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linux_dsm_epyc7002/arch/tile/kernel/kgdb.c
Chris Metcalf 77ef8f5177 tile kgdb: fix bug in copy to gdb regs, and optimize memset 
David Binderman pointed out that we were doing a full memset()
of the gdb register buffer and then doing a memcpy() to it that
was almost as big.  This commit optimizes that by only doing a
memset() of the registers that are intended to be zero.

While making this change I noticed that we were not copying the
link register (LR, number 55) due to a fencepost error in commit
f419e6f63c ("arch: tile: kernel: kgdb.c: Use memcpy() instead of
pointer copy one by one"), and I've corrected that as well.

Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
2016-03-02 15:19:44 -05:00

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/*
* Copyright 2013 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* TILE-Gx KGDB support.
*/
#include <linux/ptrace.h>
#include <linux/kgdb.h>
#include <linux/kdebug.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <asm/cacheflush.h>
static tile_bundle_bits singlestep_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
static unsigned long stepped_addr;
static tile_bundle_bits stepped_instr;
struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
{ "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0])},
{ "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1])},
{ "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2])},
{ "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3])},
{ "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4])},
{ "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5])},
{ "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6])},
{ "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7])},
{ "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8])},
{ "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9])},
{ "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10])},
{ "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11])},
{ "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12])},
{ "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13])},
{ "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14])},
{ "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15])},
{ "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16])},
{ "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17])},
{ "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18])},
{ "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19])},
{ "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20])},
{ "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21])},
{ "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22])},
{ "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23])},
{ "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24])},
{ "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25])},
{ "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26])},
{ "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27])},
{ "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28])},
{ "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29])},
{ "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30])},
{ "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31])},
{ "r32", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[32])},
{ "r33", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[33])},
{ "r34", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[34])},
{ "r35", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[35])},
{ "r36", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[36])},
{ "r37", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[37])},
{ "r38", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[38])},
{ "r39", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[39])},
{ "r40", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[40])},
{ "r41", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[41])},
{ "r42", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[42])},
{ "r43", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[43])},
{ "r44", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[44])},
{ "r45", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[45])},
{ "r46", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[46])},
{ "r47", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[47])},
{ "r48", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[48])},
{ "r49", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[49])},
{ "r50", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[50])},
{ "r51", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[51])},
{ "r52", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[52])},
{ "tp", GDB_SIZEOF_REG, offsetof(struct pt_regs, tp)},
{ "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, sp)},
{ "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, lr)},
{ "sn", GDB_SIZEOF_REG, -1},
{ "idn0", GDB_SIZEOF_REG, -1},
{ "idn1", GDB_SIZEOF_REG, -1},
{ "udn0", GDB_SIZEOF_REG, -1},
{ "udn1", GDB_SIZEOF_REG, -1},
{ "udn2", GDB_SIZEOF_REG, -1},
{ "udn3", GDB_SIZEOF_REG, -1},
{ "zero", GDB_SIZEOF_REG, -1},
{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, pc)},
{ "faultnum", GDB_SIZEOF_REG, offsetof(struct pt_regs, faultnum)},
};
char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
if (regno >= DBG_MAX_REG_NUM || regno < 0)
return NULL;
if (dbg_reg_def[regno].offset != -1)
memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
dbg_reg_def[regno].size);
else
memset(mem, 0, dbg_reg_def[regno].size);
return dbg_reg_def[regno].name;
}
int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
if (regno >= DBG_MAX_REG_NUM || regno < 0)
return -EINVAL;
if (dbg_reg_def[regno].offset != -1)
memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
dbg_reg_def[regno].size);
return 0;
}
/*
* Similar to pt_regs_to_gdb_regs() except that process is sleeping and so
* we may not be able to get all the info.
*/
void
sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
{
struct pt_regs *thread_regs;
const int NGPRS = TREG_LAST_GPR + 1;
if (task == NULL)
return;
thread_regs = task_pt_regs(task);
memcpy(gdb_regs, thread_regs, NGPRS * sizeof(unsigned long));
memset(&gdb_regs[NGPRS], 0,
(TILEGX_PC_REGNUM - NGPRS) * sizeof(unsigned long));
gdb_regs[TILEGX_PC_REGNUM] = thread_regs->pc;
gdb_regs[TILEGX_FAULTNUM_REGNUM] = thread_regs->faultnum;
}
void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
regs->pc = pc;
}
static void kgdb_call_nmi_hook(void *ignored)
{
kgdb_nmicallback(raw_smp_processor_id(), NULL);
}
void kgdb_roundup_cpus(unsigned long flags)
{
local_irq_enable();
smp_call_function(kgdb_call_nmi_hook, NULL, 0);
local_irq_disable();
}
/*
* Convert a kernel address to the writable kernel text mapping.
*/
static unsigned long writable_address(unsigned long addr)
{
unsigned long ret = 0;
if (core_kernel_text(addr))
ret = ktext_writable_addr(addr);
else if (is_module_text_address(addr))
ret = addr;
else
pr_err("Unknown virtual address 0x%lx\n", addr);
return ret;
}
/*
* Calculate the new address for after a step.
*/
static unsigned long get_step_address(struct pt_regs *regs)
{
int src_reg;
int jump_off;
int br_off;
unsigned long addr;
unsigned int opcode;
tile_bundle_bits bundle;
/* Move to the next instruction by default. */
addr = regs->pc + TILEGX_BUNDLE_SIZE_IN_BYTES;
bundle = *(unsigned long *)instruction_pointer(regs);
/* 0: X mode, Otherwise: Y mode. */
if (bundle & TILEGX_BUNDLE_MODE_MASK) {
if (get_Opcode_Y1(bundle) == RRR_1_OPCODE_Y1 &&
get_RRROpcodeExtension_Y1(bundle) ==
UNARY_RRR_1_OPCODE_Y1) {
opcode = get_UnaryOpcodeExtension_Y1(bundle);
switch (opcode) {
case JALR_UNARY_OPCODE_Y1:
case JALRP_UNARY_OPCODE_Y1:
case JR_UNARY_OPCODE_Y1:
case JRP_UNARY_OPCODE_Y1:
src_reg = get_SrcA_Y1(bundle);
dbg_get_reg(src_reg, &addr, regs);
break;
}
}
} else if (get_Opcode_X1(bundle) == RRR_0_OPCODE_X1) {
if (get_RRROpcodeExtension_X1(bundle) ==
UNARY_RRR_0_OPCODE_X1) {
opcode = get_UnaryOpcodeExtension_X1(bundle);
switch (opcode) {
case JALR_UNARY_OPCODE_X1:
case JALRP_UNARY_OPCODE_X1:
case JR_UNARY_OPCODE_X1:
case JRP_UNARY_OPCODE_X1:
src_reg = get_SrcA_X1(bundle);
dbg_get_reg(src_reg, &addr, regs);
break;
}
}
} else if (get_Opcode_X1(bundle) == JUMP_OPCODE_X1) {
opcode = get_JumpOpcodeExtension_X1(bundle);
switch (opcode) {
case JAL_JUMP_OPCODE_X1:
case J_JUMP_OPCODE_X1:
jump_off = sign_extend(get_JumpOff_X1(bundle), 27);
addr = regs->pc +
(jump_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
break;
}
} else if (get_Opcode_X1(bundle) == BRANCH_OPCODE_X1) {
br_off = 0;
opcode = get_BrType_X1(bundle);
switch (opcode) {
case BEQZT_BRANCH_OPCODE_X1:
case BEQZ_BRANCH_OPCODE_X1:
if (get_SrcA_X1(bundle) == 0)
br_off = get_BrOff_X1(bundle);
break;
case BGEZT_BRANCH_OPCODE_X1:
case BGEZ_BRANCH_OPCODE_X1:
if (get_SrcA_X1(bundle) >= 0)
br_off = get_BrOff_X1(bundle);
break;
case BGTZT_BRANCH_OPCODE_X1:
case BGTZ_BRANCH_OPCODE_X1:
if (get_SrcA_X1(bundle) > 0)
br_off = get_BrOff_X1(bundle);
break;
case BLBCT_BRANCH_OPCODE_X1:
case BLBC_BRANCH_OPCODE_X1:
if (!(get_SrcA_X1(bundle) & 1))
br_off = get_BrOff_X1(bundle);
break;
case BLBST_BRANCH_OPCODE_X1:
case BLBS_BRANCH_OPCODE_X1:
if (get_SrcA_X1(bundle) & 1)
br_off = get_BrOff_X1(bundle);
break;
case BLEZT_BRANCH_OPCODE_X1:
case BLEZ_BRANCH_OPCODE_X1:
if (get_SrcA_X1(bundle) <= 0)
br_off = get_BrOff_X1(bundle);
break;
case BLTZT_BRANCH_OPCODE_X1:
case BLTZ_BRANCH_OPCODE_X1:
if (get_SrcA_X1(bundle) < 0)
br_off = get_BrOff_X1(bundle);
break;
case BNEZT_BRANCH_OPCODE_X1:
case BNEZ_BRANCH_OPCODE_X1:
if (get_SrcA_X1(bundle) != 0)
br_off = get_BrOff_X1(bundle);
break;
}
if (br_off != 0) {
br_off = sign_extend(br_off, 17);
addr = regs->pc +
(br_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
}
}
return addr;
}
/*
* Replace the next instruction after the current instruction with a
* breakpoint instruction.
*/
static void do_single_step(struct pt_regs *regs)
{
unsigned long addr_wr;
/* Determine where the target instruction will send us to. */
stepped_addr = get_step_address(regs);
probe_kernel_read((char *)&stepped_instr, (char *)stepped_addr,
BREAK_INSTR_SIZE);
addr_wr = writable_address(stepped_addr);
probe_kernel_write((char *)addr_wr, (char *)&singlestep_insn,
BREAK_INSTR_SIZE);
smp_wmb();
flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
}
static void undo_single_step(struct pt_regs *regs)
{
unsigned long addr_wr;
if (stepped_instr == 0)
return;
addr_wr = writable_address(stepped_addr);
probe_kernel_write((char *)addr_wr, (char *)&stepped_instr,
BREAK_INSTR_SIZE);
stepped_instr = 0;
smp_wmb();
flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
}
/*
* Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
* then try to fall into the debugger.
*/
static int
kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
{
int ret;
unsigned long flags;
struct die_args *args = (struct die_args *)ptr;
struct pt_regs *regs = args->regs;
#ifdef CONFIG_KPROBES
/*
* Return immediately if the kprobes fault notifier has set
* DIE_PAGE_FAULT.
*/
if (cmd == DIE_PAGE_FAULT)
return NOTIFY_DONE;
#endif /* CONFIG_KPROBES */
switch (cmd) {
case DIE_BREAK:
case DIE_COMPILED_BPT:
break;
case DIE_SSTEPBP:
local_irq_save(flags);
kgdb_handle_exception(0, SIGTRAP, 0, regs);
local_irq_restore(flags);
return NOTIFY_STOP;
default:
/* Userspace events, ignore. */
if (user_mode(regs))
return NOTIFY_DONE;
}
local_irq_save(flags);
ret = kgdb_handle_exception(args->trapnr, args->signr, args->err, regs);
local_irq_restore(flags);
if (ret)
return NOTIFY_DONE;
return NOTIFY_STOP;
}
static struct notifier_block kgdb_notifier = {
.notifier_call = kgdb_notify,
};
/*
* kgdb_arch_handle_exception - Handle architecture specific GDB packets.
* @vector: The error vector of the exception that happened.
* @signo: The signal number of the exception that happened.
* @err_code: The error code of the exception that happened.
* @remcom_in_buffer: The buffer of the packet we have read.
* @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
* @regs: The &struct pt_regs of the current process.
*
* This function MUST handle the 'c' and 's' command packets,
* as well packets to set / remove a hardware breakpoint, if used.
* If there are additional packets which the hardware needs to handle,
* they are handled here. The code should return -1 if it wants to
* process more packets, and a %0 or %1 if it wants to exit from the
* kgdb callback.
*/
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;
/* Undo any stepping we may have done. */
undo_single_step(regs);
switch (remcom_in_buffer[0]) {
case 'c':
case 's':
case 'D':
case 'k':
/*
* Try to read optional parameter, pc unchanged if no parm.
* If this was a compiled-in breakpoint, we need to move
* to the next instruction or we will just breakpoint
* over and over again.
*/
ptr = &remcom_in_buffer[1];
if (kgdb_hex2long(&ptr, &address))
regs->pc = address;
else if (*(unsigned long *)regs->pc == compiled_bpt)
regs->pc += BREAK_INSTR_SIZE;
if (remcom_in_buffer[0] == 's') {
do_single_step(regs);
kgdb_single_step = 1;
atomic_set(&kgdb_cpu_doing_single_step,
raw_smp_processor_id());
} else
atomic_set(&kgdb_cpu_doing_single_step, -1);
return 0;
}
return -1; /* this means that we do not want to exit from the handler */
}
struct kgdb_arch arch_kgdb_ops;
/*
* kgdb_arch_init - Perform any architecture specific initalization.
*
* This function will handle the initalization of any architecture
* specific callbacks.
*/
int kgdb_arch_init(void)
{
tile_bundle_bits bundle = TILEGX_BPT_BUNDLE;
memcpy(arch_kgdb_ops.gdb_bpt_instr, &bundle, BREAK_INSTR_SIZE);
return register_die_notifier(&kgdb_notifier);
}
/*
* kgdb_arch_exit - Perform any architecture specific uninitalization.
*
* This function will handle the uninitalization of any architecture
* specific callbacks, for dynamic registration and unregistration.
*/
void kgdb_arch_exit(void)
{
unregister_die_notifier(&kgdb_notifier);
}
int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
{
int err;
unsigned long addr_wr = writable_address(bpt->bpt_addr);
if (addr_wr == 0)
return -1;
err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
BREAK_INSTR_SIZE);
if (err)
return err;
err = probe_kernel_write((char *)addr_wr, arch_kgdb_ops.gdb_bpt_instr,
BREAK_INSTR_SIZE);
smp_wmb();
flush_icache_range((unsigned long)bpt->bpt_addr,
(unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
return err;
}
int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
{
int err;
unsigned long addr_wr = writable_address(bpt->bpt_addr);
if (addr_wr == 0)
return -1;
err = probe_kernel_write((char *)addr_wr, (char *)bpt->saved_instr,
BREAK_INSTR_SIZE);
smp_wmb();
flush_icache_range((unsigned long)bpt->bpt_addr,
(unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
return err;
}
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