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Commit 5580e904 authored by Matt Fleming's avatar Matt Fleming
Browse files

sh: Handle the DWARF op, DW_CFA_undefined 



Allow a DWARF register to have an undefined value. When applied to the
DWARF return address register this lets lets us label a function as
having no direct caller, e.g. kernel_thread_helper().

Signed-off-by: default avatarMatt Fleming <matt@console-pimps.org>
parent 5480675d

arch/sh/include/asm/dwarf.h

+3 −0
Original line number Diff line number Diff line
@@ -297,6 +297,7 @@ struct dwarf_reg { 
	unsigned long flags;

#define DWARF_REG_OFFSET	(1 << 0)

#define DWARF_VAL_OFFSET	(1 << 1)

#define DWARF_UNDEFINED		(1 << 2)

};



/*
@@ -370,6 +371,7 @@ extern struct dwarf_frame *dwarf_unwind_stack(unsigned long, 
#define CFI_DEF_CFA	.cfi_def_cfa

#define CFI_REGISTER	.cfi_register

#define CFI_REL_OFFSET	.cfi_rel_offset

#define CFI_UNDEFINED	.cfi_undefined



#else
@@ -383,6 +385,7 @@ extern struct dwarf_frame *dwarf_unwind_stack(unsigned long, 
#define CFI_DEF_CFA	CFI_IGNORE

#define CFI_REGISTER	CFI_IGNORE

#define CFI_REL_OFFSET	CFI_IGNORE

#define CFI_UNDEFINED	CFI_IGNORE



#ifndef __ASSEMBLY__

static inline void dwarf_unwinder_init(void)

arch/sh/kernel/dwarf.c

+11 −2
Original line number Diff line number Diff line
@@ -452,6 +452,8 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start, 
		case DW_CFA_undefined:

			count = dwarf_read_uleb128(current_insn, &reg);

			current_insn += count;

			regp = dwarf_frame_alloc_reg(frame, reg);

			regp->flags |= DWARF_UNDEFINED;

			break;

		case DW_CFA_def_cfa:

			count = dwarf_read_uleb128(current_insn,
@@ -629,9 +631,16 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc, 
		UNWINDER_BUG();

	}



	/* If we haven't seen the return address reg, we're screwed. */

	reg = dwarf_frame_reg(frame, DWARF_ARCH_RA_REG);

	UNWINDER_BUG_ON(!reg);



	/*

	 * If we haven't seen the return address register or the return

	 * address column is undefined then we must assume that this is

	 * the end of the callstack.

	 */

	if (!reg || reg->flags == DWARF_UNDEFINED)

		goto bail;



	UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);



	addr = frame->cfa + reg->addr;