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Subject[PATCH v3 2/2] MIPS: Use NOKPROBE_SYMBOL() instead of __kprobes annotation
Date
If define CONFIG_KPROBES, __kprobes annotation forces the whole function
into the ".kprobes.text" section, NOKPROBE_SYMBOL() only stores the given
function address in the "_kprobe_blacklist" section which is introduced
to maintain kprobes blacklist.

Modify the related code to use NOKPROBE_SYMBOL() to protect functions from
kprobes instead of __kprobes annotation under arch/mips.

No obvious functional change in this patch, some more work needs to be done
to fix the kernel panic when execute the following testcase on mips:

# cd tools/testing/selftests/ftrace
# ./ftracetest test.d/kprobe/multiple_kprobes.tc

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
arch/mips/kernel/kprobes.c | 36 ++++++++++++++++++++++++------------
arch/mips/mm/fault.c | 6 ++++--
2 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index 6c7f3b1..316b27d 100644
--- a/arch/mips/kernel/kprobes.c
+++ b/arch/mips/kernel/kprobes.c
@@ -44,10 +44,11 @@ static const union mips_instruction breakpoint2_insn = {
DEFINE_PER_CPU(struct kprobe *, current_kprobe);
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);

-static int __kprobes insn_has_delayslot(union mips_instruction insn)
+static int insn_has_delayslot(union mips_instruction insn)
{
return __insn_has_delay_slot(insn);
}
+NOKPROBE_SYMBOL(insn_has_delayslot);

/*
* insn_has_ll_or_sc function checks whether instruction is ll or sc
@@ -56,7 +57,7 @@ static int __kprobes insn_has_delayslot(union mips_instruction insn)
* instructions; cannot do much about breakpoint in the middle of
* ll/sc pair; it is upto user to avoid those places
*/
-static int __kprobes insn_has_ll_or_sc(union mips_instruction insn)
+static int insn_has_ll_or_sc(union mips_instruction insn)
{
int ret = 0;

@@ -72,8 +73,9 @@ static int __kprobes insn_has_ll_or_sc(union mips_instruction insn)
}
return ret;
}
+NOKPROBE_SYMBOL(insn_has_ll_or_sc);

-int __kprobes arch_prepare_kprobe(struct kprobe *p)
+int arch_prepare_kprobe(struct kprobe *p)
{
union mips_instruction insn;
union mips_instruction prev_insn;
@@ -132,26 +134,30 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
out:
return ret;
}
+NOKPROBE_SYMBOL(arch_prepare_kprobe);

-void __kprobes arch_arm_kprobe(struct kprobe *p)
+void arch_arm_kprobe(struct kprobe *p)
{
*p->addr = breakpoint_insn;
flush_insn_slot(p);
}
+NOKPROBE_SYMBOL(arch_arm_kprobe);

-void __kprobes arch_disarm_kprobe(struct kprobe *p)
+void arch_disarm_kprobe(struct kprobe *p)
{
*p->addr = p->opcode;
flush_insn_slot(p);
}
+NOKPROBE_SYMBOL(arch_disarm_kprobe);

-void __kprobes arch_remove_kprobe(struct kprobe *p)
+void arch_remove_kprobe(struct kprobe *p)
{
if (p->ainsn.insn) {
free_insn_slot(p->ainsn.insn, 0);
p->ainsn.insn = NULL;
}
}
+NOKPROBE_SYMBOL(arch_remove_kprobe);

static void save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
@@ -257,7 +263,7 @@ static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
* breakpoint trap. In case of branch instructions, the target
* epc to be restored.
*/
-static void __kprobes resume_execution(struct kprobe *p,
+static void resume_execution(struct kprobe *p,
struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
@@ -268,8 +274,9 @@ static void __kprobes resume_execution(struct kprobe *p,
regs->cp0_epc = orig_epc + 4;
}
}
+NOKPROBE_SYMBOL(resume_execution);

-static int __kprobes kprobe_handler(struct pt_regs *regs)
+static int kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p;
int ret = 0;
@@ -367,6 +374,7 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
return ret;

}
+NOKPROBE_SYMBOL(kprobe_handler);

static inline int post_kprobe_handler(struct pt_regs *regs)
{
@@ -415,7 +423,7 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
/*
* Wrapper routine for handling exceptions.
*/
-int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
+int kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{

@@ -446,6 +454,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
}
return ret;
}
+NOKPROBE_SYMBOL(kprobe_exceptions_notify);

/*
* Function return probe trampoline:
@@ -469,7 +478,7 @@ static void __used kretprobe_trampoline_holder(void)

void __kretprobe_trampoline(void);

-void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+void arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *) regs->regs[31];
@@ -478,11 +487,12 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
/* Replace the return addr with trampoline addr */
regs->regs[31] = (unsigned long)__kretprobe_trampoline;
}
+NOKPROBE_SYMBOL(arch_prepare_kretprobe);

/*
* Called when the probe at kretprobe trampoline is hit
*/
-static int __kprobes trampoline_probe_handler(struct kprobe *p,
+static int trampoline_probe_handler(struct kprobe *p,
struct pt_regs *regs)
{
instruction_pointer(regs) = __kretprobe_trampoline_handler(regs, NULL);
@@ -493,14 +503,16 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
*/
return 1;
}
+NOKPROBE_SYMBOL(trampoline_probe_handler);

-int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+int arch_trampoline_kprobe(struct kprobe *p)
{
if (p->addr == (kprobe_opcode_t *)__kretprobe_trampoline)
return 1;

return 0;
}
+NOKPROBE_SYMBOL(arch_trampoline_kprobe);

static struct kprobe trampoline_p = {
.addr = (kprobe_opcode_t *)__kretprobe_trampoline,
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 44f9810..b08bc55 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -35,7 +35,7 @@ int show_unhandled_signals = 1;
* and the problem, and then passes it off to one of the appropriate
* routines.
*/
-static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
+static void __do_page_fault(struct pt_regs *regs, unsigned long write,
unsigned long address)
{
struct vm_area_struct * vma = NULL;
@@ -322,8 +322,9 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
}
#endif
}
+NOKPROBE_SYMBOL(__do_page_fault);

-asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+asmlinkage void do_page_fault(struct pt_regs *regs,
unsigned long write, unsigned long address)
{
enum ctx_state prev_state;
@@ -332,3 +333,4 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
__do_page_fault(regs, write, address);
exception_exit(prev_state);
}
+NOKPROBE_SYMBOL(do_page_fault);
--
2.1.0
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