x86/unwind/orc: Add 'signal' field to ORC metadata

Add a 'signal' field which allows unwind hints to specify whether the
instruction pointer should be taken literally (like for most interrupts
and exceptions) rather than decremented (like for call stack return
addresses) when used to find the next ORC entry.
Signed-off-by: NJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/d2c5ec4d83a45b513d8fd72fab59f1a8cfa46871.1676068346.git.jpoimboe@kernel.org

arch/x86/include/asm/orc_types.h

@@ -57,12 +57,14 @@ struct orc_entry {
 	unsigned	sp_reg:4;
 	unsigned	bp_reg:4;
 	unsigned	type:2;
+	unsigned	signal:1;
 	unsigned	end:1;
 #elif defined(__BIG_ENDIAN_BITFIELD)
 	unsigned	bp_reg:4;
 	unsigned	sp_reg:4;
-	unsigned	unused:5;
+	unsigned	unused:4;
 	unsigned	end:1;
+	unsigned	signal:1;
 	unsigned	type:2;
 #endif
 } __packed;

arch/x86/include/asm/unwind_hints.h

@@ -15,7 +15,7 @@
 	UNWIND_HINT type=UNWIND_HINT_TYPE_ENTRY end=1
 .endm
 
-.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 partial=0
+.macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 partial=0 signal=1
 	.if \base == %rsp
 		.if \indirect
 			.set sp_reg, ORC_REG_SP_INDIRECT
@@ -45,11 +45,11 @@
 		.set type, UNWIND_HINT_TYPE_REGS
 	.endif
 
-	UNWIND_HINT sp_reg=sp_reg sp_offset=sp_offset type=type
+	UNWIND_HINT sp_reg=sp_reg sp_offset=sp_offset type=type signal=\signal
 .endm
 
-.macro UNWIND_HINT_IRET_REGS base=%rsp offset=0
-	UNWIND_HINT_REGS base=\base offset=\offset partial=1
+.macro UNWIND_HINT_IRET_REGS base=%rsp offset=0 signal=1
+	UNWIND_HINT_REGS base=\base offset=\offset partial=1 signal=\signal
 .endm
 
 .macro UNWIND_HINT_FUNC
@@ -67,7 +67,7 @@
 #else
 
 #define UNWIND_HINT_FUNC \
-	UNWIND_HINT(ORC_REG_SP, 8, UNWIND_HINT_TYPE_FUNC, 0)
+	UNWIND_HINT(ORC_REG_SP, 8, UNWIND_HINT_TYPE_FUNC, 0, 0)
 
 #endif /* __ASSEMBLY__ */
 

arch/x86/kernel/unwind_orc.c

@@ -484,6 +484,8 @@ bool unwind_next_frame(struct unwind_state *state)
 		goto the_end;
 	}
 
+	state->signal = orc->signal;
+
 	/* Find the previous frame's stack: */
 	switch (orc->sp_reg) {
 	case ORC_REG_SP:
@@ -563,7 +565,6 @@ bool unwind_next_frame(struct unwind_state *state)
 		state->sp = sp;
 		state->regs = NULL;
 		state->prev_regs = NULL;
-		state->signal = false;
 		break;
 
 	case UNWIND_HINT_TYPE_REGS:
@@ -587,7 +588,6 @@ bool unwind_next_frame(struct unwind_state *state)
 		state->regs = (struct pt_regs *)sp;
 		state->prev_regs = NULL;
 		state->full_regs = true;
-		state->signal = true;
 		break;
 
 	case UNWIND_HINT_TYPE_REGS_PARTIAL:
@@ -604,7 +604,6 @@ bool unwind_next_frame(struct unwind_state *state)
 			state->prev_regs = state->regs;
 		state->regs = (void *)sp - IRET_FRAME_OFFSET;
 		state->full_regs = false;
-		state->signal = true;
 		break;
 
 	default:

include/linux/objtool.h

@@ -15,6 +15,7 @@ struct unwind_hint {
 	s16		sp_offset;
 	u8		sp_reg;
 	u8		type;
+	u8		signal;
 	u8		end;
 };
 #endif
@@ -49,7 +50,7 @@ struct unwind_hint {
 
 #ifndef __ASSEMBLY__
 
-#define UNWIND_HINT(sp_reg, sp_offset, type, end)		\
+#define UNWIND_HINT(sp_reg, sp_offset, type, signal, end)	\
 	"987: \n\t"						\
 	".pushsection .discard.unwind_hints\n\t"		\
 	/* struct unwind_hint */				\
@@ -57,6 +58,7 @@ struct unwind_hint {
 	".short " __stringify(sp_offset) "\n\t"			\
 	".byte " __stringify(sp_reg) "\n\t"			\
 	".byte " __stringify(type) "\n\t"			\
+	".byte " __stringify(signal) "\n\t"			\
 	".byte " __stringify(end) "\n\t"			\
 	".balign 4 \n\t"					\
 	".popsection\n\t"
@@ -129,7 +131,7 @@ struct unwind_hint {
  * the debuginfo as necessary.  It will also warn if it sees any
  * inconsistencies.
  */
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
 .Lunwind_hint_ip_\@:
 	.pushsection .discard.unwind_hints
 		/* struct unwind_hint */
@@ -137,6 +139,7 @@ struct unwind_hint {
 		.short \sp_offset
 		.byte \sp_reg
 		.byte \type
+		.byte \signal
 		.byte \end
 		.balign 4
 	.popsection
@@ -174,7 +177,7 @@ struct unwind_hint {
 
 #ifndef __ASSEMBLY__
 
-#define UNWIND_HINT(sp_reg, sp_offset, type, end)	\
+#define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \
 	"\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
 #define STACK_FRAME_NON_STANDARD_FP(func)
@@ -182,7 +185,7 @@ struct unwind_hint {
 #define ASM_REACHABLE
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
 .endm
 .macro STACK_FRAME_NON_STANDARD func:req
 .endm

tools/arch/x86/include/asm/orc_types.h

@@ -57,12 +57,14 @@ struct orc_entry {
 	unsigned	sp_reg:4;
 	unsigned	bp_reg:4;
 	unsigned	type:2;
+	unsigned	signal:1;
 	unsigned	end:1;
 #elif defined(__BIG_ENDIAN_BITFIELD)
 	unsigned	bp_reg:4;
 	unsigned	sp_reg:4;
-	unsigned	unused:5;
+	unsigned	unused:4;
 	unsigned	end:1;
+	unsigned	signal:1;
 	unsigned	type:2;
 #endif
 } __packed;

tools/include/linux/objtool.h

@@ -15,6 +15,7 @@ struct unwind_hint {
 	s16		sp_offset;
 	u8		sp_reg;
 	u8		type;
+	u8		signal;
 	u8		end;
 };
 #endif
@@ -49,7 +50,7 @@ struct unwind_hint {
 
 #ifndef __ASSEMBLY__
 
-#define UNWIND_HINT(sp_reg, sp_offset, type, end)		\
+#define UNWIND_HINT(sp_reg, sp_offset, type, signal, end)	\
 	"987: \n\t"						\
 	".pushsection .discard.unwind_hints\n\t"		\
 	/* struct unwind_hint */				\
@@ -57,6 +58,7 @@ struct unwind_hint {
 	".short " __stringify(sp_offset) "\n\t"			\
 	".byte " __stringify(sp_reg) "\n\t"			\
 	".byte " __stringify(type) "\n\t"			\
+	".byte " __stringify(signal) "\n\t"			\
 	".byte " __stringify(end) "\n\t"			\
 	".balign 4 \n\t"					\
 	".popsection\n\t"
@@ -129,7 +131,7 @@ struct unwind_hint {
  * the debuginfo as necessary.  It will also warn if it sees any
  * inconsistencies.
  */
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
 .Lunwind_hint_ip_\@:
 	.pushsection .discard.unwind_hints
 		/* struct unwind_hint */
@@ -137,6 +139,7 @@ struct unwind_hint {
 		.short \sp_offset
 		.byte \sp_reg
 		.byte \type
+		.byte \signal
 		.byte \end
 		.balign 4
 	.popsection
@@ -174,7 +177,7 @@ struct unwind_hint {
 
 #ifndef __ASSEMBLY__
 
-#define UNWIND_HINT(sp_reg, sp_offset, type, end)	\
+#define UNWIND_HINT(sp_reg, sp_offset, type, signal, end) \
 	"\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
 #define STACK_FRAME_NON_STANDARD_FP(func)
@@ -182,7 +185,7 @@ struct unwind_hint {
 #define ASM_REACHABLE
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
-.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0 end=0
 .endm
 .macro STACK_FRAME_NON_STANDARD func:req
 .endm

tools/objtool/orc_dump.c

@@ -211,8 +211,8 @@ int orc_dump(const char *_objname)
 
 		print_reg(orc[i].bp_reg, bswap_if_needed(&dummy_elf, orc[i].bp_offset));
 
-		printf(" type:%s end:%d\n",
-		       orc_type_name(orc[i].type), orc[i].end);
+		printf(" type:%s signal:%d end:%d\n",
+		       orc_type_name(orc[i].type), orc[i].signal, orc[i].end);
 	}
 
 	elf_end(elf);