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authorMatt Fleming <matt@console-pimps.org>2009-08-20 19:53:49 +0100
committerMatt Fleming <matt@console-pimps.org>2009-08-21 13:04:11 +0100
commit5580e9044df9c0e87861739d8c527006ead92e52 (patch)
treeef7c280cbc9e5b9f22170485cf05e7ebbe6c01f5 /arch
parent5480675dc60c7dda7146e506981b2b40a775cc1e (diff)
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: Matt Fleming <matt@console-pimps.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/sh/include/asm/dwarf.h3
-rw-r--r--arch/sh/kernel/dwarf.c13
2 files changed, 14 insertions, 2 deletions
diff --git a/arch/sh/include/asm/dwarf.h b/arch/sh/include/asm/dwarf.h
index 8b0bcc08738..c367ed3373c 100644
--- a/arch/sh/include/asm/dwarf.h
+++ b/arch/sh/include/asm/dwarf.h
@@ -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)
diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index e6f427cff5b..577302f31e6 100644
--- a/arch/sh/kernel/dwarf.c
+++ b/arch/sh/kernel/dwarf.c
@@ -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;