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

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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: 3c516f89e1 ("x86: Add support for CONFIG_CFI_CLANG")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/Y06dg4e1xF6JTdQq@hirez.programming.kicks-ass.net
This commit is contained in:
Peter Zijlstra 2022-10-18 13:49:21 +02:00
parent b5f1fc3184
commit 883bbbffa5
3 changed files with 27 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/arm64/kernel/entry-ftrace.S
View File

@ -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)

17
arch/x86/kernel/ftrace_64.S
View File

@ -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:

18
include/asm-generic/vmlinux.lds.h
View File

@ -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()