microblaze: Support brki rX, 0x18 for user application debugging
This is the first patch which add support for
user application debugging through brki rX, 0x18 vector.
This patch has side effect which also remove security issue
to use brki rX, 0x18 to freeze kernel.
Support for old gdb support via priviledged exception
(brk r0, r0) is still there. It will be remove in future.
Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
index 397754c..5a5cb58 100644
--- a/arch/microblaze/kernel/entry.S
+++ b/arch/microblaze/kernel/entry.S
@@ -778,19 +778,22 @@
addik r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack. */
SAVE_REGS;
+ swi r17, r1, PTO+PT_R17;
+ swi r16, r1, PTO+PT_R16;
+ swi r16, r1, PTO+PT_PC; /* Save LP */
swi r0, r1, PTO + PT_MODE; /* Was in user-mode. */
lwi r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
swi r11, r1, PTO+PT_R1; /* Store user SP. */
-2:
+2: lwi CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
tovirt(r1,r1)
set_vms;
- addi r5, r0, SIGTRAP /* send the trap signal */
- add r6, r0, CURRENT_TASK; /* Get current task ptr into r11 */
- addk r7, r0, r0 /* 3rd param zero */
-dbtrap_call: rtbd r0, send_sig;
+ addik r5, r1, PTO;
addik r15, r0, dbtrap_call;
+dbtrap_call: /* return point for kernel/user entry */
+ rtbd r0, sw_exception
+ nop
set_bip; /* Ints masked for state restore*/
lwi r11, r1, PTO + PT_MODE;
@@ -838,6 +841,8 @@
tophys(r1,r1);
RESTORE_REGS
+ lwi r17, r1, PTO+PT_R17;
+ lwi r16, r1, PTO+PT_R16;
addik r1, r1, STATE_SAVE_SIZE /* Clean up stack space. */
@@ -854,11 +859,10 @@
tovirt(r1,r1);
6:
DBTRAP_return: /* Make global symbol for debugging */
- rtbd r14, 0; /* Instructions to return from an IRQ */
+ rtbd r16, 0; /* Instructions to return from an IRQ */
nop;
-
ENTRY(_switch_to)
/* prepare return value */
addk r3, r0, CURRENT_TASK
@@ -946,13 +950,6 @@
ENTRY(_reset)
brai 0x70; /* Jump back to FS-boot */
-ENTRY(_break)
- mfs r5, rmsr
- swi r5, r0, 0x250 + TOPHYS(r0_ram)
- mfs r5, resr
- swi r5, r0, 0x254 + TOPHYS(r0_ram)
- bri 0
-
/* These are compiled and loaded into high memory, then
* copied into place in mach_early_setup */
.section .init.ivt, "ax"
@@ -964,12 +961,9 @@
nop
brai TOPHYS(_user_exception); /* syscall handler */
brai TOPHYS(_interrupt); /* Interrupt handler */
- brai TOPHYS(_break); /* nmi trap handler */
+ brai TOPHYS(_debug_exception); /* debug trap handler */
brai TOPHYS(_hw_exception_handler); /* HW exception handler */
- .org 0x60
- brai TOPHYS(_debug_exception); /* debug trap handler*/
-
.section .rodata,"a"
#include "syscall_table.S"
diff --git a/arch/microblaze/kernel/exceptions.c b/arch/microblaze/kernel/exceptions.c
index 02cbdfe..e0c6f8c 100644
--- a/arch/microblaze/kernel/exceptions.c
+++ b/arch/microblaze/kernel/exceptions.c
@@ -48,6 +48,12 @@
do_exit(err);
}
+/* for user application debugging */
+void sw_exception(struct pt_regs *regs)
+{
+ _exception(SIGTRAP, regs, TRAP_BRKPT, regs->r16);
+}
+
void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
{
siginfo_t info;
@@ -143,7 +149,7 @@
#ifdef CONFIG_MMU
case MICROBLAZE_PRIVILEGED_EXCEPTION:
pr_debug(KERN_WARNING "Privileged exception\n");
- /* "brk r0,r0" - used as debug breakpoint */
+ /* "brk r0,r0" - used as debug breakpoint - old toolchain */
if (get_user(code, (unsigned long *)regs->pc) == 0
&& code == 0x980c0000) {
_exception(SIGTRAP, regs, TRAP_BRKPT, addr);