[PATCH v2 8/9] frame: Make unwind hints definitions available to other architectures

From: Julien Thierry
Date: Thu Jul 30 2020 - 05:47:30 EST

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Next in thread: Josh Poimboeuf: "Re: [PATCH v2 8/9] frame: Make unwind hints definitions available to other architectures"
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Unwind hints are useful to provide objtool with information about stack
states in non-standard functions/code.
While the type of information being provided might be very arch
specific, the mechanism to provide the information can be useful for
other architectures.

Move the relevant unwint hint definitions for all architectures to
see.

Signed-off-by: Julien Thierry <jthierry@xxxxxxxxxx>
---
arch/x86/include/asm/orc_types.h | 13 ---
arch/x86/include/asm/unwind_hints.h | 44 ++--------
include/linux/frame.h | 72 ++++++++++++++++
tools/arch/x86/include/asm/orc_types.h | 13 ---
tools/include/linux/frame.h | 113 +++++++++++++++++++++++++
tools/objtool/check.c | 1 +
tools/objtool/sync-check.sh | 4 +-
7 files changed, 194 insertions(+), 66 deletions(-)
create mode 100644 tools/include/linux/frame.h

diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h
index d25534940bde..00408d30b13e 100644
--- a/arch/x86/include/asm/orc_types.h
+++ b/arch/x86/include/asm/orc_types.h
@@ -78,19 +78,6 @@ 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 */
diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 7d903fdb3f43..e81a18bb114f 100644
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -1,48 +1,14 @@
#ifndef _ASM_X86_UNWIND_HINTS_H
#define _ASM_X86_UNWIND_HINTS_H

+#include <linux/frame.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=ORC_TYPE_CALL end=1
.endm

.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 iret=0
@@ -83,7 +49,7 @@
.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=ORC_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__ */
diff --git a/include/linux/frame.h b/include/linux/frame.h
index d946adb5de17..fa06f2b99625 100644
--- a/include/linux/frame.h
+++ b/include/linux/frame.h
@@ -2,9 +2,39 @@
#ifndef _LINUX_FRAME_H
#define _LINUX_FRAME_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
+
#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.
@@ -29,12 +59,54 @@
.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 */

diff --git a/tools/arch/x86/include/asm/orc_types.h b/tools/arch/x86/include/asm/orc_types.h
index d25534940bde..00408d30b13e 100644
--- a/tools/arch/x86/include/asm/orc_types.h
+++ b/tools/arch/x86/include/asm/orc_types.h
@@ -78,19 +78,6 @@ 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 */
diff --git a/tools/include/linux/frame.h b/tools/include/linux/frame.h
new file mode 100644
index 000000000000..fa06f2b99625
--- /dev/null
+++ b/tools/include/linux/frame.h
@@ -0,0 +1,113 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_FRAME_H
+#define _LINUX_FRAME_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
+
+#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_FRAME_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 60f5be2accf6..d6731e88259d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -14,6 +14,7 @@
#include "warn.h"
#include "arch_elf.h"

+#include <linux/frame.h>
#include <linux/hashtable.h>
#include <linux/kernel.h>

diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
index f01b5a4d12ac..dc14ade100aa 100755
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -3,8 +3,10 @@

TARGET_ARCH=$1

+FILES="include/linux/frame.h"
+
if [ "$TARGET_ARCH" == "x86" ]; then
-FILES="
+FILES="$FILES
arch/x86/include/asm/inat_types.h
arch/x86/include/asm/orc_types.h
arch/x86/include/asm/emulate_prefix.h
--
2.21.3

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