Commit 03fae44b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v4.15-rc9' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace 

Pull tracing fixes from Steven Rostedt:
 "With the new ORC unwinder, ftrace stack tracing became disfunctional.

  One was that ORC didn't know how to handle the ftrace callbacks in
  general (which Josh fixed).

  The other was that ORC would just bail if it hit a dynamically
  allocated trampoline. Which means all ftrace stack tracing that
  happens from the function tracer would produce no results (that
  includes killing the max stack size tracer). I added a check to the
  ORC unwinder to see if the trampoline belonged to ftrace, and if it
  did, use the orc entry of the static trampoline that was used to
  create the dynamic one (it would be identical).

  Finally, I noticed that the skip values of the stack tracing were out
  of whack. I went through and fixed them up"

* tag 'trace-v4.15-rc9' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Update stack trace skipping for ORC unwinder
  ftrace, orc, x86: Handle ftrace dynamically allocated trampolines
  x86/ftrace: Fix ORC unwinding from ftrace handlers
parents ce30f264 2ee5b92a

arch/x86/kernel/Makefile

+4 −1
Original line number Diff line number Diff line
@@ -29,10 +29,13 @@ KASAN_SANITIZE_stacktrace.o := n 
KASAN_SANITIZE_paravirt.o				:= n



OBJECT_FILES_NON_STANDARD_relocate_kernel_$(BITS).o	:= y

OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o		:= y

OBJECT_FILES_NON_STANDARD_test_nx.o			:= y

OBJECT_FILES_NON_STANDARD_paravirt_patch_$(BITS).o	:= y



ifdef CONFIG_FRAME_POINTER

OBJECT_FILES_NON_STANDARD_ftrace_$(BITS).o		:= y

endif



# If instrumentation of this dir is enabled, boot hangs during first second.

# Probably could be more selective here, but note that files related to irqs,

# boot, dumpstack/stacktrace, etc are either non-interesting or can lead to

arch/x86/kernel/ftrace_64.S

+15 −9
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <asm/ftrace.h>

#include <asm/export.h>

#include <asm/nospec-branch.h>

#include <asm/unwind_hints.h>



	.code64

	.section .entry.text, "ax"
@@ -20,7 +21,6 @@ EXPORT_SYMBOL(__fentry__) 
EXPORT_SYMBOL(mcount)

#endif



/* All cases save the original rbp (8 bytes) */

#ifdef CONFIG_FRAME_POINTER

# ifdef CC_USING_FENTRY

/* Save parent and function stack frames (rip and rbp) */
@@ -31,7 +31,7 @@ EXPORT_SYMBOL(mcount) 
# endif

#else

/* No need to save a stack frame */

# define MCOUNT_FRAME_SIZE	8

# define MCOUNT_FRAME_SIZE	0

#endif /* CONFIG_FRAME_POINTER */



/* Size of stack used to save mcount regs in save_mcount_regs */
@@ -64,10 +64,10 @@ EXPORT_SYMBOL(mcount) 
 */

.macro save_mcount_regs added=0



	/* Always save the original rbp */

#ifdef CONFIG_FRAME_POINTER

	/* Save the original rbp */

	pushq %rbp



#ifdef CONFIG_FRAME_POINTER

	/*

	 * Stack traces will stop at the ftrace trampoline if the frame pointer

	 * is not set up properly. If fentry is used, we need to save a frame
@@ -105,7 +105,11 @@ EXPORT_SYMBOL(mcount) 
	 * Save the original RBP. Even though the mcount ABI does not

	 * require this, it helps out callers.

	 */

#ifdef CONFIG_FRAME_POINTER

	movq MCOUNT_REG_SIZE-8(%rsp), %rdx

#else

	movq %rbp, %rdx

#endif

	movq %rdx, RBP(%rsp)



	/* Copy the parent address into %rsi (second parameter) */
@@ -148,7 +152,7 @@ EXPORT_SYMBOL(mcount) 


ENTRY(function_hook)

	retq

END(function_hook)

ENDPROC(function_hook)



ENTRY(ftrace_caller)

	/* save_mcount_regs fills in first two parameters */
@@ -184,7 +188,7 @@ GLOBAL(ftrace_graph_call) 
/* This is weak to keep gas from relaxing the jumps */

WEAK(ftrace_stub)

	retq

END(ftrace_caller)

ENDPROC(ftrace_caller)



ENTRY(ftrace_regs_caller)

	/* Save the current flags before any operations that can change them */
@@ -255,7 +259,7 @@ GLOBAL(ftrace_regs_caller_end) 


	jmp ftrace_epilogue



END(ftrace_regs_caller)

ENDPROC(ftrace_regs_caller)





#else /* ! CONFIG_DYNAMIC_FTRACE */
@@ -313,9 +317,10 @@ ENTRY(ftrace_graph_caller) 
	restore_mcount_regs



	retq

END(ftrace_graph_caller)

ENDPROC(ftrace_graph_caller)



GLOBAL(return_to_handler)

ENTRY(return_to_handler)

	UNWIND_HINT_EMPTY

	subq  $24, %rsp



	/* Save the return values */
@@ -330,4 +335,5 @@ GLOBAL(return_to_handler) 
	movq (%rsp), %rax

	addq $24, %rsp

	JMP_NOSPEC %rdi

END(return_to_handler)

#endif

arch/x86/kernel/unwind_orc.c

+47 −1
Original line number Diff line number Diff line
@@ -74,8 +74,50 @@ static struct orc_entry *orc_module_find(unsigned long ip) 
}

#endif



#ifdef CONFIG_DYNAMIC_FTRACE

static struct orc_entry *orc_find(unsigned long ip);



/*

 * Ftrace dynamic trampolines do not have orc entries of their own.

 * But they are copies of the ftrace entries that are static and

 * defined in ftrace_*.S, which do have orc entries.

 *

 * If the undwinder comes across a ftrace trampoline, then find the

 * ftrace function that was used to create it, and use that ftrace

 * function's orc entrie, as the placement of the return code in

 * the stack will be identical.

 */

static struct orc_entry *orc_ftrace_find(unsigned long ip)

{

	struct ftrace_ops *ops;

	unsigned long caller;



	ops = ftrace_ops_trampoline(ip);

	if (!ops)

		return NULL;



	if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)

		caller = (unsigned long)ftrace_regs_call;

	else

		caller = (unsigned long)ftrace_call;



	/* Prevent unlikely recursion */

	if (ip == caller)

		return NULL;



	return orc_find(caller);

}

#else

static struct orc_entry *orc_ftrace_find(unsigned long ip)

{

	return NULL;

}

#endif



static struct orc_entry *orc_find(unsigned long ip)

{

	static struct orc_entry *orc;



	if (!orc_init)

		return NULL;
@@ -111,7 +153,11 @@ static struct orc_entry *orc_find(unsigned long ip) 
				  __stop_orc_unwind_ip - __start_orc_unwind_ip, ip);



	/* Module lookup: */

	return orc_module_find(ip);

	orc = orc_module_find(ip);

	if (orc)

		return orc;



	return orc_ftrace_find(ip);

}



static void orc_sort_swap(void *_a, void *_b, int size)

include/linux/ftrace.h

+2 −0
Original line number Diff line number Diff line
@@ -332,6 +332,8 @@ extern int ftrace_text_reserved(const void *start, const void *end); 


extern int ftrace_nr_registered_ops(void);



struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr);



bool is_ftrace_trampoline(unsigned long addr);



/*

kernel/trace/ftrace.c

+17 −12
Original line number Diff line number Diff line
@@ -1119,15 +1119,11 @@ static struct ftrace_ops global_ops = { 
};



/*

 * This is used by __kernel_text_address() to return true if the

 * address is on a dynamically allocated trampoline that would

 * not return true for either core_kernel_text() or

 * is_module_text_address().

 * Used by the stack undwinder to know about dynamic ftrace trampolines.

 */

bool is_ftrace_trampoline(unsigned long addr)

struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr)

{

	struct ftrace_ops *op;

	bool ret = false;

	struct ftrace_ops *op = NULL;



	/*

	 * Some of the ops may be dynamically allocated,
@@ -1144,15 +1140,24 @@ bool is_ftrace_trampoline(unsigned long addr) 
		if (op->trampoline && op->trampoline_size)

			if (addr >= op->trampoline &&

			    addr < op->trampoline + op->trampoline_size) {

				ret = true;

				goto out;

				preempt_enable_notrace();

				return op;

			}

	} while_for_each_ftrace_op(op);



 out:

	preempt_enable_notrace();



	return ret;

	return NULL;

}



/*

 * This is used by __kernel_text_address() to return true if the

 * address is on a dynamically allocated trampoline that would

 * not return true for either core_kernel_text() or

 * is_module_text_address().

 */

bool is_ftrace_trampoline(unsigned long addr)

{

	return ftrace_ops_trampoline(addr) != NULL;

}



struct ftrace_page {

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