Re: powerpc: do not use kprobe section to exempt exception handlers

[Michael Ellerman]

On Thu, 2016-15-09 at 14:29:44 UTC, Nicholas Piggin wrote:
> Use the blacklist macros instead. This allows the linker to move
> exception handler functions close to callers and avoids trampolines in
> larger kernels.
> 
> Signed-off-by: Nicholas Piggin 

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/03465f899bdac70d34f6ca447a

cheers

Re: [PATCH] powerpc: do not use kprobe section to exempt exception handlers

[Michael Ellerman]

Nicholas Piggin  writes:

> Use the blacklist macros instead. This allows the linker to move
> exception handler functions close to callers and avoids trampolines in
> larger kernels.

Nice, that's been on my todo list for eva.

Can you do the asm ones too? See _KPROBE() in misc_32/64.S.

cheers

[PATCH] powerpc: do not use kprobe section to exempt exception handlers

[Nicholas Piggin]

Use the blacklist macros instead. This allows the linker to move
exception handler functions close to callers and avoids trampolines in
larger kernels.

Signed-off-by: Nicholas Piggin 
---
 arch/powerpc/include/asm/asm-prototypes.h |  6 +++---
 arch/powerpc/kernel/hw_breakpoint.c   |  9 ++---
 arch/powerpc/kernel/traps.c   | 21 ++---
 arch/powerpc/mm/fault.c   |  4 ++--
 4 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/include/asm/asm-prototypes.h 
b/arch/powerpc/include/asm/asm-prototypes.h
index e71b909..b1c3abe 100644
--- a/arch/powerpc/include/asm/asm-prototypes.h
+++ b/arch/powerpc/include/asm/asm-prototypes.h
@@ -52,8 +52,8 @@ void SMIException(struct pt_regs *regs);
 void handle_hmi_exception(struct pt_regs *regs);
 void instruction_breakpoint_exception(struct pt_regs *regs);
 void RunModeException(struct pt_regs *regs);
-void __kprobes single_step_exception(struct pt_regs *regs);
-void __kprobes program_check_exception(struct pt_regs *regs);
+void single_step_exception(struct pt_regs *regs);
+void program_check_exception(struct pt_regs *regs);
 void alignment_exception(struct pt_regs *regs);
 void StackOverflow(struct pt_regs *regs);
 void nonrecoverable_exception(struct pt_regs *regs);
@@ -70,6 +70,6 @@ void unrecoverable_exception(struct pt_regs *regs);
 void kernel_bad_stack(struct pt_regs *regs);
 void system_reset_exception(struct pt_regs *regs);
 void machine_check_exception(struct pt_regs *regs);
-void __kprobes emulation_assist_interrupt(struct pt_regs *regs);
+void emulation_assist_interrupt(struct pt_regs *regs);
 
 #endif /* _ASM_POWERPC_ASM_PROTOTYPES_H */
diff --git a/arch/powerpc/kernel/hw_breakpoint.c 
b/arch/powerpc/kernel/hw_breakpoint.c
index aec9a1b..9781c69 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -206,7 +206,7 @@ void thread_change_pc(struct task_struct *tsk, struct 
pt_regs *regs)
 /*
  * Handle debug exception notifications.
  */
-int __kprobes hw_breakpoint_handler(struct die_args *args)
+int hw_breakpoint_handler(struct die_args *args)
 {
int rc = NOTIFY_STOP;
struct perf_event *bp;
@@ -290,11 +290,12 @@ out:
rcu_read_unlock();
return rc;
 }
+NOKPROBE_SYMBOL(hw_breakpoint_handler);
 
 /*
  * Handle single-step exceptions following a DABR hit.
  */
-static int __kprobes single_step_dabr_instruction(struct die_args *args)
+static int single_step_dabr_instruction(struct die_args *args)
 {
struct pt_regs *regs = args->regs;
struct perf_event *bp = NULL;
@@ -329,11 +330,12 @@ static int __kprobes single_step_dabr_instruction(struct 
die_args *args)
 
return NOTIFY_STOP;
 }
+NOKPROBE_SYMBOL(single_step_dabr_instruction);
 
 /*
  * Handle debug exception notifications.
  */
-int __kprobes hw_breakpoint_exceptions_notify(
+int hw_breakpoint_exceptions_notify(
struct notifier_block *unused, unsigned long val, void *data)
 {
int ret = NOTIFY_DONE;
@@ -349,6 +351,7 @@ int __kprobes hw_breakpoint_exceptions_notify(
 
return ret;
 }
+NOKPROBE_SYMBOL(hw_breakpoint_exceptions_notify);
 
 /*
  * Release the user breakpoints used by ptrace
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 62859eb..7cbd6cf 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -117,7 +117,7 @@ static int die_owner = -1;
 static unsigned int die_nest_count;
 static int die_counter;
 
-static unsigned __kprobes long oops_begin(struct pt_regs *regs)
+static unsigned long oops_begin(struct pt_regs *regs)
 {
int cpu;
unsigned long flags;
@@ -144,8 +144,9 @@ static unsigned __kprobes long oops_begin(struct pt_regs 
*regs)
pmac_backlight_unblank();
return flags;
 }
+NOKPROBE_SYMBOL(oops_begin);
 
-static void __kprobes oops_end(unsigned long flags, struct pt_regs *regs,
+static void oops_end(unsigned long flags, struct pt_regs *regs,
   int signr)
 {
bust_spinlocks(0);
@@ -196,8 +197,9 @@ static void __kprobes oops_end(unsigned long flags, struct 
pt_regs *regs,
panic("Fatal exception");
do_exit(signr);
 }
+NOKPROBE_SYMBOL(oops_end);
 
-static int __kprobes __die(const char *str, struct pt_regs *regs, long err)
+static int __die(const char *str, struct pt_regs *regs, long err)
 {
printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
 #ifdef CONFIG_PREEMPT
@@ -221,6 +223,7 @@ static int __kprobes __die(const char *str, struct pt_regs 
*regs, long err)
 
return 0;
 }
+NOKPROBE_SYMBOL(__die);
 
 void die(const char *str, struct pt_regs *regs, long err)
 {
@@ -802,7 +805,7 @@ void RunModeException(struct pt_regs *regs)
_exception(SIGTRAP, regs, 0, 0);
 }
 
-void __kprobes single_step_exception(struct pt_regs *regs)
+void single_step_exception(struct pt_regs *regs)
 {
enum ctx_state prev_state = exception_enter();