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objtool changes for v5.10: 

- Most of the changes are cleanups and reorganization to make the objtool code
    more arch-agnostic. This is in preparation for non-x86 support.
 
 Fixes:
 
  - KASAN fixes.
  - Handle unreachable trap after call to noreturn functions better.
  - Ignore unreachable fake jumps.
  - Misc smaller fixes & cleanups.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'objtool-core-2020-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:
 "Most of the changes are cleanups and reorganization to make the
  objtool code more arch-agnostic. This is in preparation for non-x86
  support.

  Other changes:

   - KASAN fixes

   - Handle unreachable trap after call to noreturn functions better

   - Ignore unreachable fake jumps

   - Misc smaller fixes & cleanups"

* tag 'objtool-core-2020-10-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  perf build: Allow nested externs to enable BUILD_BUG() usage
  objtool: Allow nested externs to enable BUILD_BUG()
  objtool: Permit __kasan_check_{read,write} under UACCESS
  objtool: Ignore unreachable trap after call to noreturn functions
  objtool: Handle calling non-function symbols in other sections
  objtool: Ignore unreachable fake jumps
  objtool: Remove useless tests before save_reg()
  objtool: Decode unwind hint register depending on architecture
  objtool: Make unwind hint definitions available to other architectures
  objtool: Only include valid definitions depending on source file type
  objtool: Rename frame.h -> objtool.h
  objtool: Refactor jump table code to support other architectures
  objtool: Make relocation in alternative handling arch dependent
  objtool: Abstract alternative special case handling
  objtool: Move macros describing structures to arch-dependent code
  objtool: Make sync-check consider the target architecture
  objtool: Group headers to check in a single list
  objtool: Define 'struct orc_entry' only when needed
  objtool: Skip ORC entry creation for non-text sections
  objtool: Move ORC logic out of check()
  ...
This commit is contained in:
Linus Torvalds 2020-10-14 10:13:37 -07:00
parent d5660df4a5 ab0a40ea88
commit 6873139ed0
38 changed files with 686 additions and 411 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
MAINTAINERS
View File

@ -12515,6 +12515,7 @@ M: Josh Poimboeuf <jpoimboe@redhat.com>
M: Peter Zijlstra <peterz@infradead.org>
S: Supported
F: tools/objtool/
F: include/linux/objtool.h
OCELOT ETHERNET SWITCH DRIVER
M: Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>

2
arch/x86/include/asm/nospec-branch.h
View File

@ -4,7 +4,7 @@
#define _ASM_X86_NOSPEC_BRANCH_H_
#include <linux/static_key.h>
#include <linux/frame.h>
#include <linux/objtool.h>
#include <asm/alternative.h>
#include <asm/alternative-asm.h>

34
arch/x86/include/asm/orc_types.h
View File

@ -39,27 +39,6 @@
#define ORC_REG_SP_INDIRECT 9
#define ORC_REG_MAX 15
/*
* ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the
* caller's SP right before it made the call). Used for all callable
* functions, i.e. all C code and all callable asm functions.
*
* ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points
* to a fully populated pt_regs from a syscall, interrupt, or exception.
*
* ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset
* points to the iret return frame.
*
* The UNWIND_HINT macros are used only for the unwind_hint struct. They
* aren't used in struct orc_entry due to size and complexity constraints.
* Objtool converts them to real types when it converts the hints to orc
* entries.
*/
#define ORC_TYPE_CALL 0
#define ORC_TYPE_REGS 1
#define ORC_TYPE_REGS_IRET 2
#define UNWIND_HINT_TYPE_RET_OFFSET 3
#ifndef __ASSEMBLY__
/*
* This struct is more or less a vastly simplified version of the DWARF Call
@ -78,19 +57,6 @@ struct orc_entry {
unsigned end:1;
} __packed;
/*
* This struct is used by asm and inline asm code to manually annotate the
* location of registers on the stack for the ORC unwinder.
*
* Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*.
*/
struct unwind_hint {
u32 ip;
s16 sp_offset;
u8 sp_reg;
u8 type;
u8 end;
};
#endif /* __ASSEMBLY__ */
#endif /* _ORC_TYPES_H */

56
arch/x86/include/asm/unwind_hints.h
View File

@ -1,51 +1,17 @@
#ifndef _ASM_X86_UNWIND_HINTS_H
#define _ASM_X86_UNWIND_HINTS_H
#include <linux/objtool.h>
#include "orc_types.h"
#ifdef __ASSEMBLY__
/*
* In asm, there are two kinds of code: normal C-type callable functions and
* the rest. The normal callable functions can be called by other code, and
* don't do anything unusual with the stack. Such normal callable functions
* are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
* category. In this case, no special debugging annotations are needed because
* objtool can automatically generate the ORC data for the ORC unwinder to read
* at runtime.
*
* Anything which doesn't fall into the above category, such as syscall and
* interrupt handlers, tends to not be called directly by other functions, and
* often does unusual non-C-function-type things with the stack pointer. Such
* code needs to be annotated such that objtool can understand it. The
* following CFI hint macros are for this type of code.
*
* These macros provide hints to objtool about the state of the stack at each
* instruction. Objtool starts from the hints and follows the code flow,
* making automatic CFI adjustments when it sees pushes and pops, filling out
* the debuginfo as necessary. It will also warn if it sees any
* inconsistencies.
*/
.macro UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=0 type=ORC_TYPE_CALL end=0
#ifdef CONFIG_STACK_VALIDATION
.Lunwind_hint_ip_\@:
.pushsection .discard.unwind_hints
/* struct unwind_hint */
.long .Lunwind_hint_ip_\@ - .
.short \sp_offset
.byte \sp_reg
.byte \type
.byte \end
.balign 4
.popsection
#endif
.endm
.macro UNWIND_HINT_EMPTY
UNWIND_HINT sp_reg=ORC_REG_UNDEFINED end=1
UNWIND_HINT sp_reg=ORC_REG_UNDEFINED type=UNWIND_HINT_TYPE_CALL end=1
.endm
.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 iret=0
.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 partial=0
.if \base == %rsp
.if \indirect
.set sp_reg, ORC_REG_SP_INDIRECT
@ -66,24 +32,24 @@
.set sp_offset, \offset
.if \iret
.set type, ORC_TYPE_REGS_IRET
.if \partial
.set type, UNWIND_HINT_TYPE_REGS_PARTIAL
.elseif \extra == 0
.set type, ORC_TYPE_REGS_IRET
.set type, UNWIND_HINT_TYPE_REGS_PARTIAL
.set sp_offset, \offset + (16*8)
.else
.set type, ORC_TYPE_REGS
.set type, UNWIND_HINT_TYPE_REGS
.endif
UNWIND_HINT sp_reg=sp_reg sp_offset=sp_offset type=type
.endm
.macro UNWIND_HINT_IRET_REGS base=%rsp offset=0
UNWIND_HINT_REGS base=\base offset=\offset iret=1
UNWIND_HINT_REGS base=\base offset=\offset partial=1
.endm
.macro UNWIND_HINT_FUNC sp_offset=8
UNWIND_HINT sp_offset=\sp_offset
UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=\sp_offset type=UNWIND_HINT_TYPE_CALL
.endm
/*
@ -92,7 +58,7 @@
* initial_func_cfi.
*/
.macro UNWIND_HINT_RET_OFFSET sp_offset=8
UNWIND_HINT type=UNWIND_HINT_TYPE_RET_OFFSET sp_offset=\sp_offset
UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_RET_OFFSET sp_offset=\sp_offset
.endm
#endif /* __ASSEMBLY__ */

2
arch/x86/kernel/kprobes/core.c
View File

@ -38,9 +38,9 @@
#include <linux/kdebug.h>
#include <linux/kallsyms.h>
#include <linux/ftrace.h>
#include <linux/frame.h>
#include <linux/kasan.h>
#include <linux/moduleloader.h>
#include <linux/objtool.h>
#include <linux/vmalloc.h>
#include <linux/pgtable.h>

2
arch/x86/kernel/kprobes/opt.c
View File

@ -16,7 +16,7 @@
#include <linux/kdebug.h>
#include <linux/kallsyms.h>
#include <linux/ftrace.h>
#include <linux/frame.h>
#include <linux/objtool.h>
#include <linux/pgtable.h>
#include <linux/static_call.h>

2
arch/x86/kernel/reboot.c
View File

@ -10,7 +10,7 @@
#include <linux/sched.h>
#include <linux/tboot.h>
#include <linux/delay.h>
#include <linux/frame.h>
#include <linux/objtool.h>
#include <linux/pgtable.h>
#include <acpi/reboot.h>
#include <asm/io.h>

11
arch/x86/kernel/unwind_orc.c
View File

@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/objtool.h>
#include <linux/module.h>
#include <linux/sort.h>
#include <asm/ptrace.h>
@ -127,12 +128,12 @@ static struct orc_entry null_orc_entry = {
.sp_offset = sizeof(long),
.sp_reg = ORC_REG_SP,
.bp_reg = ORC_REG_UNDEFINED,
.type = ORC_TYPE_CALL
.type = UNWIND_HINT_TYPE_CALL
};
/* Fake frame pointer entry -- used as a fallback for generated code */
static struct orc_entry orc_fp_entry = {
.type = ORC_TYPE_CALL,
.type = UNWIND_HINT_TYPE_CALL,
.sp_reg = ORC_REG_BP,
.sp_offset = 16,
.bp_reg = ORC_REG_PREV_SP,
@ -531,7 +532,7 @@ bool unwind_next_frame(struct unwind_state *state)
/* Find IP, SP and possibly regs: */
switch (orc->type) {
case ORC_TYPE_CALL:
case UNWIND_HINT_TYPE_CALL:
ip_p = sp - sizeof(long);
if (!deref_stack_reg(state, ip_p, &state->ip))
@ -546,7 +547,7 @@ bool unwind_next_frame(struct unwind_state *state)
state->signal = false;
break;
case ORC_TYPE_REGS:
case UNWIND_HINT_TYPE_REGS:
if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) {
orc_warn_current("can't access registers at %pB\n",
(void *)orig_ip);
@ -559,7 +560,7 @@ bool unwind_next_frame(struct unwind_state *state)
state->signal = true;
break;
case ORC_TYPE_REGS_IRET:
case UNWIND_HINT_TYPE_REGS_PARTIAL:
if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) {
orc_warn_current("can't access iret registers at %pB\n",
(void *)orig_ip);

2
arch/x86/kvm/svm/svm.c
View File

@ -19,7 +19,7 @@
#include <linux/trace_events.h>
#include <linux/slab.h>
#include <linux/hashtable.h>
#include <linux/frame.h>
#include <linux/objtool.h>
#include <linux/psp-sev.h>
#include <linux/file.h>
#include <linux/pagemap.h>

2
arch/x86/kvm/vmx/nested.c
View File

@ -1,6 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/frame.h>
#include <linux/objtool.h>
#include <linux/percpu.h>
#include <asm/debugreg.h>

2
arch/x86/kvm/vmx/vmx.c
View File

@ -13,7 +13,6 @@
* Yaniv Kamay <yaniv@qumranet.com>
*/
#include <linux/frame.h>
#include <linux/highmem.h>
#include <linux/hrtimer.h>
#include <linux/kernel.h>
@ -22,6 +21,7 @@
#include <linux/moduleparam.h>
#include <linux/mod_devicetable.h>
#include <linux/mm.h>
#include <linux/objtool.h>
#include <linux/sched.h>
#include <linux/sched/smt.h>
#include <linux/slab.h>

2
arch/x86/xen/enlighten_pv.c
View File

@ -32,7 +32,7 @@
#include <linux/pci.h>
#include <linux/gfp.h>
#include <linux/edd.h>
#include <linux/frame.h>
#include <linux/objtool.h>
#include <xen/xen.h>
#include <xen/events.h>

3
drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
View File

@ -24,7 +24,7 @@
*
*/
#include <linux/frame.h>
#include <linux/objtool.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
@ -599,4 +599,3 @@ out_open:
return -EINVAL;
}

35
include/linux/frame.h
View File

@ -1,35 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_FRAME_H
#define _LINUX_FRAME_H
#ifdef CONFIG_STACK_VALIDATION
/*
* This macro marks the given function's stack frame as "non-standard", which
* tells objtool to ignore the function when doing stack metadata validation.
* It should only be used in special cases where you're 100% sure it won't
* affect the reliability of frame pointers and kernel stack traces.
*
* For more information, see tools/objtool/Documentation/stack-validation.txt.
*/
#define STACK_FRAME_NON_STANDARD(func) \
static void __used __section(.discard.func_stack_frame_non_standard) \
*__func_stack_frame_non_standard_##func = func
/*
* This macro indicates that the following intra-function call is valid.
* Any non-annotated intra-function call will cause objtool to issue a warning.
*/
#define ANNOTATE_INTRA_FUNCTION_CALL \
999: \
.pushsection .discard.intra_function_calls; \
.long 999b; \
.popsection;
#else /* !CONFIG_STACK_VALIDATION */
#define STACK_FRAME_NON_STANDARD(func)
#define ANNOTATE_INTRA_FUNCTION_CALL
#endif /* CONFIG_STACK_VALIDATION */
#endif /* _LINUX_FRAME_H */

129
include/linux/objtool.h Normal file
View File

@ -0,0 +1,129 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_OBJTOOL_H
#define _LINUX_OBJTOOL_H
#ifndef __ASSEMBLY__
#include <linux/types.h>
/*
* This struct is used by asm and inline asm code to manually annotate the
* location of registers on the stack.
*/
struct unwind_hint {
u32 ip;
s16 sp_offset;
u8 sp_reg;
u8 type;
u8 end;
};
#endif
/*
* UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
* (the caller's SP right before it made the call). Used for all callable
* functions, i.e. all C code and all callable asm functions.
*
* UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset
* points to a fully populated pt_regs from a syscall, interrupt, or exception.
*
* UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
* sp_reg+sp_offset points to the iret return frame.
*/
#define UNWIND_HINT_TYPE_CALL 0
#define UNWIND_HINT_TYPE_REGS 1
#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
#define UNWIND_HINT_TYPE_RET_OFFSET 3
#ifdef CONFIG_STACK_VALIDATION
#ifndef __ASSEMBLY__
#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
"987: \n\t" \
".pushsection .discard.unwind_hints\n\t" \
/* struct unwind_hint */ \
".long 987b - .\n\t" \
".short " __stringify(sp_offset) "\n\t" \
".byte " __stringify(sp_reg) "\n\t" \
".byte " __stringify(type) "\n\t" \
".byte " __stringify(end) "\n\t" \
".balign 4 \n\t" \
".popsection\n\t"
/*
* This macro marks the given function's stack frame as "non-standard", which
* tells objtool to ignore the function when doing stack metadata validation.
* It should only be used in special cases where you're 100% sure it won't
* affect the reliability of frame pointers and kernel stack traces.
*
* For more information, see tools/objtool/Documentation/stack-validation.txt.
*/
#define STACK_FRAME_NON_STANDARD(func) \
static void __used __section(.discard.func_stack_frame_non_standard) \
*__func_stack_frame_non_standard_##func = func
#else /* __ASSEMBLY__ */
/*
* This macro indicates that the following intra-function call is valid.
* Any non-annotated intra-function call will cause objtool to issue a warning.
*/
#define ANNOTATE_INTRA_FUNCTION_CALL \
999: \
.pushsection .discard.intra_function_calls; \
.long 999b; \
.popsection;
/*
* In asm, there are two kinds of code: normal C-type callable functions and
* the rest. The normal callable functions can be called by other code, and
* don't do anything unusual with the stack. Such normal callable functions
* are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
* category. In this case, no special debugging annotations are needed because
* objtool can automatically generate the ORC data for the ORC unwinder to read
* at runtime.
*
* Anything which doesn't fall into the above category, such as syscall and
* interrupt handlers, tends to not be called directly by other functions, and
* often does unusual non-C-function-type things with the stack pointer. Such
* code needs to be annotated such that objtool can understand it. The
* following CFI hint macros are for this type of code.
*
* These macros provide hints to objtool about the state of the stack at each
* instruction. Objtool starts from the hints and follows the code flow,
* making automatic CFI adjustments when it sees pushes and pops, filling out
* the debuginfo as necessary. It will also warn if it sees any
* inconsistencies.
*/
.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
.Lunwind_hint_ip_\@:
.pushsection .discard.unwind_hints
/* struct unwind_hint */
.long .Lunwind_hint_ip_\@ - .
.short \sp_offset
.byte \sp_reg
.byte \type
.byte \end
.balign 4
.popsection
.endm
#endif /* __ASSEMBLY__ */
#else /* !CONFIG_STACK_VALIDATION */
#ifndef __ASSEMBLY__
#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
"\n\t"
#define STACK_FRAME_NON_STANDARD(func)
#else
#define ANNOTATE_INTRA_FUNCTION_CALL
.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
.endm
#endif
#endif /* CONFIG_STACK_VALIDATION */
#endif /* _LINUX_OBJTOOL_H */

2
kernel/bpf/core.c
View File

@ -25,7 +25,7 @@
#include <linux/moduleloader.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include <linux/frame.h>
#include <linux/objtool.h>
#include <linux/rbtree_latch.h>
#include <linux/kallsyms.h>
#include <linux/rcupdate.h>

2
kernel/kexec_core.c
View File

@ -36,7 +36,7 @@
#include <linux/syscore_ops.h>
#include <linux/compiler.h>
#include <linux/hugetlb.h>
#include <linux/frame.h>
#include <linux/objtool.h>
#include <asm/page.h>
#include <asm/sections.h>

34
tools/arch/x86/include/asm/orc_types.h
View File

@ -39,27 +39,6 @@
#define ORC_REG_SP_INDIRECT 9
#define ORC_REG_MAX 15
/*
* ORC_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP (the
* caller's SP right before it made the call). Used for all callable
* functions, i.e. all C code and all callable asm functions.
*
* ORC_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset points
* to a fully populated pt_regs from a syscall, interrupt, or exception.
*
* ORC_TYPE_REGS_IRET: Used in entry code to indicate that sp_reg+sp_offset
* points to the iret return frame.
*
* The UNWIND_HINT macros are used only for the unwind_hint struct. They
* aren't used in struct orc_entry due to size and complexity constraints.
* Objtool converts them to real types when it converts the hints to orc
* entries.
*/
#define ORC_TYPE_CALL 0
#define ORC_TYPE_REGS 1
#define ORC_TYPE_REGS_IRET 2
#define UNWIND_HINT_TYPE_RET_OFFSET 3
#ifndef __ASSEMBLY__
/*
* This struct is more or less a vastly simplified version of the DWARF Call
@ -78,19 +57,6 @@ struct orc_entry {
unsigned end:1;
} __packed;
/*
* This struct is used by asm and inline asm code to manually annotate the
* location of registers on the stack for the ORC unwinder.
*
* Type can be either ORC_TYPE_* or UNWIND_HINT_TYPE_*.
*/
struct unwind_hint {
u32 ip;
s16 sp_offset;
u8 sp_reg;
u8 type;
u8 end;
};
#endif /* __ASSEMBLY__ */
#endif /* _ORC_TYPES_H */

129
tools/include/linux/objtool.h Normal file
View File

@ -0,0 +1,129 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_OBJTOOL_H
#define _LINUX_OBJTOOL_H
#ifndef __ASSEMBLY__
#include <linux/types.h>
/*
* This struct is used by asm and inline asm code to manually annotate the
* location of registers on the stack.
*/
struct unwind_hint {
u32 ip;
s16 sp_offset;
u8 sp_reg;
u8 type;
u8 end;
};
#endif
/*
* UNWIND_HINT_TYPE_CALL: Indicates that sp_reg+sp_offset resolves to PREV_SP
* (the caller's SP right before it made the call). Used for all callable
* functions, i.e. all C code and all callable asm functions.
*
* UNWIND_HINT_TYPE_REGS: Used in entry code to indicate that sp_reg+sp_offset
* points to a fully populated pt_regs from a syscall, interrupt, or exception.
*
* UNWIND_HINT_TYPE_REGS_PARTIAL: Used in entry code to indicate that
* sp_reg+sp_offset points to the iret return frame.
*/
#define UNWIND_HINT_TYPE_CALL 0
#define UNWIND_HINT_TYPE_REGS 1
#define UNWIND_HINT_TYPE_REGS_PARTIAL 2
#define UNWIND_HINT_TYPE_RET_OFFSET 3
#ifdef CONFIG_STACK_VALIDATION
#ifndef __ASSEMBLY__
#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
"987: \n\t" \
".pushsection .discard.unwind_hints\n\t" \
/* struct unwind_hint */ \
".long 987b - .\n\t" \
".short " __stringify(sp_offset) "\n\t" \
".byte " __stringify(sp_reg) "\n\t" \
".byte " __stringify(type) "\n\t" \
".byte " __stringify(end) "\n\t" \
".balign 4 \n\t" \
".popsection\n\t"
/*
* This macro marks the given function's stack frame as "non-standard", which
* tells objtool to ignore the function when doing stack metadata validation.
* It should only be used in special cases where you're 100% sure it won't
* affect the reliability of frame pointers and kernel stack traces.
*
* For more information, see tools/objtool/Documentation/stack-validation.txt.
*/
#define STACK_FRAME_NON_STANDARD(func) \
static void __used __section(.discard.func_stack_frame_non_standard) \
*__func_stack_frame_non_standard_##func = func
#else /* __ASSEMBLY__ */
/*
* This macro indicates that the following intra-function call is valid.
* Any non-annotated intra-function call will cause objtool to issue a warning.
*/
#define ANNOTATE_INTRA_FUNCTION_CALL \
999: \
.pushsection .discard.intra_function_calls; \
.long 999b; \
.popsection;
/*
* In asm, there are two kinds of code: normal C-type callable functions and
* the rest. The normal callable functions can be called by other code, and
* don't do anything unusual with the stack. Such normal callable functions
* are annotated with the ENTRY/ENDPROC macros. Most asm code falls in this
* category. In this case, no special debugging annotations are needed because
* objtool can automatically generate the ORC data for the ORC unwinder to read
* at runtime.
*
* Anything which doesn't fall into the above category, such as syscall and
* interrupt handlers, tends to not be called directly by other functions, and
* often does unusual non-C-function-type things with the stack pointer. Such
* code needs to be annotated such that objtool can understand it. The
* following CFI hint macros are for this type of code.
*
* These macros provide hints to objtool about the state of the stack at each
* instruction. Objtool starts from the hints and follows the code flow,
* making automatic CFI adjustments when it sees pushes and pops, filling out
* the debuginfo as necessary. It will also warn if it sees any
* inconsistencies.
*/
.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
.Lunwind_hint_ip_\@:
.pushsection .discard.unwind_hints
/* struct unwind_hint */
.long .Lunwind_hint_ip_\@ - .
.short \sp_offset
.byte \sp_reg
.byte \type
.byte \end
.balign 4
.popsection
.endm
#endif /* __ASSEMBLY__ */
#else /* !CONFIG_STACK_VALIDATION */
#ifndef __ASSEMBLY__
#define UNWIND_HINT(sp_reg, sp_offset, type, end) \
"\n\t"
#define STACK_FRAME_NON_STANDARD(func)
#else
#define ANNOTATE_INTRA_FUNCTION_CALL
.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
.endm
#endif
#endif /* CONFIG_STACK_VALIDATION */
#endif /* _LINUX_OBJTOOL_H */

6
tools/objtool/Makefile
View File

@ -37,7 +37,7 @@ INCLUDES := -I$(srctree)/tools/include \
-I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
-I$(srctree)/tools/arch/$(SRCARCH)/include \
-I$(srctree)/tools/objtool/arch/$(SRCARCH)/include
WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed
WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed -Wno-nested-externs
CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
LDFLAGS += $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
@ -55,6 +55,10 @@ ifeq ($(SRCARCH),x86)
SUBCMD_ORC := y
endif
ifeq ($(SUBCMD_ORC),y)
CFLAGS += -DINSN_USE_ORC
endif
export SUBCMD_CHECK SUBCMD_ORC
export srctree OUTPUT CFLAGS SRCARCH AWK
include $(srctree)/tools/build/Makefile.include

4
tools/objtool/arch.h
View File

@ -11,7 +11,9 @@
#include "objtool.h"
#include "cfi.h"
#ifdef INSN_USE_ORC
#include <asm/orc_types.h>
#endif
enum insn_type {
INSN_JUMP_CONDITIONAL,
@ -86,4 +88,6 @@ unsigned long arch_dest_reloc_offset(int addend);
const char *arch_nop_insn(int len);
int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg);
#endif /* _ARCH_H */

1
tools/objtool/arch/x86/Build
View File

@ -1,3 +1,4 @@
objtool-y += special.o
objtool-y += decode.o
inat_tables_script = ../arch/x86/tools/gen-insn-attr-x86.awk

37
tools/objtool/arch/x86/decode.c
View File

@ -15,6 +15,7 @@
#include "../../elf.h"
#include "../../arch.h"
#include "../../warn.h"
#include <asm/orc_types.h>
static unsigned char op_to_cfi_reg[][2] = {
{CFI_AX, CFI_R8},
@ -583,3 +584,39 @@ const char *arch_nop_insn(int len)
return nops[len-1];
}
int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg)
{
struct cfi_reg *cfa = &insn->cfi.cfa;
switch (sp_reg) {
case ORC_REG_UNDEFINED:
cfa->base = CFI_UNDEFINED;
break;
case ORC_REG_SP:
cfa->base = CFI_SP;
break;
case ORC_REG_BP:
cfa->base = CFI_BP;
break;
case ORC_REG_SP_INDIRECT:
cfa->base = CFI_SP_INDIRECT;
break;
case ORC_REG_R10:
cfa->base = CFI_R10;
break;
case ORC_REG_R13:
cfa->base = CFI_R13;
break;
case ORC_REG_DI:
cfa->base = CFI_DI;
break;
case ORC_REG_DX:
cfa->base = CFI_DX;
break;
default:
return -1;
}
return 0;
}

20
tools/objtool/arch/x86/include/arch_special.h Normal file
View File

@ -0,0 +1,20 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _X86_ARCH_SPECIAL_H
#define _X86_ARCH_SPECIAL_H
#define EX_ENTRY_SIZE 12
#define EX_ORIG_OFFSET 0
#define EX_NEW_OFFSET 4
#define JUMP_ENTRY_SIZE 16
#define JUMP_ORIG_OFFSET 0
#define JUMP_NEW_OFFSET 4
#define ALT_ENTRY_SIZE 13
#define ALT_ORIG_OFFSET 0
#define ALT_NEW_OFFSET 4
#define ALT_FEATURE_OFFSET 8
#define ALT_ORIG_LEN_OFFSET 10
#define ALT_NEW_LEN_OFFSET 11
#endif /* _X86_ARCH_SPECIAL_H */

145
tools/objtool/arch/x86/special.c Normal file
View File

@ -0,0 +1,145 @@
// SPDX-License-Identifier: GPL-2.0-or-later
#include <string.h>
#include "../../special.h"
#include "../../builtin.h"
#define X86_FEATURE_POPCNT (4 * 32 + 23)
#define X86_FEATURE_SMAP (9 * 32 + 20)
void arch_handle_alternative(unsigned short feature, struct special_alt *alt)
{
switch (feature) {
case X86_FEATURE_SMAP:
/*
* If UACCESS validation is enabled; force that alternative;
* otherwise force it the other way.
*
* What we want to avoid is having both the original and the
* alternative code flow at the same time, in that case we can
* find paths that see the STAC but take the NOP instead of
* CLAC and the other way around.
*/
if (uaccess)
alt->skip_orig = true;
else
alt->skip_alt = true;
break;
case X86_FEATURE_POPCNT:
/*
* It has been requested that we don't validate the !POPCNT
* feature path which is a "very very small percentage of
* machines".
*/
alt->skip_orig = true;
break;
default:
break;
}
}
bool arch_support_alt_relocation(struct special_alt *special_alt,
struct instruction *insn,
struct reloc *reloc)
{
/*
* The x86 alternatives code adjusts the offsets only when it
* encounters a branch instruction at the very beginning of the
* replacement group.
*/
return insn->offset == special_alt->new_off &&
(insn->type == INSN_CALL || is_static_jump(insn));
}
/*
* There are 3 basic jump table patterns:
*
* 1. jmpq *[rodata addr](,%reg,8)
*
* This is the most common case by far. It jumps to an address in a simple
* jump table which is stored in .rodata.
*
* 2. jmpq *[rodata addr](%rip)
*
* This is caused by a rare GCC quirk, currently only seen in three driver
* functions in the kernel, only with certain obscure non-distro configs.
*
* As part of an optimization, GCC makes a copy of an existing switch jump
* table, modifies it, and then hard-codes the jump (albeit with an indirect
* jump) to use a single entry in the table. The rest of the jump table and
* some of its jump targets remain as dead code.
*
* In such a case we can just crudely ignore all unreachable instruction
* warnings for the entire object file. Ideally we would just ignore them
* for the function, but that would require redesigning the code quite a
* bit. And honestly that's just not worth doing: unreachable instruction
* warnings are of questionable value anyway, and this is such a rare issue.
*
* 3. mov [rodata addr],%reg1
* ... some instructions ...
* jmpq *(%reg1,%reg2,8)
*
* This is a fairly uncommon pattern which is new for GCC 6. As of this
* writing, there are 11 occurrences of it in the allmodconfig kernel.
*
* As of GCC 7 there are quite a few more of these and the 'in between' code
* is significant. Esp. with KASAN enabled some of the code between the mov
* and jmpq uses .rodata itself, which can confuse things.
*
* TODO: Once we have DWARF CFI and smarter instruction decoding logic,
* ensure the same register is used in the mov and jump instructions.
*
* NOTE: RETPOLINE made it harder still to decode dynamic jumps.
*/
struct reloc *arch_find_switch_table(struct objtool_file *file,
struct instruction *insn)
{
struct reloc *text_reloc, *rodata_reloc;
struct section *table_sec;
unsigned long table_offset;
/* look for a relocation which references .rodata */
text_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
insn->offset, insn->len);
if (!text_reloc || text_reloc->sym->type != STT_SECTION ||
!text_reloc->sym->sec->rodata)
return NULL;
table_offset = text_reloc->addend;
table_sec = text_reloc->sym->sec;
if (text_reloc->type == R_X86_64_PC32)
table_offset += 4;
/*
* Make sure the .rodata address isn't associated with a
* symbol. GCC jump tables are anonymous data.
*
* Also support C jump tables which are in the same format as
* switch jump tables. For objtool to recognize them, they
* need to be placed in the C_JUMP_TABLE_SECTION section. They
* have symbols associated with them.
*/
if (find_symbol_containing(table_sec, table_offset) &&
strcmp(table_sec->name, C_JUMP_TABLE_SECTION))
return NULL;
/*
* Each table entry has a rela associated with it. The rela
* should reference text in the same function as the original
* instruction.
*/
rodata_reloc = find_reloc_by_dest(file->elf, table_sec, table_offset);
if (!rodata_reloc)
return NULL;
/*
* Use of RIP-relative switch jumps is quite rare, and
* indicates a rare GCC quirk/bug which can leave dead
* code behind.
*/
if (text_reloc->type == R_X86_64_PC32)
file->ignore_unreachables = true;
return rodata_reloc;
}

15
tools/objtool/builtin-check.c
View File

@ -41,6 +41,8 @@ const struct option check_options[] = {
int cmd_check(int argc, const char **argv)
{
const char *objname, *s;
struct objtool_file *file;
int ret;
argc = parse_options(argc, argv, check_options, check_usage, 0);
@ -53,5 +55,16 @@ int cmd_check(int argc, const char **argv)
if (s && !s[9])
vmlinux = true;
return check(objname, false);
file = objtool_open_read(objname);
if (!file)
return 1;
ret = check(file);
if (ret)
return ret;
if (file->elf->changed)
return elf_write(file->elf);
return 0;
}

27
tools/objtool/builtin-orc.c
View File

@ -31,13 +31,38 @@ int cmd_orc(int argc, const char **argv)
usage_with_options(orc_usage, check_options);
if (!strncmp(argv[0], "gen", 3)) {
struct objtool_file *file;
int ret;
argc = parse_options(argc, argv, check_options, orc_usage, 0);
if (argc != 1)
usage_with_options(orc_usage, check_options);
objname = argv[0];
return check(objname, true);
file = objtool_open_read(objname);
if (!file)
return 1;
ret = check(file);
if (ret)
return ret;
if (list_empty(&file->insn_list))
return 0;
ret = create_orc(file);
if (ret)
return ret;
ret = create_orc_sections(file);
if (ret)
return ret;
if (!file->elf->changed)
return 0;
return elf_write(file->elf);
}
if (!strcmp(argv[0], "dump")) {

230
tools/objtool/check.c
View File

@ -14,21 +14,19 @@
#include "warn.h"
#include "arch_elf.h"
#include <linux/objtool.h>
#include <linux/hashtable.h>
#include <linux/kernel.h>
#include <linux/static_call_types.h>
#define FAKE_JUMP_OFFSET -1
#define C_JUMP_TABLE_SECTION ".rodata..c_jump_table"
struct alternative {
struct list_head list;
struct instruction *insn;
bool skip_orig;
};
const char *objname;
struct cfi_init_state initial_func_cfi;
struct instruction *find_insn(struct objtool_file *file,
@ -111,12 +109,6 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
for (insn = next_insn_same_sec(file, insn); insn; \
insn = next_insn_same_sec(file, insn))
static bool is_static_jump(struct instruction *insn)
{
return insn->type == INSN_JUMP_CONDITIONAL ||
insn->type == INSN_JUMP_UNCONDITIONAL;
}
static bool is_sibling_call(struct instruction *insn)
{
/* An indirect jump is either a sibling call or a jump to a table. */
@ -591,6 +583,8 @@ static const char *uaccess_safe_builtin[] = {
"__asan_store4_noabort",
"__asan_store8_noabort",
"__asan_store16_noabort",
"__kasan_check_read",
"__kasan_check_write",
/* KASAN in-line */
"__asan_report_load_n_noabort",
"__asan_report_load1_noabort",
@ -879,6 +873,17 @@ static void remove_insn_ops(struct instruction *insn)
}
}
static struct symbol *find_call_destination(struct section *sec, unsigned long offset)
{
struct symbol *call_dest;
call_dest = find_func_by_offset(sec, offset);
if (!call_dest)
call_dest = find_symbol_by_offset(sec, offset);
return call_dest;
}
/*
* Find the destination instructions for all calls.
*/
@ -896,9 +901,7 @@ static int add_call_destinations(struct objtool_file *file)
insn->offset, insn->len);
if (!reloc) {
dest_off = arch_jump_destination(insn);
insn->call_dest = find_func_by_offset(insn->sec, dest_off);
if (!insn->call_dest)
insn->call_dest = find_symbol_by_offset(insn->sec, dest_off);
insn->call_dest = find_call_destination(insn->sec, dest_off);
if (insn->ignore)
continue;
@ -916,8 +919,8 @@ static int add_call_destinations(struct objtool_file *file)
} else if (reloc->sym->type == STT_SECTION) {
dest_off = arch_dest_reloc_offset(reloc->addend);
insn->call_dest = find_func_by_offset(reloc->sym->sec,
dest_off);
insn->call_dest = find_call_destination(reloc->sym->sec,
dest_off);
if (!insn->call_dest) {
WARN_FUNC("can't find call dest symbol at %s+0x%lx",
insn->sec, insn->offset,
@ -1029,6 +1032,8 @@ static int handle_group_alt(struct objtool_file *file,
alt_group = alt_group_next_index++;
insn = *new_insn;
sec_for_each_insn_from(file, insn) {
struct reloc *alt_reloc;
if (insn->offset >= special_alt->new_off + special_alt->new_len)
break;
@ -1045,14 +1050,11 @@ static int handle_group_alt(struct objtool_file *file,
* .altinstr_replacement section, unless the arch's
* alternatives code can adjust the relative offsets
* accordingly.
*
* The x86 alternatives code adjusts the offsets only when it
* encounters a branch instruction at the very beginning of the
* replacement group.
*/
if ((insn->offset != special_alt->new_off ||
(insn->type != INSN_CALL && !is_static_jump(insn))) &&
find_reloc_by_dest_range(file->elf, insn->sec, insn->offset, insn->len)) {
alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
insn->offset, insn->len);
if (alt_reloc &&
!arch_support_alt_relocation(special_alt, insn, alt_reloc)) {
WARN_FUNC("unsupported relocation in alternatives section",
insn->sec, insn->offset);
@ -1254,56 +1256,15 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
}
/*
* find_jump_table() - Given a dynamic jump, find the switch jump table in
* .rodata associated with it.
*
* There are 3 basic patterns:
*
* 1. jmpq *[rodata addr](,%reg,8)
*
* This is the most common case by far. It jumps to an address in a simple
* jump table which is stored in .rodata.
*
* 2. jmpq *[rodata addr](%rip)
*
* This is caused by a rare GCC quirk, currently only seen in three driver
* functions in the kernel, only with certain obscure non-distro configs.
*
* As part of an optimization, GCC makes a copy of an existing switch jump
* table, modifies it, and then hard-codes the jump (albeit with an indirect
* jump) to use a single entry in the table. The rest of the jump table and
* some of its jump targets remain as dead code.
*
* In such a case we can just crudely ignore all unreachable instruction
* warnings for the entire object file. Ideally we would just ignore them
* for the function, but that would require redesigning the code quite a
* bit. And honestly that's just not worth doing: unreachable instruction
* warnings are of questionable value anyway, and this is such a rare issue.
*
* 3. mov [rodata addr],%reg1
* ... some instructions ...
* jmpq *(%reg1,%reg2,8)
*
* This is a fairly uncommon pattern which is new for GCC 6. As of this
* writing, there are 11 occurrences of it in the allmodconfig kernel.
*
* As of GCC 7 there are quite a few more of these and the 'in between' code
* is significant. Esp. with KASAN enabled some of the code between the mov
* and jmpq uses .rodata itself, which can confuse things.
*
* TODO: Once we have DWARF CFI and smarter instruction decoding logic,
* ensure the same register is used in the mov and jump instructions.
*
* NOTE: RETPOLINE made it harder still to decode dynamic jumps.
* find_jump_table() - Given a dynamic jump, find the switch jump table
* associated with it.
*/
static struct reloc *find_jump_table(struct objtool_file *file,
struct symbol *func,
struct instruction *insn)
{
struct reloc *text_reloc, *table_reloc;
struct reloc *table_reloc;
struct instruction *dest_insn, *orig_insn = insn;
struct section *table_sec;
unsigned long table_offset;
/*
* Backward search using the @first_jump_src links, these help avoid
@ -1324,52 +1285,13 @@ static struct reloc *find_jump_table(struct objtool_file *file,
insn->jump_dest->offset > orig_insn->offset))
break;
/* look for a relocation which references .rodata */
text_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
insn->offset, insn->len);
if (!text_reloc || text_reloc->sym->type != STT_SECTION ||
!text_reloc->sym->sec->rodata)
continue;
table_offset = text_reloc->addend;
table_sec = text_reloc->sym->sec;
if (text_reloc->type == R_X86_64_PC32)
table_offset += 4;
/*
* Make sure the .rodata address isn't associated with a
* symbol. GCC jump tables are anonymous data.
*
* Also support C jump tables which are in the same format as
* switch jump tables. For objtool to recognize them, they
* need to be placed in the C_JUMP_TABLE_SECTION section. They
* have symbols associated with them.
*/
if (find_symbol_containing(table_sec, table_offset) &&
strcmp(table_sec->name, C_JUMP_TABLE_SECTION))
continue;
/*
* Each table entry has a reloc associated with it. The reloc
* should reference text in the same function as the original
* instruction.
*/
table_reloc = find_reloc_by_dest(file->elf, table_sec, table_offset);
table_reloc = arch_find_switch_table(file, insn);
if (!table_reloc)
continue;
dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);
if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)
continue;
/*
* Use of RIP-relative switch jumps is quite rare, and
* indicates a rare GCC quirk/bug which can leave dead code
* behind.
*/
if (text_reloc->type == R_X86_64_PC32)
file->ignore_unreachables = true;
return table_reloc;
}
@ -1512,32 +1434,7 @@ static int read_unwind_hints(struct objtool_file *file)
insn->hint = true;
switch (hint->sp_reg) {
case ORC_REG_UNDEFINED:
cfa->base = CFI_UNDEFINED;
break;
case ORC_REG_SP:
cfa->base = CFI_SP;
break;
case ORC_REG_BP:
cfa->base = CFI_BP;
break;
case ORC_REG_SP_INDIRECT:
cfa->base = CFI_SP_INDIRECT;
break;
case ORC_REG_R10:
cfa->base = CFI_R10;
break;
case ORC_REG_R13:
cfa->base = CFI_R13;
break;
case ORC_REG_DI:
cfa->base = CFI_DI;
break;
case ORC_REG_DX:
cfa->base = CFI_DX;
break;
default:
if (arch_decode_hint_reg(insn, hint->sp_reg)) {
WARN_FUNC("unsupported unwind_hint sp base reg %d",
insn->sec, insn->offset, hint->sp_reg);
return -1;
@ -1951,7 +1848,8 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
return 0;
}
if (cfi->type == ORC_TYPE_REGS || cfi->type == ORC_TYPE_REGS_IRET)
if (cfi->type == UNWIND_HINT_TYPE_REGS ||
cfi->type == UNWIND_HINT_TYPE_REGS_PARTIAL)
return update_cfi_state_regs(insn, cfi, op);
switch (op->dest.type) {
@ -2199,7 +2097,7 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
/* drap: push %rbp */
cfi->stack_size = 0;
} else if (regs[op->src.reg].base == CFI_UNDEFINED) {
} else {
/* drap: push %reg */
save_reg(cfi, op->src.reg, CFI_BP, -cfi->stack_size);
@ -2228,9 +2126,7 @@ static int update_cfi_state(struct instruction *insn, struct cfi_state *cfi,
/* save drap offset so we know when to restore it */
cfi->drap_offset = op->dest.offset;
}
else if (regs[op->src.reg].base == CFI_UNDEFINED) {
} else {
/* drap: mov reg, disp(%rbp) */
save_reg(cfi, op->src.reg, CFI_BP, op->dest.offset);
@ -2800,9 +2696,10 @@ static bool is_ubsan_insn(struct instruction *insn)
"__ubsan_handle_builtin_unreachable"));
}
static bool ignore_unreachable_insn(struct instruction *insn)
static bool ignore_unreachable_insn(struct objtool_file *file, struct instruction *insn)
{
int i;
struct instruction *prev_insn;
if (insn->ignore || insn->type == INSN_NOP)
return true;
@ -2819,6 +2716,9 @@ static bool ignore_unreachable_insn(struct instruction *insn)
!strcmp(insn->sec->name, ".altinstr_aux"))
return true;
if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->offset == FAKE_JUMP_OFFSET)
return true;
if (!insn->func)
return false;
@ -2827,8 +2727,11 @@ static bool ignore_unreachable_insn(struct instruction *insn)
* __builtin_unreachable(). The BUG() macro has an unreachable() after
* the UD2, which causes GCC's undefined trap logic to emit another UD2
* (or occasionally a JMP to UD2).
*
* It may also insert a UD2 after calling a __noreturn function.
*/
if (list_prev_entry(insn, list)->dead_end &&
prev_insn = list_prev_entry(insn, list);
if ((prev_insn->dead_end || dead_end_function(file, prev_insn->call_dest)) &&
(insn->type == INSN_BUG ||
(insn->type == INSN_JUMP_UNCONDITIONAL &&
insn->jump_dest && insn->jump_dest->type == INSN_BUG)))
@ -2955,7 +2858,7 @@ static int validate_reachable_instructions(struct objtool_file *file)
return 0;
for_each_insn(file, insn) {
if (insn->visited || ignore_unreachable_insn(insn))
if (insn->visited || ignore_unreachable_insn(file, insn))
continue;
WARN_FUNC("unreachable instruction", insn->sec, insn->offset);
@ -2965,37 +2868,22 @@ static int validate_reachable_instructions(struct objtool_file *file)
return 0;
}
static struct objtool_file file;
int check(const char *_objname, bool orc)
int check(struct objtool_file *file)
{
int ret, warnings = 0;
objname = _objname;
file.elf = elf_open_read(objname, O_RDWR);
if (!file.elf)
return 1;
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
INIT_LIST_HEAD(&file.static_call_list);
file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;
arch_initial_func_cfi_state(&initial_func_cfi);
ret = decode_sections(&file);
ret = decode_sections(file);
if (ret < 0)
goto out;
warnings += ret;
if (list_empty(&file.insn_list))
if (list_empty(&file->insn_list))
goto out;
if (vmlinux && !validate_dup) {
ret = validate_vmlinux_functions(&file);
ret = validate_vmlinux_functions(file);
if (ret < 0)
goto out;
@ -3004,50 +2892,34 @@ int check(const char *_objname, bool orc)
}
if (retpoline) {
ret = validate_retpoline(&file);
ret = validate_retpoline(file);
if (ret < 0)
return ret;
warnings += ret;
}
ret = validate_functions(&file);
ret = validate_functions(file);
if (ret < 0)
goto out;
warnings += ret;
ret = validate_unwind_hints(&file, NULL);
ret = validate_unwind_hints(file, NULL);
if (ret < 0)
goto out;
warnings += ret;
if (!warnings) {
ret = validate_reachable_instructions(&file);
ret = validate_reachable_instructions(file);
if (ret < 0)
goto out;
warnings += ret;
}
ret = create_static_call_sections(&file);
ret = create_static_call_sections(file);
if (ret < 0)
goto out;
warnings += ret;
if (orc) {
ret = create_orc(&file);
if (ret < 0)
goto out;
ret = create_orc_sections(&file);
if (ret < 0)
goto out;
}
if (file.elf->changed) {
ret = elf_write(file.elf);
if (ret < 0)
goto out;
}
out:
if (ret < 0) {
/*

9
tools/objtool/check.h
View File

@ -43,9 +43,17 @@ struct instruction {
struct symbol *func;
struct list_head stack_ops;
struct cfi_state cfi;
#ifdef INSN_USE_ORC
struct orc_entry orc;
#endif
};
static inline bool is_static_jump(struct instruction *insn)
{
return insn->type == INSN_JUMP_CONDITIONAL ||
insn->type == INSN_JUMP_UNCONDITIONAL;
}
struct instruction *find_insn(struct objtool_file *file,
struct section *sec, unsigned long offset);
@ -58,5 +66,4 @@ struct instruction *find_insn(struct objtool_file *file,
insn->sec == sec; \
insn = list_next_entry(insn, list))
#endif /* _CHECK_H */

30
tools/objtool/objtool.c
View File

@ -22,6 +22,8 @@
#include <linux/kernel.h>
#include "builtin.h"
#include "objtool.h"
#include "warn.h"
struct cmd_struct {
const char *name;
@ -39,6 +41,34 @@ static struct cmd_struct objtool_cmds[] = {
bool help;
const char *objname;
static struct objtool_file file;
struct objtool_file *objtool_open_read(const char *_objname)
{
if (objname) {
if (strcmp(objname, _objname)) {
WARN("won't handle more than one file at a time");
return NULL;
}
return &file;
}
objname = _objname;
file.elf = elf_open_read(objname, O_RDWR);
if (!file.elf)
return NULL;
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
INIT_LIST_HEAD(&file.static_call_list);
file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;
return &file;
}
static void cmd_usage(void)
{
unsigned int i, longest = 0;

6
tools/objtool/objtool.h
View File

@ -12,6 +12,8 @@
#include "elf.h"
#define __weak __attribute__((weak))
struct objtool_file {
struct elf *elf;
struct list_head insn_list;
@ -20,7 +22,9 @@ struct objtool_file {
bool ignore_unreachables, c_file, hints, rodata;
};
int check(const char *objname, bool orc);
struct objtool_file *objtool_open_read(const char *_objname);
int check(struct objtool_file *file);
int orc_dump(const char *objname);
int create_orc(struct objtool_file *file);
int create_orc_sections(struct objtool_file *file);

9
tools/objtool/orc_dump.c
View File

@ -4,6 +4,7 @@
*/
#include <unistd.h>
#include <linux/objtool.h>
#include <asm/orc_types.h>
#include "objtool.h"
#include "warn.h"
@ -37,12 +38,12 @@ static const char *reg_name(unsigned int reg)
static const char *orc_type_name(unsigned int type)
{
switch (type) {
case ORC_TYPE_CALL:
case UNWIND_HINT_TYPE_CALL:
return "call";
case ORC_TYPE_REGS:
case UNWIND_HINT_TYPE_REGS:
return "regs";
case ORC_TYPE_REGS_IRET:
return "iret";
case UNWIND_HINT_TYPE_REGS_PARTIAL:
return "regs (partial)";
default:
return "?";
}

8
tools/objtool/orc_gen.c
View File

@ -6,6 +6,9 @@
#include <stdlib.h>
#include <string.h>
#include <linux/objtool.h>
#include <asm/orc_types.h>
#include "check.h"
#include "warn.h"
@ -18,6 +21,9 @@ int create_orc(struct objtool_file *file)
struct cfi_reg *cfa = &insn->cfi.cfa;
struct cfi_reg *bp = &insn->cfi.regs[CFI_BP];
if (!insn->sec->text)
continue;
orc->end = insn->cfi.end;
if (cfa->base == CFI_UNDEFINED) {
@ -143,7 +149,7 @@ int create_orc_sections(struct objtool_file *file)
struct orc_entry empty = {
.sp_reg = ORC_REG_UNDEFINED,
.bp_reg = ORC_REG_UNDEFINED,
.type = ORC_TYPE_CALL,
.type = UNWIND_HINT_TYPE_CALL,
};
sec = find_section_by_name(file->elf, ".orc_unwind");

48
tools/objtool/special.c
View File

@ -14,24 +14,7 @@
#include "builtin.h"
#include "special.h"
#include "warn.h"
#define EX_ENTRY_SIZE 12
#define EX_ORIG_OFFSET 0
#define EX_NEW_OFFSET 4
#define JUMP_ENTRY_SIZE 16
#define JUMP_ORIG_OFFSET 0
#define JUMP_NEW_OFFSET 4
#define ALT_ENTRY_SIZE 13
#define ALT_ORIG_OFFSET 0
#define ALT_NEW_OFFSET 4
#define ALT_FEATURE_OFFSET 8
#define ALT_ORIG_LEN_OFFSET 10
#define ALT_NEW_LEN_OFFSET 11
#define X86_FEATURE_POPCNT (4*32+23)
#define X86_FEATURE_SMAP (9*32+20)
#include "arch_special.h"
struct special_entry {
const char *sec;
@ -68,6 +51,10 @@ struct special_entry entries[] = {
{},
};
void __weak arch_handle_alternative(unsigned short feature, struct special_alt *alt)
{
}
static int get_alt_entry(struct elf *elf, struct special_entry *entry,
struct section *sec, int idx,
struct special_alt *alt)
@ -92,30 +79,7 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
feature = *(unsigned short *)(sec->data->d_buf + offset +
entry->feature);
/*
* It has been requested that we don't validate the !POPCNT
* feature path which is a "very very small percentage of
* machines".
*/
if (feature == X86_FEATURE_POPCNT)
alt->skip_orig = true;
/*
* If UACCESS validation is enabled; force that alternative;
* otherwise force it the other way.
*
* What we want to avoid is having both the original and the
* alternative code flow at the same time, in that case we can
* find paths that see the STAC but take the NOP instead of
* CLAC and the other way around.
*/
if (feature == X86_FEATURE_SMAP) {
if (uaccess)
alt->skip_orig = true;
else
alt->skip_alt = true;
}
arch_handle_alternative(feature, alt);
}
orig_reloc = find_reloc_by_dest(elf, sec, offset + entry->orig);

10
tools/objtool/special.h
View File

@ -7,8 +7,11 @@
#define _SPECIAL_H
#include <stdbool.h>
#include "check.h"
#include "elf.h"
#define C_JUMP_TABLE_SECTION ".rodata..c_jump_table"
struct special_alt {
struct list_head list;
@ -28,4 +31,11 @@ struct special_alt {
int special_get_alts(struct elf *elf, struct list_head *alts);
void arch_handle_alternative(unsigned short feature, struct special_alt *alt);
bool arch_support_alt_relocation(struct special_alt *special_alt,
struct instruction *insn,
struct reloc *reloc);
struct reloc *arch_find_switch_table(struct objtool_file *file,
struct instruction *insn);
#endif /* _SPECIAL_H */

32
tools/objtool/sync-check.sh
View File

@ -1,14 +1,27 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
FILES='
if [ -z "$SRCARCH" ]; then
echo 'sync-check.sh: error: missing $SRCARCH environment variable' >&2
exit 1
fi
FILES="include/linux/objtool.h"
if [ "$SRCARCH" = "x86" ]; then
FILES="$FILES
arch/x86/include/asm/inat_types.h
arch/x86/include/asm/orc_types.h
arch/x86/include/asm/emulate_prefix.h
arch/x86/lib/x86-opcode-map.txt
arch/x86/tools/gen-insn-attr-x86.awk
include/linux/static_call_types.h
'
arch/x86/include/asm/inat.h -I '^#include [\"<]\(asm/\)*inat_types.h[\">]'
arch/x86/include/asm/insn.h -I '^#include [\"<]\(asm/\)*inat.h[\">]'
arch/x86/lib/inat.c -I '^#include [\"<]\(../include/\)*asm/insn.h[\">]'
arch/x86/lib/insn.c -I '^#include [\"<]\(../include/\)*asm/in\(at\|sn\).h[\">]' -I '^#include [\"<]\(../include/\)*asm/emulate_prefix.h[\">]'
"
fi
check_2 () {
file1=$1
@ -41,11 +54,12 @@ fi
cd ../..
for i in $FILES; do
check $i
done
while read -r file_entry; do
if [ -z "$file_entry" ]; then
continue
fi
check arch/x86/include/asm/inat.h '-I "^#include [\"<]\(asm/\)*inat_types.h[\">]"'
check arch/x86/include/asm/insn.h '-I "^#include [\"<]\(asm/\)*inat.h[\">]"'
check arch/x86/lib/inat.c '-I "^#include [\"<]\(../include/\)*asm/insn.h[\">]"'
check arch/x86/lib/insn.c '-I "^#include [\"<]\(../include/\)*asm/in\(at\|sn\).h[\">]" -I "^#include [\"<]\(../include/\)*asm/emulate_prefix.h[\">]"'
check $file_entry
done <<EOF
$FILES
EOF

6
tools/objtool/weak.c
View File

@ -9,17 +9,13 @@
#include <errno.h>
#include "objtool.h"
#define __weak __attribute__((weak))
#define UNSUPPORTED(name) \
({ \
fprintf(stderr, "error: objtool: " name " not implemented\n"); \
return ENOSYS; \
})
const char __weak *objname;
int __weak check(const char *_objname, bool orc)
int __weak check(struct objtool_file *file)
{
UNSUPPORTED("check subcommand");
}

2
tools/perf/Makefile.config
View File

@ -16,7 +16,7 @@ $(shell printf "" > $(OUTPUT).config-detected)
detected = $(shell echo "$(1)=y" >> $(OUTPUT).config-detected)
detected_var = $(shell echo "$(1)=$($(1))" >> $(OUTPUT).config-detected)
CFLAGS := $(EXTRA_CFLAGS) $(EXTRA_WARNINGS)
CFLAGS := $(EXTRA_CFLAGS) $(filter-out -Wnested-externs,$(EXTRA_WARNINGS))
include $(srctree)/tools/scripts/Makefile.arch