Re: [PATCH 2/2] MIPS: Use NOKPROBE_SYMBOL() instead of __kprobes annotation

6 May 2022

On Thu,  5 May 2022 20:19:08 +0800
Tiezhu Yang yangtiezhu@loongson.cn wrote:
...
If define CONFIG_KPROBES, __kprobes annotation forces the whole function
into the ".kprobes.text" section, NOKPROBE_SYMBOL() just 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.
So you added some non '__kprobes' annotated functions to NOKPROBE_SYMBOL()
in this patch. Those caused the kernel panic, right? If so, please add such
comment on this description too. Or, split this into 2 patches, one fixes
the kernel panic by adding those functions to NOKPROBE_SYMBOL() and the
other is replacing __kprobes with NOKPROBE_SYMBOL().
Also, could you also find the commit which introduces the kernel panic?
It is worth to backport such fix to stable trees.
Thank you,
...
Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn
arch/mips/kernel/kprobes.c | 45 ++++++++++++++++++++++++++++++++-------------
 arch/mips/mm/fault.c       |  6 ++++--
 2 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index 6c7f3b1..21f9cec 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)
 {
@@ -161,6 +167,7 @@ static void save_previous_kprobe(struct kprobe_ctlblk *kcb)
   kcb->prev_kprobe.saved_SR = kcb->kprobe_saved_SR;
   kcb->prev_kprobe.saved_epc = kcb->kprobe_saved_epc;
 }
+NOKPROBE_SYMBOL(save_previous_kprobe);
 
 static void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
 {
@@ -170,6 +177,7 @@ static void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
   kcb->kprobe_saved_SR = kcb->prev_kprobe.saved_SR;
   kcb->kprobe_saved_epc = kcb->prev_kprobe.saved_epc;
 }
+NOKPROBE_SYMBOL(restore_previous_kprobe);
 
 static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
   		       struct kprobe_ctlblk *kcb)
@@ -178,6 +186,7 @@ static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
   kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE);
   kcb->kprobe_saved_epc = regs->cp0_epc;
 }
+NOKPROBE_SYMBOL(set_current_kprobe);
 
 /**

evaluate_branch_instrucion -

@@ -225,6 +234,7 @@ static int evaluate_branch_instruction(struct kprobe *p, struct pt_regs *regs,
   return -EFAULT;
 
 }
+NOKPROBE_SYMBOL(evaluate_branch_instruction);
 
 static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
   					struct kprobe_ctlblk *kcb)
@@ -244,6 +254,7 @@ static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs,
   }
   regs->cp0_epc = (unsigned long)&p->ainsn.insn[0];
 }
+NOKPROBE_SYMBOL(prepare_singlestep);
 
 /*

Called after single-stepping.  p->addr is the address of the

@@ -257,7 +268,7 @@ 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 +279,9 @@ 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;
@@ -367,8 +379,9 @@ 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)
+static int post_kprobe_handler(struct pt_regs *regs)
 {
   struct kprobe *cur = kprobe_running();
   struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -396,6 +409,7 @@ static inline int post_kprobe_handler(struct pt_regs *regs)
 
   return 1;
 }
+NOKPROBE_SYMBOL(post_kprobe_handler);
 
 int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
@@ -411,11 +425,12 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
   }
   return 0;
 }
+NOKPROBE_SYMBOL(kprobe_fault_handler);
 
 /*

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 +461,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
   }
   return ret;
 }
+NOKPROBE_SYMBOL(kprobe_exceptions_notify);
 
 /*

Function return probe trampoline:

@@ -469,7 +485,7 @@ 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 +494,12 @@ 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 +510,16 @@ 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
-- 
Masami Hiramatsu mhiramat@kernel.org

    

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Re: [PATCH 2/2] MIPS: Use NOKPROBE_SYMBOL() instead of __kprobes annotation

Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn

+NOKPROBE_SYMBOL(do_page_fault);