On Tue, Feb 24, 2009 at 01:51:12AM -0500, Kyle McMartin wrote:
> From: Kyle McMartin <k...@redhat.com>
>
> On ppc64 (at least) gcc-4.4 is defaulting to generating .eh_frame
> sections, which are, for the kernel, fairly pointless. Additionally, on
> ppc64 this generates a relocation format which the kernel module loader
> does not currently support (R_PPC64_REL32.)
>
> Alexandre Oliva verifies that -fno-dwarf2-cfi-asm prevents this
> .eh_frame section from being generated.
>
> These seem to be used for unwinding, but it doesn't look like we
> currently use them anywhere. (In fact, we explicitly dump them in the
> x86_64 linker script.)
A grep for "eh_frame" shows too many hits in the kernel to convince
me this is true.
arch/m32r/kernel/vmlinux.lds.S: from .altinstructions and .eh_frame */
arch/mn10300/kernel/vmlinux.lds.S: from .altinstructions and .eh_frame */
arch/parisc/kernel/vmlinux.lds.S: * from .altinstructions and .eh_frame
arch/powerpc/kernel/vdso32/sigtramp.S: .section .eh_frame,"a",@progbits
arch/powerpc/kernel/vdso32/vdso32.lds.S: .eh_frame_hdr : {
*(.eh_frame_hdr) } :text :eh_frame_hdr
arch/powerpc/kernel/vdso32/vdso32.lds.S: .eh_frame : { KEEP
(*(.eh_frame)) }:text
arch/powerpc/kernel/vdso32/vdso32.lds.S: eh_frame_hdr PT_GNU_EH_FRAME;
arch/powerpc/kernel/vdso64/sigtramp.S: .section .eh_frame,"a",@progbits
arch/powerpc/kernel/vdso64/vdso64.lds.S: .eh_frame_hdr : {
*(.eh_frame_hdr) } :text :eh_frame_hdr
arch/powerpc/kernel/vdso64/vdso64.lds.S: .eh_frame : { KEEP
(*(.eh_frame)) }:text
arch/powerpc/kernel/vdso64/vdso64.lds.S: eh_frame_hdr PT_GNU_EH_FRAME;
arch/s390/kernel/vdso32/vdso32.lds.S: .eh_frame_hdr : { *(.eh_frame_hdr) }
:text :eh_frame_hdr
arch/s390/kernel/vdso32/vdso32.lds.S: .eh_frame : { KEEP (*(.eh_frame))
} :text
arch/s390/kernel/vdso32/vdso32.lds.S: eh_frame_hdr PT_GNU_EH_FRAME;
arch/s390/kernel/vdso64/vdso64.lds.S: .eh_frame_hdr : { *(.eh_frame_hdr) }
:text :eh_frame_hdr
arch/s390/kernel/vdso64/vdso64.lds.S: .eh_frame : { KEEP (*(.eh_frame))
} :text
arch/s390/kernel/vdso64/vdso64.lds.S: eh_frame_hdr PT_GNU_EH_FRAME;
arch/sh/kernel/vsyscall/vsyscall-sigreturn.S: .section .eh_frame,"a",@progbits
arch/sh/kernel/vsyscall/vsyscall-trapa.S: * fill out .eh_frame -- PFM. */
arch/sh/kernel/vsyscall/vsyscall-trapa.S: .section .eh_frame,"a",@progbits
arch/sh/kernel/vsyscall/vsyscall.lds.S: .eh_frame_hdr : { *(.eh_frame_hdr ) }
:text :eh_frame_hdr
arch/sh/kernel/vsyscall/vsyscall.lds.S: .eh_frame : {
arch/sh/kernel/vsyscall/vsyscall.lds.S: KEEP (*(.eh_frame))
arch/sh/kernel/vsyscall/vsyscall.lds.S: eh_frame_hdr PT_GNU_EH_FRAME;
arch/um/include/asm/common.lds.S: from .altinstructions and .eh_frame */
arch/um/kernel/dyn.lds.S: .eh_frame : { KEEP (*(.eh_frame)) }
arch/x86/kernel/vmlinux_32.lds.S: from .altinstructions and .eh_frame */
arch/x86/kernel/vmlinux_64.lds.S: from .altinstructions and .eh_frame */
arch/x86/kernel/vmlinux_64.lds.S: *(.eh_frame)
arch/x86/vdso/vdso-layout.lds.S: .eh_frame_hdr : { *(.eh_frame_hdr) }
:text :eh_frame_hdr
arch/x86/vdso/vdso-layout.lds.S: .eh_frame : { KEEP (*(.eh_frame))
} :text
arch/x86/vdso/vdso-layout.lds.S: eh_frame_hdr PT_GNU_EH_FRAME;
arch/x86/vdso/vdso32/int80.S: .section .eh_frame,"a",@progbits
arch/x86/vdso/vdso32/int80.S:VDSO32_vsyscall_eh_frame_size = 0x40
arch/x86/vdso/vdso32/int80.S: .space
VDSO32_vsyscall_eh_frame_size-(.LENDFDEDLSI-.LSTARTFRAMEDLSI), 0
arch/x86/vdso/vdso32/sigreturn.S: .section .eh_frame,"a",@progbits
arch/x86/vdso/vdso32/syscall.S: .section .eh_frame,"a",@progbits
arch/x86/vdso/vdso32/syscall.S:VDSO32_vsyscall_eh_frame_size = 0x40
arch/x86/vdso/vdso32/syscall.S: .space
VDSO32_vsyscall_eh_frame_size-(.LENDFDE1-.LSTARTFRAME), 0
arch/x86/vdso/vdso32/sysenter.S: .section .eh_frame,"a",@progbits
arch/x86/vdso/vdso32/sysenter.S: * Emit a symbol with the size of this
.eh_frame data,
arch/x86/vdso/vdso32/sysenter.S:VDSO32_vsyscall_eh_frame_size =
(.LENDFDEDLSI-.LSTARTFRAMEDLSI)
x86 has a specific ".section .eh_frame,"a",@progbits" in vdso32/int80.S as one
example.
Have you analyzed all these hits?
Sam
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