microblaze: Support ptrace syscall tracing.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

2 files changed, 122 insertions, 12 deletions

diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
index c7353e79f4a2..acc1f05d1e2c 100644
--- a/arch/microblaze/kernel/entry.S
+++ b/arch/microblaze/kernel/entry.S
@@ -308,38 +308,69 @@ C_ENTRY(_user_exception):
         swi     r12, r1, PTO+PT_R0;
         tovirt(r1,r1)
 
-        la      r15, r0, ret_from_trap-8
 /* where the trap should return need -8 to adjust for rtsd r15, 8*/
 /* Jump to the appropriate function for the system call number in r12
  * (r12 is not preserved), or return an error if r12 is not valid. The LP
  * register should point to the location where
  * the called function should return.  [note that MAKE_SYS_CALL uses label 1] */
-        /* See if the system call number is valid.  */
+
+        # Step into virtual mode.
+        set_vms;
+        addik   r11, r0, 3f
+        rtid    r11, 0
+        nop
+3:
+        add     r11, r0, CURRENT_TASK    /* Get current task ptr into r11 */
+        lwi     r11, r11, TS_THREAD_INFO /* get thread info */
+        lwi     r11, r11, TI_FLAGS       /* get flags in thread info */
+        andi    r11, r11, _TIF_WORK_SYSCALL_MASK
+        beqi    r11, 4f
+
+        addik   r3, r0, -ENOSYS
+        swi     r3, r1, PTO + PT_R3
+        brlid   r15, do_syscall_trace_enter
+        addik   r5, r1, PTO + PT_R0
+
+        # do_syscall_trace_enter returns the new syscall nr.
+        addk    r12, r0, r3
+        lwi     r5, r1, PTO+PT_R5;
+        lwi     r6, r1, PTO+PT_R6;
+        lwi     r7, r1, PTO+PT_R7;
+        lwi     r8, r1, PTO+PT_R8;
+        lwi     r9, r1, PTO+PT_R9;
+        lwi     r10, r1, PTO+PT_R10;
+4:
+/* Jump to the appropriate function for the system call number in r12
+ * (r12 is not preserved), or return an error if r12 is not valid.
+ * The LP register should point to the location where the called function
+ * should return.  [note that MAKE_SYS_CALL uses label 1] */
+        /* See if the system call number is valid */
         addi    r11, r12, -__NR_syscalls;
-        bgei    r11,1f;
+        bgei    r11,5f;
         /* Figure out which function to use for this system call.  */
         /* Note Microblaze barrel shift is optional, so don't rely on it */
         add     r12, r12, r12;                  /* convert num -> ptr */
         add     r12, r12, r12;
 
         /* Trac syscalls and stored them to r0_ram */
-        lwi     r3, r12, 0x400 + TOPHYS(r0_ram)
+        lwi     r3, r12, 0x400 + r0_ram
         addi    r3, r3, 1
-        swi     r3, r12, 0x400 + TOPHYS(r0_ram)
+        swi     r3, r12, 0x400 + r0_ram
+
+        # Find and jump into the syscall handler.
+        lwi     r12, r12, sys_call_table
+        /* where the trap should return need -8 to adjust for rtsd r15, 8 */
+        la      r15, r0, ret_from_trap-8
+        bra     r12
 
-        lwi     r12, r12, TOPHYS(sys_call_table); /* Function ptr */
-        /* Make the system call.  to r12*/
-        set_vms;
-        rtid    r12, 0;
-        nop;
         /* The syscall number is invalid, return an error.  */
-1:      VM_ON;  /* RETURN() expects virtual mode*/
+5:
         addi    r3, r0, -ENOSYS;
         rtsd    r15,8;          /* looks like a normal subroutine return */
         or      r0, r0, r0
 
 
-/* Entry point used to return from a syscall/trap.  */
+/* Entry point used to return from a syscall/trap */
 /* We re-enable BIP bit before state restore */
 C_ENTRY(ret_from_trap):
         set_bip;                        /*  Ints masked for state restore*/
@@ -349,6 +380,23 @@ C_ENTRY(ret_from_trap):
 
         /* We're returning to user mode, so check for various conditions that
          * trigger rescheduling. */
+        # FIXME: Restructure all these flag checks.
+        add     r11, r0, CURRENT_TASK;  /* Get current task ptr into r11 */
+        lwi     r11, r11, TS_THREAD_INFO;       /* get thread info */
+        lwi     r11, r11, TI_FLAGS;             /* get flags in thread info */
+        andi    r11, r11, _TIF_WORK_SYSCALL_MASK
+        beqi    r11, 1f
+
+        swi     r3, r1, PTO + PT_R3
+        swi     r4, r1, PTO + PT_R4
+        brlid   r15, do_syscall_trace_leave
+        addik   r5, r1, PTO + PT_R0
+        lwi     r3, r1, PTO + PT_R3
+        lwi     r4, r1, PTO + PT_R4
+1:
+
+        /* We're returning to user mode, so check for various conditions that
+         * trigger rescheduling. */
         /* Get current task ptr into r11 */
         add     r11, r0, CURRENT_TASK;  /* Get current task ptr into r11 */
         lwi     r11, r11, TS_THREAD_INFO;       /* get thread info */
diff --git a/arch/microblaze/kernel/ptrace.c b/arch/microblaze/kernel/ptrace.c
index 53ff39af6a5c..4b3ac32754de 100644
--- a/arch/microblaze/kernel/ptrace.c
+++ b/arch/microblaze/kernel/ptrace.c
@@ -29,6 +29,10 @@
 #include <linux/sched.h>
 #include <linux/ptrace.h>
 #include <linux/signal.h>
+#include <linux/elf.h>
+#include <linux/audit.h>
+#include <linux/seccomp.h>
+#include <linux/tracehook.h>
 
 #include <linux/errno.h>
 #include <asm/processor.h>
@@ -174,6 +178,64 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
         return rval;
 }
 
+asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
+{
+        long ret = 0;
+
+        secure_computing(regs->r12);
+
+        if (test_thread_flag(TIF_SYSCALL_TRACE) &&
+            tracehook_report_syscall_entry(regs))
+                /*
+                 * Tracing decided this syscall should not happen.
+                 * We'll return a bogus call number to get an ENOSYS
+                 * error, but leave the original number in regs->regs[0].
+                 */
+                ret = -1L;
+
+        if (unlikely(current->audit_context))
+                audit_syscall_entry(EM_XILINX_MICROBLAZE, regs->r12,
+                                    regs->r5, regs->r6,
+                                    regs->r7, regs->r8);
+
+        return ret ?: regs->r12;
+}
+
+asmlinkage void do_syscall_trace_leave(struct pt_regs *regs)
+{
+        int step;
+
+        if (unlikely(current->audit_context))
+                audit_syscall_exit(AUDITSC_RESULT(regs->r3), regs->r3);
+
+        step = test_thread_flag(TIF_SINGLESTEP);
+        if (step || test_thread_flag(TIF_SYSCALL_TRACE))
+                tracehook_report_syscall_exit(regs, step);
+}
+
+#if 0
+static asmlinkage void syscall_trace(void)
+{
+        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 */
+        ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
+                                ? 0x80 : 0));
+        /*
+         * 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;
+        }
+}
+#endif
+
 void ptrace_disable(struct task_struct *child)
 {
         /* nothing to do */