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sh: Add support for DWARF GNU extensions 

Also, remove the "fix" to DW_CFA_def_cfa_register where we reset the
frame's cfa_offset to 0. This action is incorrect when handling
DW_CFA_def_cfa_register as the DWARF spec specifically states that the
previous contents of cfa_offset should be used with the new
register. The reason that I thought cfa_offset should be reset to 0 was
because it was being assigned a bogus value prior to executing the
DW_CFA_def_cfa_register op. It turns out that the bogus cfa_offset value
came from interpreting .cfi_escape pseudo-ops (those used by the GNU
extensions) as CFA_DW_def_cfa ops.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
hifive-unleashed-5.1
Matt Fleming 2009-08-16 01:44:33 +01:00
parent b955873bf5
commit cd7246f0e2
2 changed files with 17 additions and 1 deletions
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4
arch/sh/include/asm/dwarf.h
View File

@ -340,6 +340,10 @@ struct dwarf_stack {
#define DW_CFA_lo_user 0x1c
#define DW_CFA_hi_user 0x3f
/* GNU extension opcodes */
#define DW_CFA_GNU_args_size 0x2e
#define DW_CFA_GNU_negative_offset_extended 0x2f
/*
* Some call frame instructions encode their operands in the opcode. We
* need some helper functions to extract both the opcode and operands

14
arch/sh/kernel/dwarf.c
View File

@ -429,7 +429,6 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
count = dwarf_read_uleb128(current_insn,
&frame->cfa_register);
current_insn += count;
frame->cfa_offset = 0;
frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
break;
case DW_CFA_def_cfa_offset:
@ -465,6 +464,19 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
frame->regs[reg].flags |= DWARF_REG_OFFSET;
frame->regs[reg].addr = offset;
break;
case DW_CFA_GNU_args_size:
count = dwarf_read_uleb128(current_insn, &offset);
current_insn += count;
break;
case DW_CFA_GNU_negative_offset_extended:
count = dwarf_read_uleb128(current_insn, &reg);
current_insn += count;
count = dwarf_read_uleb128(current_insn, &offset);
offset *= cie->data_alignment_factor;
dwarf_frame_alloc_regs(frame, reg);
frame->regs[reg].flags |= DWARF_REG_OFFSET;
frame->regs[reg].addr = -offset;
break;
default:
pr_debug("unhandled DWARF instruction 0x%x\n", insn);
break;