Commit 883bbbff authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

ftrace,kcfi: Separate ftrace_stub() and ftrace_stub_graph() 



Different function signatures means they needs to be different
functions; otherwise CFI gets upset.

As triggered by the ftrace boot tests:

  [] CFI failure at ftrace_return_to_handler+0xac/0x16c (target: ftrace_stub+0x0/0x14; expected type: 0x0a5d5347)

Fixes: 3c516f89 ("x86: Add support for CONFIG_CFI_CLANG")
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by: default avatarMark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/Y06dg4e1xF6JTdQq@hirez.programming.kicks-ass.net
parent b5f1fc31

arch/arm64/kernel/entry-ftrace.S

+6 −1
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
 */



#include <linux/linkage.h>

#include <linux/cfi_types.h>

#include <asm/asm-offsets.h>

#include <asm/assembler.h>

#include <asm/ftrace.h>
@@ -294,10 +295,14 @@ SYM_FUNC_END(ftrace_graph_caller) 
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */



SYM_FUNC_START(ftrace_stub)

SYM_TYPED_FUNC_START(ftrace_stub)

	ret

SYM_FUNC_END(ftrace_stub)



SYM_TYPED_FUNC_START(ftrace_stub_graph)

	ret

SYM_FUNC_END(ftrace_stub_graph)



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

/*

 * void return_to_handler(void)

arch/x86/kernel/ftrace_64.S

+9 −8
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
 */



#include <linux/linkage.h>

#include <linux/cfi_types.h>

#include <asm/ptrace.h>

#include <asm/ftrace.h>

#include <asm/export.h>
@@ -129,6 +130,14 @@ 


	.endm



SYM_TYPED_FUNC_START(ftrace_stub)

	RET

SYM_FUNC_END(ftrace_stub)



SYM_TYPED_FUNC_START(ftrace_stub_graph)

	RET

SYM_FUNC_END(ftrace_stub_graph)



#ifdef CONFIG_DYNAMIC_FTRACE



SYM_FUNC_START(__fentry__)
@@ -176,11 +185,6 @@ SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL) 
SYM_FUNC_END(ftrace_caller);

STACK_FRAME_NON_STANDARD_FP(ftrace_caller)



SYM_FUNC_START(ftrace_stub)

	UNWIND_HINT_FUNC

	RET

SYM_FUNC_END(ftrace_stub)



SYM_FUNC_START(ftrace_regs_caller)

	/* Save the current flags before any operations that can change them */

	pushfq
@@ -282,9 +286,6 @@ STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller) 
SYM_FUNC_START(__fentry__)

	cmpq $ftrace_stub, ftrace_trace_function

	jnz trace



SYM_INNER_LABEL(ftrace_stub, SYM_L_GLOBAL)

	ENDBR

	RET



trace:

include/asm-generic/vmlinux.lds.h

+12 −6
Original line number Diff line number Diff line
@@ -162,6 +162,16 @@ 
#define PATCHABLE_DISCARDS	*(__patchable_function_entries)

#endif



#ifndef CONFIG_ARCH_SUPPORTS_CFI_CLANG

/*

 * Simply points to ftrace_stub, but with the proper protocol.

 * Defined by the linker script in linux/vmlinux.lds.h

 */

#define	FTRACE_STUB_HACK	ftrace_stub_graph = ftrace_stub;

#else

#define FTRACE_STUB_HACK

#endif



#ifdef CONFIG_FTRACE_MCOUNT_RECORD

/*

 * The ftrace call sites are logged to a section whose name depends on the
@@ -169,10 +179,6 @@ 
 * FTRACE_CALLSITE_SECTION. We capture all of them here to avoid header

 * dependencies for FTRACE_CALLSITE_SECTION's definition.

 *

 * Need to also make ftrace_stub_graph point to ftrace_stub

 * so that the same stub location may have different protocols

 * and not mess up with C verifiers.

 *

 * ftrace_ops_list_func will be defined as arch_ftrace_ops_list_func

 * as some archs will have a different prototype for that function

 * but ftrace_ops_list_func() will have a single prototype.
@@ -182,11 +188,11 @@ 
			KEEP(*(__mcount_loc))			\

			KEEP_PATCHABLE				\

			__stop_mcount_loc = .;			\

			ftrace_stub_graph = ftrace_stub;	\

			FTRACE_STUB_HACK			\

			ftrace_ops_list_func = arch_ftrace_ops_list_func;

#else

# ifdef CONFIG_FUNCTION_TRACER

#  define MCOUNT_REC()	ftrace_stub_graph = ftrace_stub;	\

#  define MCOUNT_REC()	FTRACE_STUB_HACK			\

			ftrace_ops_list_func = arch_ftrace_ops_list_func;

# else

#  define MCOUNT_REC()