Commit 2d5973cb authored by Michal Simek's avatar Michal Simek

microblaze: Add KGDB support

Kgdb uses brki r16, 0x18 instruction to call
low level _debug_exception function which save
current state to pt_regs and call microblaze_kgdb_break
function. _debug_exception should be called only from
the kernel space. User space calling is not supported
because user application debugging uses different handling.

pt_regs_to_gdb_regs loads additional special registers
which can't be changed

 * Enable KGDB in Kconfig
 * Remove ancient not-tested KGDB support
 * Remove ancient _debug_exception code from entry.S

Only MMU KGDB support is supported.
Signed-off-by: default avatarMichal Simek <monstr@monstr.eu>
CC: Jason Wessel <jason.wessel@windriver.com>
CC: John Williams <john.williams@petalogix.com>
CC: Edgar E. Iglesias <edgar.iglesias@petalogix.com>
CC: linux-kernel@vger.kernel.org
Acked-by: default avatarJason Wessel <jason.wessel@windriver.com>
parent 751f1605
......@@ -14,6 +14,7 @@ config MICROBLAZE
select USB_ARCH_HAS_EHCI
select ARCH_WANT_OPTIONAL_GPIOLIB
select HAVE_OPROFILE
select HAVE_ARCH_KGDB
select HAVE_DMA_ATTRS
select HAVE_DMA_API_DEBUG
select TRACING_SUPPORT
......
......@@ -69,22 +69,6 @@ asmlinkage void full_exception(struct pt_regs *regs, unsigned int type,
void die(const char *str, struct pt_regs *fp, long err);
void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr);
#if defined(CONFIG_KGDB)
void (*debugger)(struct pt_regs *regs);
int (*debugger_bpt)(struct pt_regs *regs);
int (*debugger_sstep)(struct pt_regs *regs);
int (*debugger_iabr_match)(struct pt_regs *regs);
int (*debugger_dabr_match)(struct pt_regs *regs);
void (*debugger_fault_handler)(struct pt_regs *regs);
#else
#define debugger(regs) do { } while (0)
#define debugger_bpt(regs) 0
#define debugger_sstep(regs) 0
#define debugger_iabr_match(regs) 0
#define debugger_dabr_match(regs) 0
#define debugger_fault_handler ((void (*)(struct pt_regs *))0)
#endif
#endif /*__ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_MICROBLAZE_EXCEPTIONS_H */
#ifdef __KERNEL__
#ifndef __MICROBLAZE_KGDB_H__
#define __MICROBLAZE_KGDB_H__
#ifndef __ASSEMBLY__
#define CACHE_FLUSH_IS_SAFE 1
#define BUFMAX 2048
/*
* 32 32-bit general purpose registers (r0-r31)
* 6 32-bit special registers (pc, msr, ear, esr, fsr, btr)
* 12 32-bit PVR
* 7 32-bit MMU Regs (redr, rpid, rzpr, rtlbx, rtlbsx, rtlblo, rtlbhi)
* ------
* 57 registers
*/
#define NUMREGBYTES (57 * 4)
#define BREAK_INSTR_SIZE 4
static inline void arch_kgdb_breakpoint(void)
{
__asm__ __volatile__("brki r16, 0x18;");
}
#endif /* __ASSEMBLY__ */
#endif /* __MICROBLAZE_KGDB_H__ */
#endif /* __KERNEL__ */
......@@ -28,5 +28,6 @@ obj-$(CONFIG_MODULES) += microblaze_ksyms.o module.o
obj-$(CONFIG_MMU) += misc.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o mcount.o
obj-$(CONFIG_KGDB) += kgdb.o
obj-y += entry$(MMU).o
......@@ -745,11 +745,8 @@ IRQ_return: /* MS: Make global symbol for debugging */
nop
/*
* `Debug' trap
* We enter dbtrap in "BIP" (breakpoint) mode.
* So we exit the breakpoint mode with an 'rtbd' and proceed with the
* original dbtrap.
* however, wait to save state first
* Debug trap for KGDB. Enter to _debug_exception by brki r16, 0x18
* and call handling function with saved pt_regs
*/
C_ENTRY(_debug_exception):
/* BIP bit is set on entry, no interrupts can occur */
......@@ -759,18 +756,44 @@ C_ENTRY(_debug_exception):
nop
andi r1, r1, MSR_UMS
bnei r1, 1f
/* Kernel-mode state save. */
/* MS: Kernel-mode state save - kgdb */
lwi r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
tophys(r1,r1);
addik r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack. */
/* BIP bit is set on entry, no interrupts can occur */
addik r1, r1, CONFIG_KERNEL_BASE_ADDR - CONFIG_KERNEL_START - STATE_SAVE_SIZE;
SAVE_REGS;
/* save all regs to pt_reg structure */
swi r0, r1, PTO+PT_R0; /* R0 must be saved too */
swi r14, r1, PTO+PT_R14 /* rewrite saved R14 value */
swi r16, r1, PTO+PT_R16
swi r16, r1, PTO+PT_PC; /* PC and r16 are the same */
swi r17, r1, PTO+PT_R17
/* save special purpose registers to pt_regs */
mfs r11, rear;
swi r11, r1, PTO+PT_EAR;
mfs r11, resr;
swi r11, r1, PTO+PT_ESR;
mfs r11, rfsr;
swi r11, r1, PTO+PT_FSR;
/* stack pointer is in physical address at it is decrease
* by STATE_SAVE_SIZE but we need to get correct R1 value */
addik r11, r1, CONFIG_KERNEL_START - CONFIG_KERNEL_BASE_ADDR + STATE_SAVE_SIZE;
swi r11, r1, PTO+PT_R1
/* MS: r31 - current pointer isn't changed */
tovirt(r1,r1)
#ifdef CONFIG_KGDB
addi r5, r1, PTO /* pass pt_reg address as the first arg */
la r15, r0, dbtrap_call; /* return address */
rtbd r0, microblaze_kgdb_break
nop;
#endif
/* MS: Place handler for brki from kernel space if KGDB is OFF.
* It is very unlikely that another brki instruction is called. */
bri 0
swi r1, r1, PTO + PT_MODE;
brid 2f;
nop; /* Fill delay slot */
1: /* User-mode state save. */
lwi r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
/* MS: User-mode state save - gdb */
1: lwi r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
tophys(r1,r1);
lwi r1, r1, TS_THREAD_INFO; /* get the thread info */
addik r1, r1, THREAD_SIZE; /* calculate kernel stack pointer */
......@@ -781,36 +804,32 @@ C_ENTRY(_debug_exception):
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: lwi CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
lwi CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
tovirt(r1,r1)
set_vms;
addik r5, r1, PTO;
addik r15, r0, dbtrap_call;
dbtrap_call: /* return point for kernel/user entry */
dbtrap_call: /* Return point for kernel/user entry + 8 because of rtsd r15, 8 */
rtbd r0, sw_exception
nop
set_bip; /* Ints masked for state restore*/
/* MS: The first instruction for the second part of the gdb/kgdb */
set_bip; /* Ints masked for state restore */
lwi r11, r1, PTO + PT_MODE;
bnei r11, 2f;
/* MS: Return to user space - gdb */
/* Get current task ptr into r11 */
lwi r11, CURRENT_TASK, TS_THREAD_INFO; /* get thread info */
lwi r11, r11, TI_FLAGS; /* get flags in thread info */
andi r11, r11, _TIF_NEED_RESCHED;
beqi r11, 5f;
/* Call the scheduler before returning from a syscall/trap. */
/* Call the scheduler before returning from a syscall/trap. */
bralid r15, schedule; /* Call scheduler */
nop; /* delay slot */
/* XXX Is PT_DTRACE handling needed here? */
/* XXX m68knommu also checks TASK_STATE & TASK_COUNTER here. */
/* Maybe handle a signal */
5: lwi r11, CURRENT_TASK, TS_THREAD_INFO; /* get thread info */
......@@ -818,48 +837,37 @@ dbtrap_call: /* return point for kernel/user entry */
andi r11, r11, _TIF_SIGPENDING;
beqi r11, 1f; /* Signals to handle, handle them */
/* Handle a signal return; Pending signals should be in r18. */
/* Not all registers are saved by the normal trap/interrupt entry
points (for instance, call-saved registers (because the normal
C-compiler calling sequence in the kernel makes sure they're
preserved), and call-clobbered registers in the case of
traps), but signal handlers may want to examine or change the
complete register state. Here we save anything not saved by
the normal entry sequence, so that it may be safely restored
(in a possibly modified form) after do_signal returns. */
addik r5, r1, PTO; /* Arg 1: struct pt_regs *regs */
addi r7, r0, 0; /* Arg 3: int in_syscall */
bralid r15, do_signal; /* Handle any signals */
add r6, r0, r0; /* Arg 2: sigset_t *oldset */
/* Finally, return to user state. */
1:
swi CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
1: swi CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
VM_OFF;
tophys(r1,r1);
/* MS: Restore all regs */
RESTORE_REGS
lwi r17, r1, PTO+PT_R17;
lwi r16, r1, PTO+PT_R16;
addik r1, r1, STATE_SAVE_SIZE /* Clean up stack space. */
lwi r1, r1, PT_R1 - PT_SIZE;
/* Restore user stack pointer. */
bri 6f;
addik r1, r1, STATE_SAVE_SIZE /* Clean up stack space */
lwi r1, r1, PT_R1 - PT_SIZE; /* Restore user stack pointer */
DBTRAP_return_user: /* MS: Make global symbol for debugging */
rtbd r16, 0; /* MS: Instructions to return from a debug trap */
nop;
/* Return to kernel state. */
/* MS: Return to kernel state - kgdb */
2: VM_OFF;
tophys(r1,r1);
/* MS: Restore all regs */
RESTORE_REGS
addik r1, r1, STATE_SAVE_SIZE /* Clean up stack space. */
lwi r14, r1, PTO+PT_R14;
lwi r16, r1, PTO+PT_PC;
lwi r17, r1, PTO+PT_R17;
addik r1, r1, STATE_SAVE_SIZE; /* MS: Clean up stack space */
tovirt(r1,r1);
6:
DBTRAP_return: /* Make global symbol for debugging */
rtbd r16, 0; /* Instructions to return from an IRQ */
DBTRAP_return_kernel: /* MS: Make global symbol for debugging */
rtbd r16, 0; /* MS: Instructions to return from a debug trap */
nop;
......
......@@ -59,7 +59,6 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
siginfo_t info;
if (kernel_mode(regs)) {
debugger(regs);
die("Exception in kernel mode", regs, signr);
}
info.si_signo = signr;
......
/*
* Microblaze KGDB support
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kgdb.h>
#include <linux/kdebug.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <asm/cacheflush.h>
#include <asm/asm-offsets.h>
#include <asm/pvr.h>
#define GDB_REG 0
#define GDB_PC 32
#define GDB_MSR 33
#define GDB_EAR 34
#define GDB_ESR 35
#define GDB_FSR 36
#define GDB_BTR 37
#define GDB_PVR 38
#define GDB_REDR 50
#define GDB_RPID 51
#define GDB_RZPR 52
#define GDB_RTLBX 53
#define GDB_RTLBSX 54 /* mfs can't read it */
#define GDB_RTLBLO 55
#define GDB_RTLBHI 56
/* keep pvr separately because it is unchangeble */
struct pvr_s pvr;
void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
int i;
unsigned long *pt_regb = (unsigned long *)regs;
int temp;
/* registers r0 - r31, pc, msr, ear, esr, fsr + do not save pt_mode */
for (i = 0; i < (sizeof(struct pt_regs) / 4) - 1; i++)
gdb_regs[i] = pt_regb[i];
/* Branch target register can't be changed */
__asm__ __volatile__ ("mfs %0, rbtr;" : "=r"(temp) : );
gdb_regs[GDB_BTR] = temp;
/* pvr part - we have 11 pvr regs */
for (i = 0; i < sizeof(struct pvr_s)/4; i++)
gdb_regs[GDB_PVR + i] = pvr.pvr[i];
/* read special registers - can't be changed */
__asm__ __volatile__ ("mfs %0, redr;" : "=r"(temp) : );
gdb_regs[GDB_REDR] = temp;
__asm__ __volatile__ ("mfs %0, rpid;" : "=r"(temp) : );
gdb_regs[GDB_RPID] = temp;
__asm__ __volatile__ ("mfs %0, rzpr;" : "=r"(temp) : );
gdb_regs[GDB_RZPR] = temp;
__asm__ __volatile__ ("mfs %0, rtlbx;" : "=r"(temp) : );
gdb_regs[GDB_RTLBX] = temp;
__asm__ __volatile__ ("mfs %0, rtlblo;" : "=r"(temp) : );
gdb_regs[GDB_RTLBLO] = temp;
__asm__ __volatile__ ("mfs %0, rtlbhi;" : "=r"(temp) : );
gdb_regs[GDB_RTLBHI] = temp;
}
void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
int i;
unsigned long *pt_regb = (unsigned long *)regs;
/* pt_regs and gdb_regs have the same 37 values.
* The rest of gdb_regs are unused and can't be changed.
* r0 register value can't be changed too. */
for (i = 1; i < (sizeof(struct pt_regs) / 4) - 1; i++)
pt_regb[i] = gdb_regs[i];
}
void microblaze_kgdb_break(struct pt_regs *regs)
{
if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
return 0;
/* Jump over the first arch_kgdb_breakpoint which is barrier to
* get kgdb work. The same solution is used for powerpc */
if (*(u32 *) (regs->pc) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
regs->pc += BREAK_INSTR_SIZE;
}
/* untested */
void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
int i;
unsigned long *pt_regb = (unsigned long *)(p->thread.regs);
/* registers r0 - r31, pc, msr, ear, esr, fsr + do not save pt_mode */
for (i = 0; i < (sizeof(struct pt_regs) / 4) - 1; i++)
gdb_regs[i] = pt_regb[i];
/* pvr part - we have 11 pvr regs */
for (i = 0; i < sizeof(struct pvr_s)/4; i++)
gdb_regs[GDB_PVR + i] = pvr.pvr[i];
}
void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
{
regs->pc = ip;
}
int kgdb_arch_handle_exception(int vector, int signo, int err_code,
char *remcom_in_buffer, char *remcom_out_buffer,
struct pt_regs *regs)
{
char *ptr;
unsigned long address;
int cpu = smp_processor_id();
switch (remcom_in_buffer[0]) {
case 'c':
/* handle the optional parameter */
ptr = &remcom_in_buffer[1];
if (kgdb_hex2long(&ptr, &address))
regs->pc = address;
return 0;
}
return -1; /* this means that we do not want to exit from the handler */
}
int kgdb_arch_init(void)
{
get_pvr(&pvr); /* Fill PVR structure */
return 0;
}
void kgdb_arch_exit(void)
{
/* Nothing to do */
}
/*
* Global data
*/
struct kgdb_arch arch_kgdb_ops = {
.gdb_bpt_instr = {0xba, 0x0c, 0x00, 0x18}, /* brki r16, 0x18 */
};
......@@ -37,10 +37,6 @@
#include <linux/uaccess.h>
#include <asm/exceptions.h>
#if defined(CONFIG_KGDB)
int debugger_kernel_faults = 1;
#endif
static unsigned long pte_misses; /* updated by do_page_fault() */
static unsigned long pte_errors; /* updated by do_page_fault() */
......@@ -81,10 +77,6 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
}
/* kernel has accessed a bad area */
#if defined(CONFIG_KGDB)
if (debugger_kernel_faults)
debugger(regs);
#endif
die("kernel access of bad area", regs, sig);
}
......@@ -115,13 +107,6 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
if ((error_code & 0x13) == 0x13 || (error_code & 0x11) == 0x11)
is_write = 0;
#if defined(CONFIG_KGDB)
if (debugger_fault_handler && regs->trap == 0x300) {
debugger_fault_handler(regs);
return;
}
#endif /* CONFIG_KGDB */
if (unlikely(in_atomic() || !mm)) {
if (kernel_mode(regs))
goto bad_area_nosemaphore;
......
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