]> git.karo-electronics.de Git - linux-beck.git/commit
MIPS: Initial implementation of a VDSO
authorAlex Smith <alex.smith@imgtec.com>
Wed, 21 Oct 2015 08:54:38 +0000 (09:54 +0100)
committerRalf Baechle <ralf@linux-mips.org>
Wed, 11 Nov 2015 07:36:36 +0000 (08:36 +0100)
commitebb5e78cc63417a35254a791de66e1cc84f963cc
tree49814946abe594cb8e7a11ce8d0a5fdaabb49d31
parent22773aa9b95657f0adc2b5342428d9da7a6d5d02
MIPS: Initial implementation of a VDSO

Add an initial implementation of a proper (i.e. an ELF shared library)
VDSO. With this commit it does not export any symbols, it only replaces
the current signal return trampoline page. A later commit will add user
implementations of gettimeofday()/clock_gettime().

To support both new toolchains and old ones which don't generate ABI
flags section, we define its content manually and then use a tool
(genvdso) to patch up the section to have the correct name and type.
genvdso also extracts symbol offsets ({,rt_}sigreturn) needed by the
kernel, and generates a C file containing a "struct mips_vdso_image"
containing both the VDSO data and these offsets. This C file is
compiled into the kernel.

On 64-bit kernels we require a different VDSO for each supported ABI,
so we may build up to 3 different VDSOs. The VDSO to use is selected by
the mips_abi structure.

A kernel/user shared data page is created and mapped below the VDSO
image. This is currently empty, but will be used by the user time
function implementations which are added later.

[markos.chandras@imgtec.com:
- Add more comments
- Move abi detection in genvdso.h since it's the get_symbol function
that needs it.
- Add an R6 specific way to calculate the base address of VDSO in order
to avoid the branch instruction which affects performance.
- Do not patch .gnu.attributes since it's not needed for dynamic linking.
- Simplify Makefile a little bit.
- checkpatch fixes
- Restrict VDSO support for binutils < 2.25 for pre-R6
- Include atomic64.h for O32 variant on MIPS64]

Signed-off-by: Alex Smith <alex.smith@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Matthew Fortune <matthew.fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11337/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
19 files changed:
arch/mips/Kbuild
arch/mips/include/asm/abi.h
arch/mips/include/asm/elf.h
arch/mips/include/asm/processor.h
arch/mips/include/asm/vdso.h
arch/mips/include/uapi/asm/Kbuild
arch/mips/include/uapi/asm/auxvec.h [new file with mode: 0644]
arch/mips/kernel/signal.c
arch/mips/kernel/signal32.c
arch/mips/kernel/signal_n32.c
arch/mips/kernel/vdso.c
arch/mips/vdso/.gitignore [new file with mode: 0644]
arch/mips/vdso/Makefile [new file with mode: 0644]
arch/mips/vdso/elf.S [new file with mode: 0644]
arch/mips/vdso/genvdso.c [new file with mode: 0644]
arch/mips/vdso/genvdso.h [new file with mode: 0644]
arch/mips/vdso/sigreturn.S [new file with mode: 0644]
arch/mips/vdso/vdso.h [new file with mode: 0644]
arch/mips/vdso/vdso.lds.S [new file with mode: 0644]