18ad51dd34
We have a request for a fast method of getting CPU and NUMA node IDs from userspace. This patch implements a getcpu VDSO function, similar to x86. Ben suggested we use SPRG3 which is userspace readable. SPRG3 can be modified by a KVM guest, so we save the SPRG3 value in the paca and restore it when transitioning from the guest to the host. I have a glibc patch that implements sched_getcpu on top of this. Testing on a POWER7: baseline: 538 cycles vdso: 30 cycles Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
153 lines
3.7 KiB
ArmAsm
153 lines
3.7 KiB
ArmAsm
/*
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* This is the infamous ld script for the 64 bits vdso
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* library
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*/
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#include <asm/vdso.h>
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OUTPUT_FORMAT("elf64-powerpc", "elf64-powerpc", "elf64-powerpc")
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OUTPUT_ARCH(powerpc:common64)
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ENTRY(_start)
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SECTIONS
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{
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. = VDSO64_LBASE + SIZEOF_HEADERS;
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.hash : { *(.hash) } :text
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.gnu.hash : { *(.gnu.hash) }
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.dynsym : { *(.dynsym) }
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.dynstr : { *(.dynstr) }
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.gnu.version : { *(.gnu.version) }
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.gnu.version_d : { *(.gnu.version_d) }
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.gnu.version_r : { *(.gnu.version_r) }
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.note : { *(.note.*) } :text :note
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. = ALIGN(16);
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.text : {
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*(.text .stub .text.* .gnu.linkonce.t.* __ftr_alt_*)
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*(.sfpr .glink)
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} :text
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PROVIDE(__etext = .);
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PROVIDE(_etext = .);
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PROVIDE(etext = .);
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. = ALIGN(8);
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__ftr_fixup : { *(__ftr_fixup) }
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. = ALIGN(8);
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__mmu_ftr_fixup : { *(__mmu_ftr_fixup) }
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. = ALIGN(8);
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__lwsync_fixup : { *(__lwsync_fixup) }
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. = ALIGN(8);
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__fw_ftr_fixup : { *(__fw_ftr_fixup) }
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/*
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* Other stuff is appended to the text segment:
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*/
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.rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }
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.rodata1 : { *(.rodata1) }
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.dynamic : { *(.dynamic) } :text :dynamic
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.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
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.eh_frame : { KEEP (*(.eh_frame)) } :text
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.gcc_except_table : { *(.gcc_except_table) }
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.rela.dyn ALIGN(8) : { *(.rela.dyn) }
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.opd ALIGN(8) : { KEEP (*(.opd)) }
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.got ALIGN(8) : { *(.got .toc) }
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_end = .;
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PROVIDE(end = .);
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/*
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* Stabs debugging sections are here too.
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*/
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.stab 0 : { *(.stab) }
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.stabstr 0 : { *(.stabstr) }
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.stab.excl 0 : { *(.stab.excl) }
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.stab.exclstr 0 : { *(.stab.exclstr) }
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.stab.index 0 : { *(.stab.index) }
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.stab.indexstr 0 : { *(.stab.indexstr) }
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.comment 0 : { *(.comment) }
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/*
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* DWARF debug sections.
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* Symbols in the DWARF debugging sections are relative to the beginning
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* of the section so we begin them at 0.
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*/
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/* DWARF 1 */
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.debug 0 : { *(.debug) }
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.line 0 : { *(.line) }
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/* GNU DWARF 1 extensions */
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.debug_srcinfo 0 : { *(.debug_srcinfo) }
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.debug_sfnames 0 : { *(.debug_sfnames) }
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/* DWARF 1.1 and DWARF 2 */
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.debug_aranges 0 : { *(.debug_aranges) }
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.debug_pubnames 0 : { *(.debug_pubnames) }
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/* DWARF 2 */
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.debug_info 0 : { *(.debug_info .gnu.linkonce.wi.*) }
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.debug_abbrev 0 : { *(.debug_abbrev) }
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.debug_line 0 : { *(.debug_line) }
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.debug_frame 0 : { *(.debug_frame) }
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.debug_str 0 : { *(.debug_str) }
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.debug_loc 0 : { *(.debug_loc) }
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.debug_macinfo 0 : { *(.debug_macinfo) }
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/* SGI/MIPS DWARF 2 extensions */
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.debug_weaknames 0 : { *(.debug_weaknames) }
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.debug_funcnames 0 : { *(.debug_funcnames) }
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.debug_typenames 0 : { *(.debug_typenames) }
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.debug_varnames 0 : { *(.debug_varnames) }
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/DISCARD/ : {
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*(.note.GNU-stack)
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*(.branch_lt)
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*(.data .data.* .gnu.linkonce.d.* .sdata*)
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*(.bss .sbss .dynbss .dynsbss)
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}
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}
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/*
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* Very old versions of ld do not recognize this name token; use the constant.
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*/
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#define PT_GNU_EH_FRAME 0x6474e550
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/*
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* We must supply the ELF program headers explicitly to get just one
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* PT_LOAD segment, and set the flags explicitly to make segments read-only.
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*/
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PHDRS
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{
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text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
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dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
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note PT_NOTE FLAGS(4); /* PF_R */
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eh_frame_hdr PT_GNU_EH_FRAME;
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}
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/*
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* This controls what symbols we export from the DSO.
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*/
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VERSION
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{
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VDSO_VERSION_STRING {
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global:
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/*
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* Has to be there for the kernel to find
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*/
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__kernel_datapage_offset;
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__kernel_get_syscall_map;
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__kernel_gettimeofday;
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__kernel_clock_gettime;
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__kernel_clock_getres;
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__kernel_get_tbfreq;
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__kernel_sync_dicache;
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__kernel_sync_dicache_p5;
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__kernel_sigtramp_rt64;
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__kernel_getcpu;
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local: *;
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};
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}
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