Next in thread: Martin Schwidefsky: "[patch 16/21] dcssblk: add >2G DCSSs support and stacked contiguous DCSSs support."
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