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Subject[PATCH] UML utrace support, step 1
Below is the first step in your Fix-Your-Broken-Arch-HOWTO for UML.

Do you want incremental patches as I go along, or replacement ones?

BTW, UML runs on the utrace in -mm (i.e. utrace on the host), which it
didn't with several Fedora kernels.

Jeff

--
Work email - jdike at linux dot intel dot com



The first step in making the utrace arch changes for UML. It builds
and runs now, but ptrace is broken.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
--
arch/um/kernel/exec.c | 1
arch/um/kernel/process.c | 6
arch/um/kernel/ptrace.c | 333 +++++-----------------------------------
arch/um/kernel/signal.c | 5
arch/um/kernel/skas/syscall.c | 4
arch/um/sys-i386/signal.c | 4
include/asm-um/ptrace-generic.h | 3
include/asm-um/tracehook.h | 66 +++++++
8 files changed, 115 insertions(+), 307 deletions(-)
Index: linux-2.6.18-mm/arch/um/kernel/exec.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/kernel/exec.c 2007-02-20 16:18:07.000000000 -0500
+++ linux-2.6.18-mm/arch/um/kernel/exec.c 2007-02-20 16:18:50.000000000 -0500
@@ -51,7 +51,6 @@ static long execve1(char *file, char __u
error = do_execve(file, argv, env, &current->thread.regs);
if (error == 0){
task_lock(current);
- current->ptrace &= ~PT_DTRACE;
#ifdef SUBARCH_EXECVE1
SUBARCH_EXECVE1(&current->thread.regs.regs);
#endif
Index: linux-2.6.18-mm/arch/um/kernel/process.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/kernel/process.c 2007-02-20 16:18:07.000000000 -0500
+++ linux-2.6.18-mm/arch/um/kernel/process.c 2007-02-20 16:18:50.000000000 -0500
@@ -458,11 +458,11 @@ int singlestepping(void * t)
{
struct task_struct *task = t ? t : current;

- if ( ! (task->ptrace & PT_DTRACE) )
- return(0);
+ if (!test_thread_flag(TIF_SINGLESTEP))
+ return 0;

if (task->thread.singlestep_syscall)
- return(1);
+ return 1;

return 2;
}
Index: linux-2.6.18-mm/arch/um/kernel/ptrace.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/kernel/ptrace.c 2007-02-20 16:18:07.000000000 -0500
+++ linux-2.6.18-mm/arch/um/kernel/ptrace.c 2007-02-20 16:18:50.000000000 -0500
@@ -3,261 +3,29 @@
* Licensed under the GPL
*/

-#include "linux/sched.h"
-#include "linux/mm.h"
-#include "linux/errno.h"
-#include "linux/smp_lock.h"
-#include "linux/security.h"
-#include "linux/ptrace.h"
-#include "linux/audit.h"
-#ifdef CONFIG_PROC_MM
-#include "linux/proc_mm.h"
-#endif
-#include "asm/ptrace.h"
-#include "asm/uaccess.h"
-#include "kern_util.h"
-#include "skas_ptrace.h"
-#include "sysdep/ptrace.h"
-#include "os.h"
-
-static inline void set_singlestepping(struct task_struct *child, int on)
+#include <linux/audit.h>
+#include <linux/elf.h>
+#include <linux/module.h>
+#include <linux/ptrace.h>
+#include <linux/tracehook.h>
+
+const struct utrace_regset_view utrace_um_native = {
+ .name = "um",
+ .e_machine = ELF_ARCH,
+ .regsets = NULL,
+ .n = 0,
+};
+EXPORT_SYMBOL_GPL(utrace_um_native);
+
+int arch_ptrace(long *req, struct task_struct *child,
+ struct utrace_attached_engine *engine,
+ unsigned long addr, unsigned long data, long *val)
{
- if (on)
- child->ptrace |= PT_DTRACE;
- else
- child->ptrace &= ~PT_DTRACE;
- child->thread.singlestep_syscall = 0;
-
-#ifdef SUBARCH_SET_SINGLESTEPPING
- SUBARCH_SET_SINGLESTEPPING(child, on);
-#endif
+ return -ENOSYS;
}

-/*
- * Called by kernel/ptrace.c when detaching..
- */
-void ptrace_disable(struct task_struct *child)
-{
- set_singlestepping(child,0);
-}
-
-extern int peek_user(struct task_struct * child, long addr, long data);
-extern int poke_user(struct task_struct * child, long addr, long data);
-
-long arch_ptrace(struct task_struct *child, long request, long addr, long data)
-{
- int i, ret;
- unsigned long __user *p = (void __user *)(unsigned long)data;
-
- switch (request) {
- /* when I and D space are separate, these will need to be fixed. */
- case PTRACE_PEEKTEXT: /* read word at location addr. */
- case PTRACE_PEEKDATA: {
- unsigned long tmp;
- int copied;
-
- ret = -EIO;
- copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0);
- if (copied != sizeof(tmp))
- break;
- ret = put_user(tmp, p);
- break;
- }
-
- /* read the word at location addr in the USER area. */
- case PTRACE_PEEKUSR:
- ret = peek_user(child, addr, data);
- break;
-
- /* when I and D space are separate, this will have to be fixed. */
- case PTRACE_POKETEXT: /* write the word at location addr. */
- case PTRACE_POKEDATA:
- ret = -EIO;
- if (access_process_vm(child, addr, &data, sizeof(data),
- 1) != sizeof(data))
- break;
- ret = 0;
- break;
-
- case PTRACE_POKEUSR: /* write the word at location addr in the USER area */
- ret = poke_user(child, addr, data);
- break;
-
- case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */
- case PTRACE_CONT: { /* restart after signal. */
- ret = -EIO;
- if (!valid_signal(data))
- break;
-
- set_singlestepping(child, 0);
- if (request == PTRACE_SYSCALL) {
- set_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
- }
- else {
- clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
- }
- child->exit_code = data;
- wake_up_process(child);
- ret = 0;
- break;
- }
-
-/*
- * make the child exit. Best I can do is send it a sigkill.
- * perhaps it should be put in the status that it wants to
- * exit.
- */
- case PTRACE_KILL: {
- ret = 0;
- if (child->exit_state == EXIT_ZOMBIE) /* already dead */
- break;
-
- set_singlestepping(child, 0);
- child->exit_code = SIGKILL;
- wake_up_process(child);
- break;
- }
-
- case PTRACE_SINGLESTEP: { /* set the trap flag. */
- ret = -EIO;
- if (!valid_signal(data))
- break;
- clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
- set_singlestepping(child, 1);
- child->exit_code = data;
- /* give it a chance to run. */
- wake_up_process(child);
- ret = 0;
- break;
- }
-
- case PTRACE_DETACH:
- /* detach a process that was attached. */
- ret = ptrace_detach(child, data);
- break;
-
-#ifdef PTRACE_GETREGS
- case PTRACE_GETREGS: { /* Get all gp regs from the child. */
- if (!access_ok(VERIFY_WRITE, p, MAX_REG_OFFSET)) {
- ret = -EIO;
- break;
- }
- for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
- __put_user(getreg(child, i), p);
- p++;
- }
- ret = 0;
- break;
- }
-#endif
-#ifdef PTRACE_SETREGS
- case PTRACE_SETREGS: { /* Set all gp regs in the child. */
- unsigned long tmp = 0;
- if (!access_ok(VERIFY_READ, p, MAX_REG_OFFSET)) {
- ret = -EIO;
- break;
- }
- for ( i = 0; i < MAX_REG_OFFSET; i += sizeof(long) ) {
- __get_user(tmp, p);
- putreg(child, i, tmp);
- p++;
- }
- ret = 0;
- break;
- }
-#endif
-#ifdef PTRACE_GETFPREGS
- case PTRACE_GETFPREGS: /* Get the child FPU state. */
- ret = get_fpregs(data, child);
- break;
-#endif
-#ifdef PTRACE_SETFPREGS
- case PTRACE_SETFPREGS: /* Set the child FPU state. */
- ret = set_fpregs(data, child);
- break;
-#endif
-#ifdef PTRACE_GETFPXREGS
- case PTRACE_GETFPXREGS: /* Get the child FPU state. */
- ret = get_fpxregs(data, child);
- break;
-#endif
-#ifdef PTRACE_SETFPXREGS
- case PTRACE_SETFPXREGS: /* Set the child FPU state. */
- ret = set_fpxregs(data, child);
- break;
-#endif
- case PTRACE_GET_THREAD_AREA:
- ret = ptrace_get_thread_area(child, addr,
- (struct user_desc __user *) data);
- break;
-
- case PTRACE_SET_THREAD_AREA:
- ret = ptrace_set_thread_area(child, addr,
- (struct user_desc __user *) data);
- break;
-
- case PTRACE_FAULTINFO: {
- /* Take the info from thread->arch->faultinfo,
- * but transfer max. sizeof(struct ptrace_faultinfo).
- * On i386, ptrace_faultinfo is smaller!
- */
- ret = copy_to_user(p, &child->thread.arch.faultinfo,
- sizeof(struct ptrace_faultinfo));
- if(ret)
- break;
- break;
- }
-
-#ifdef PTRACE_LDT
- case PTRACE_LDT: {
- struct ptrace_ldt ldt;
-
- if(copy_from_user(&ldt, p, sizeof(ldt))){
- ret = -EIO;
- break;
- }
-
- /* This one is confusing, so just punt and return -EIO for
- * now
- */
- ret = -EIO;
- break;
- }
-#endif
-#ifdef CONFIG_PROC_MM
- case PTRACE_SWITCH_MM: {
- struct mm_struct *old = child->mm;
- struct mm_struct *new = proc_mm_get_mm(data);
-
- if(IS_ERR(new)){
- ret = PTR_ERR(new);
- break;
- }
-
- atomic_inc(&new->mm_users);
- child->mm = new;
- child->active_mm = new;
- mmput(old);
- ret = 0;
- break;
- }
-#endif
-#ifdef PTRACE_ARCH_PRCTL
- case PTRACE_ARCH_PRCTL:
- /* XXX Calls ptrace on the host - needs some SMP thinking */
- ret = arch_prctl_skas(child, data, (void *) addr);
- break;
-#endif
- default:
- ret = ptrace_request(child, request, addr, data);
- break;
- }
-
- return ret;
-}
-
-void send_sigtrap(struct task_struct *tsk, union uml_pt_regs *regs,
- int error_code)
+static void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
+ int error_code)
{
struct siginfo info;

@@ -266,56 +34,39 @@ void send_sigtrap(struct task_struct *ts
info.si_code = TRAP_BRKPT;

/* User-mode eip? */
- info.si_addr = UPT_IS_USER(regs) ? (void __user *) UPT_IP(regs) : NULL;
+ info.si_addr = UPT_IS_USER(&regs->regs) ?
+ (void __user *) UPT_IP(&regs->regs) : NULL;

/* Send us the fakey SIGTRAP */
force_sig_info(SIGTRAP, &info, tsk);
}

-/* XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
- * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
+/* notification of system call entry/exit
+ * - triggered by current->work.syscall_trace
*/
-void syscall_trace(union uml_pt_regs *regs, int entryexit)
+void do_syscall_trace(struct pt_regs *regs, int entryexit)
{
- int is_singlestep = (current->ptrace & PT_DTRACE) && entryexit;
- int tracesysgood;
+ /* do the secure computing check first */
+ if (!entryexit)
+ secure_computing(PT_REGS_SYSCALL_NR(regs));
+
+ if (unlikely(current->audit_context) && entryexit)
+ audit_syscall_exit(AUDITSC_RESULT(UPT_SYSCALL_RET(regs)),
+ UPT_SYSCALL_RET(regs));
+
+ if (test_thread_flag(TIF_SYSCALL_TRACE))
+ tracehook_report_syscall(regs, entryexit);
+
+ if (test_thread_flag(TIF_SINGLESTEP) && entryexit) {
+ send_sigtrap(current, regs, 0); /* XXX */
+ tracehook_report_syscall_step(regs);
+ }

- if (unlikely(current->audit_context)) {
- if (!entryexit)
- audit_syscall_entry(HOST_AUDIT_ARCH,
+ if (unlikely(current->audit_context) && !entryexit)
+ audit_syscall_entry(HOST_AUDIT_ARCH,
UPT_SYSCALL_NR(regs),
UPT_SYSCALL_ARG1(regs),
UPT_SYSCALL_ARG2(regs),
UPT_SYSCALL_ARG3(regs),
UPT_SYSCALL_ARG4(regs));
- else audit_syscall_exit(AUDITSC_RESULT(UPT_SYSCALL_RET(regs)),
- UPT_SYSCALL_RET(regs));
- }
-
- /* Fake a debug trap */
- if (is_singlestep)
- send_sigtrap(current, regs, 0);
-
- if (!test_thread_flag(TIF_SYSCALL_TRACE))
- return;
-
- if (!(current->ptrace & PT_PTRACED))
- return;
-
- /* the 0x80 provides a way for the tracing parent to distinguish
- between a syscall stop and SIGTRAP delivery */
- tracesysgood = (current->ptrace & PT_TRACESYSGOOD);
- ptrace_notify(SIGTRAP | (tracesysgood ? 0x80 : 0));
-
- if (entryexit) /* force do_signal() --> is_syscall() */
- set_thread_flag(TIF_SIGPENDING);
-
- /* 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;
- }
}
Index: linux-2.6.18-mm/include/asm-um/tracehook.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.18-mm/include/asm-um/tracehook.h 2007-02-20 16:18:50.000000000 -0500
@@ -0,0 +1,66 @@
+/*
+ * Tracing hooks, i386 CPU support
+ *
+ * Copyright (C) 2006, 2007 Red Hat, Inc. All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License v.2.
+ *
+ * Red Hat Author: Roland McGrath.
+ *
+ * Munged for UML - jdike@{addtoit,linux.intel}.com
+ */
+
+#ifndef _ASM_TRACEHOOK_H
+#define _ASM_TRACEHOOK_H 1
+
+#include <linux/sched.h>
+#include <asm/ptrace.h>
+#include <asm/thread_info.h>
+
+/*
+ * See linux/tracehook.h for the descriptions of what these need to do.
+ */
+
+#define ARCH_HAS_SINGLE_STEP (1)
+
+static inline void tracehook_enable_single_step(struct task_struct *tsk)
+{
+ set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
+}
+
+static inline void tracehook_disable_single_step(struct task_struct *tsk)
+{
+ clear_tsk_thread_flag(tsk, TIF_SINGLESTEP);
+}
+
+static inline int tracehook_single_step_enabled(struct task_struct *tsk)
+{
+ return test_tsk_thread_flag(tsk, TIF_SINGLESTEP);
+}
+
+static inline void tracehook_enable_syscall_trace(struct task_struct *tsk)
+{
+ set_tsk_thread_flag(tsk, TIF_SYSCALL_TRACE);
+}
+
+static inline void tracehook_disable_syscall_trace(struct task_struct *tsk)
+{
+ clear_tsk_thread_flag(tsk, TIF_SYSCALL_TRACE);
+}
+
+static inline void tracehook_abort_syscall(struct pt_regs *regs)
+{
+ PT_REGS_SYSCALL_NR(regs) = -1;
+}
+
+extern const struct utrace_regset_view utrace_um_native;
+static inline const struct utrace_regset_view *
+utrace_native_view(struct task_struct *tsk)
+{
+ return &utrace_um_native;
+}
+
+
+#endif
Index: linux-2.6.18-mm/arch/um/kernel/signal.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/kernel/signal.c 2007-02-20 16:18:37.000000000 -0500
+++ linux-2.6.18-mm/arch/um/kernel/signal.c 2007-02-20 16:18:50.000000000 -0500
@@ -14,6 +14,7 @@
#include "linux/tty.h"
#include "linux/binfmts.h"
#include "linux/ptrace.h"
+#include "linux/tracehook.h"
#include "asm/signal.h"
#include "asm/uaccess.h"
#include "asm/unistd.h"
@@ -93,6 +94,8 @@ static int handle_signal(struct pt_regs
sigaddset(&current->blocked, signr);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
+
+ tracehook_report_handle_signal(signr, ka, oldset, regs);
}

return err;
@@ -148,7 +151,7 @@ static int kern_do_signal(struct pt_regs
* on the host. The tracing thread will check this flag and
* PTRACE_SYSCALL if necessary.
*/
- if(current->ptrace & PT_DTRACE)
+ if(test_thread_flag(TIF_SYSCALL_TRACE))
current->thread.singlestep_syscall =
is_syscall(PT_REGS_IP(&current->thread.regs));

Index: linux-2.6.18-mm/arch/um/kernel/skas/syscall.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/kernel/skas/syscall.c 2007-02-20 16:18:07.000000000 -0500
+++ linux-2.6.18-mm/arch/um/kernel/skas/syscall.c 2007-02-20 16:18:50.000000000 -0500
@@ -19,8 +19,6 @@ void handle_syscall(union uml_pt_regs *r
long result;
int syscall;

- syscall_trace(r, 0);
-
current->thread.nsyscalls++;
nsyscalls++;

@@ -38,6 +36,4 @@ void handle_syscall(union uml_pt_regs *r
else result = EXECUTE_SYSCALL(syscall, regs);

REGS_SET_SYSCALL_RETURN(r->skas.regs, result);
-
- syscall_trace(r, 1);
}
Index: linux-2.6.18-mm/arch/um/sys-i386/signal.c
===================================================================
--- linux-2.6.18-mm.orig/arch/um/sys-i386/signal.c 2007-02-20 16:18:07.000000000 -0500
+++ linux-2.6.18-mm/arch/um/sys-i386/signal.c 2007-02-20 16:18:50.000000000 -0500
@@ -267,8 +267,6 @@ int setup_signal_stack_sc(unsigned long
PT_REGS_EDX(regs) = (unsigned long) 0;
PT_REGS_ECX(regs) = (unsigned long) 0;

- if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
- ptrace_notify(SIGTRAP);
return 0;

err:
@@ -324,8 +322,6 @@ int setup_signal_stack_si(unsigned long
PT_REGS_EDX(regs) = (unsigned long) &frame->info;
PT_REGS_ECX(regs) = (unsigned long) &frame->uc;

- if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
- ptrace_notify(SIGTRAP);
return 0;

err:
Index: linux-2.6.18-mm/include/asm-um/ptrace-generic.h
===================================================================
--- linux-2.6.18-mm.orig/include/asm-um/ptrace-generic.h 2007-02-20 16:18:07.000000000 -0500
+++ linux-2.6.18-mm/include/asm-um/ptrace-generic.h 2007-02-20 16:18:50.000000000 -0500
@@ -44,9 +44,6 @@ extern int set_fpxregs(unsigned long buf

extern void show_regs(struct pt_regs *regs);

-extern void send_sigtrap(struct task_struct *tsk, union uml_pt_regs *regs,
- int error_code);
-
extern int arch_copy_tls(struct task_struct *new);
extern void clear_flushed_tls(struct task_struct *task);

-
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