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Subject[PATCH 1/2] kgdb: fix several kgdb regressions
Date
kgdb core fixes:
- Check to see that mm->mmap_cache is not null before calling
flush_cache_range(), else on arch=ARM it will cause a fatal
fault.

- Breakpoints should only be restored if they are in the BP_ACTIVE
state.

- Fix a typo in comments to "kgdb_register_io_module"

x86 kgdb fixes:
- Fix the x86 arch handler such that on a kill or detach that the
appropriate cleanup on the single stepping flags gets run.

- Add in the DIE_NMIWATCHDOG call for x86_64

- Touch the nmi watchdog before returning the system to normal
operation after performing any kind of kgdb operation, else
the possibility exists to trigger the watchdog.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
arch/x86/kernel/kgdb.c | 4 ++++
arch/x86/kernel/traps_64.c | 7 ++++++-
kernel/kgdb.c | 14 ++++++++------
3 files changed, 18 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 7d651ad..8c7e555 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -370,6 +370,8 @@ int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
ptr = &remcomInBuffer[1];
if (kgdb_hex2long(&ptr, &addr))
linux_regs->ip = addr;
+ case 'D':
+ case 'k':
newPC = linux_regs->ip;

/* clear the trace bit */
@@ -480,6 +482,8 @@ static int __kgdb_notify(struct die_args *args, unsigned long cmd)
if (kgdb_handle_exception(args->trapnr, args->signr, args->err, regs))
return NOTIFY_DONE;

+ /* Must touch watchdog before return to normal operation */
+ touch_nmi_watchdog();
return NOTIFY_STOP;
}

diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 055b165..4e07332 100644
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -600,8 +600,13 @@ void die(const char * str, struct pt_regs * regs, long err)

void __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
{
- unsigned long flags = oops_begin();
+ unsigned long flags;
+
+ if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, 2, SIGINT) ==
+ NOTIFY_STOP)
+ return;

+ flags = oops_begin();
/*
* We are in trouble anyway, lets at least try
* to get a message out.
diff --git a/kernel/kgdb.c b/kernel/kgdb.c
index 31425e0..85b7e5b 100644
--- a/kernel/kgdb.c
+++ b/kernel/kgdb.c
@@ -600,7 +600,7 @@ static void kgdb_flush_swbreak_addr(unsigned long addr)
if (!CACHE_FLUSH_IS_SAFE)
return;

- if (current->mm) {
+ if (current->mm && current->mm->mmap_cache) {
flush_cache_range(current->mm->mmap_cache,
addr, addr + BREAK_INSTR_SIZE);
} else {
@@ -729,14 +729,16 @@ int remove_all_break(void)

/* Clear memory breakpoints. */
for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) {
- if (kgdb_break[i].state != BP_SET)
- continue;
+ if (kgdb_break[i].state != BP_ACTIVE)
+ goto setundefined;
addr = kgdb_break[i].bpt_addr;
error = kgdb_arch_remove_breakpoint(addr,
kgdb_break[i].saved_instr);
if (error)
- return error;
- kgdb_break[i].state = BP_REMOVED;
+ printk(KERN_ERR "KGDB: breakpoint remove failed: %lx\n",
+ addr);
+setundefined:
+ kgdb_break[i].state = BP_UNDEFINED;
}

/* Clear hardware breakpoints. */
@@ -1605,7 +1607,7 @@ static void kgdb_initial_breakpoint(void)
}

/**
- * kkgdb_register_io_module - register KGDB IO module
+ * kgdb_register_io_module - register KGDB IO module
* @new_kgdb_io_ops: the io ops vector
*
* Register it with the KGDB core.
--
1.5.4


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