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2015-12-29MIPS: VDSO: Fix build error with binutils 2.24 and earlierGuenter Roeck
Commit 2a037f310bab ("MIPS: VDSO: Fix build error") tries to fix a build error seen with binutils 2.24 and earlier. However, the fix does not work, and again results in the already known build errors if the kernel is built with an earlier version of binutils. CC arch/mips/vdso/gettimeofday.o /tmp/ccnOVbHT.s: Assembler messages: /tmp/ccnOVbHT.s:50: Error: can't resolve `_start' {*UND* section} - `L0 {.text section} /tmp/ccnOVbHT.s:374: Error: can't resolve `_start' {*UND* section} - `L0 {.text section} scripts/Makefile.build:258: recipe for target 'arch/mips/vdso/gettimeofday.o' failed make[2]: *** [arch/mips/vdso/gettimeofday.o] Error 1 Fixes: 2a037f310bab ("MIPS: VDSO: Fix build error") Cc: Qais Yousef <qais.yousef@imgtec.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/11926/ Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-12-22MIPS: VDSO: Fix build errorQais Yousef
Commit ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") introduced a build error. For MIPS VDSO to be compiled it requires binutils version 2.25 or above but the check in the Makefile had inverted logic causing it to be compiled in if binutils is below 2.25. This fixes the following compilation error: CC arch/mips/vdso/gettimeofday.o /tmp/ccsExcUd.s: Assembler messages: /tmp/ccsExcUd.s:62: Error: can't resolve `_start' {*UND* section} - `L0' {.text section} /tmp/ccsExcUd.s:467: Error: can't resolve `_start' {*UND* section} - `L0' {.text section} make[2]: *** [arch/mips/vdso/gettimeofday.o] Error 1 make[1]: *** [arch/mips/vdso] Error 2 make: *** [arch/mips] Error 2 [ralf@linux-mips: Fixed Sergei's complaint on the formatting of the cited commit and generally reformatted the log message.] Signed-off-by: Qais Yousef <qais.yousef@imgtec.com> Cc: alex@alex-smith.me.uk Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/11745/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-11-11MIPS: Initial implementation of a VDSOAlex Smith
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>