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ARC: dw2 unwind: switch to .eh_frame based unwinding
So finally after almost 8 years of dealing with .debug_frame, we are
finally switching to .eh_frame. The reason being stripped kernel
binaries had non-functional unwinder as .debug_frame was gone.
Also, in general .eh_frame seems more common way of doing unwinding.
This also folds a revert of f52e126cc7
("ARC: unwind: ensure that
.debug_frame is generated (vs. .eh_frame)") to ensure that we start
getting .eh_frame
Reported-by: Daniel Mentz <danielmentz@google.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
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@ -66,6 +66,8 @@ endif
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endif
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cflags-$(CONFIG_ARC_DW2_UNWIND) += -fasynchronous-unwind-tables
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# By default gcc 4.8 generates dwarf4 which kernel unwinder can't grok
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ifeq ($(atleast_gcc48),y)
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cflags-$(CONFIG_ARC_DW2_UNWIND) += -gdwarf-2
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@ -61,18 +61,6 @@ ENTRY(ret_from_fork)
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b ret_from_exception
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END(ret_from_fork)
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#ifdef CONFIG_ARC_DW2_UNWIND
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; Workaround for bug 94179 (STAR ):
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; Despite -fasynchronous-unwind-tables, linker is not making dwarf2 unwinder
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; section (.debug_frame) as loadable. So we force it here.
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; This also fixes STAR 9000487933 where the prev-workaround (objcopy --setflag)
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; would not work after a clean build due to kernel build system dependencies.
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.section .debug_frame, "wa",@progbits
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; Reset to .text as this file is included in entry-<isa>.S
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.section .text, "ax",@progbits
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#endif
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;################### Non TLB Exception Handling #############################
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; ---------------------------------------------
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@ -22,13 +22,9 @@ static inline void arc_write_me(unsigned short *addr, unsigned long value)
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*(addr + 1) = (value & 0xffff);
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}
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/* ARC specific section quirks - before relocation loop in generic loader
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*
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* For dwarf unwinding out of modules, this needs to
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* 1. Ensure the .debug_frame is allocatable (ARC Linker bug: despite
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* -fasynchronous-unwind-tables it doesn't).
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* 2. Since we are iterating thru sec hdr tbl anyways, make a note of
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* the exact section index, for later use.
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/*
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* This gets called before relocation loop in generic loader
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* Make a note of the section index of unwinding section
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*/
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int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
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char *secstr, struct module *mod)
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@ -40,8 +36,7 @@ int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
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mod->arch.unw_info = NULL;
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for (i = 1; i < hdr->e_shnum; i++) {
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if (strcmp(secstr+sechdrs[i].sh_name, ".debug_frame") == 0) {
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sechdrs[i].sh_flags |= SHF_ALLOC;
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if (strcmp(secstr+sechdrs[i].sh_name, ".eh_frame") == 0) {
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mod->arch.unw_sec_idx = i;
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break;
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}
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@ -111,7 +111,7 @@ UNW_REGISTER_INFO};
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#define DW_EH_PE_indirect 0x80
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#define DW_EH_PE_omit 0xff
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#define CIE_ID 0xffffffffUL
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#define CIE_ID 0
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typedef unsigned long uleb128_t;
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typedef signed long sleb128_t;
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@ -510,8 +510,7 @@ static const u32 *__cie_for_fde(const u32 *fde)
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{
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const u32 *cie;
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/* cie = fde + 1 - fde[1] / sizeof(*fde); */
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cie = (u32 *) fde[1];
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cie = fde + 1 - fde[1] / sizeof(*fde);
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return cie;
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}
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@ -84,7 +84,7 @@ SECTIONS
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/*
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* .exit.text is discard at runtime, not link time, to deal with
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* references from .debug_frame
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* references from unwinding sections
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* It will be init freed, being inside [__init_start : __init_end]
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*/
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.exit.text : { EXIT_TEXT }
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@ -120,18 +120,13 @@ SECTIONS
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#ifdef CONFIG_ARC_DW2_UNWIND
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. = ALIGN(PAGE_SIZE);
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.debug_frame : {
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.eh_frame : {
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__start_unwind = .;
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*(.debug_frame)
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*(.eh_frame)
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__end_unwind = .;
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}
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/*
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* gcc 4.8 generates this for -fasynchonous-unwind-tables,
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* while we still use the .debug_frame based unwinder
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*/
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/DISCARD/ : { *(.eh_frame) }
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#else
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/DISCARD/ : { *(.debug_frame) }
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/DISCARD/ : { *(.eh_frame) }
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#endif
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NOTES
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@ -148,7 +143,7 @@ SECTIONS
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}
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#ifndef CONFIG_DEBUG_INFO
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/* open-coded because we need .debug_frame seperately for unwinding */
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/DISCARD/ : { *(.debug_frame) }
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/DISCARD/ : { *(.debug_aranges) }
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/DISCARD/ : { *(.debug_pubnames) }
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/DISCARD/ : { *(.debug_info) }
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