From ebb5e78cc63417a35254a791de66e1cc84f963cc Mon Sep 17 00:00:00 2001 From: Alex Smith Date: Wed, 21 Oct 2015 09:54:38 +0100 Subject: 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 Signed-off-by: Markos Chandras Cc: Matthew Fortune Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11337/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/processor.h | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'arch/mips/include/asm/processor.h') diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index 59ee6dcf6eed..3f832c3dd8f5 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -36,12 +36,6 @@ extern unsigned int vced_count, vcei_count; */ #define HAVE_ARCH_PICK_MMAP_LAYOUT 1 -/* - * A special page (the vdso) is mapped into all processes at the very - * top of the virtual memory space. - */ -#define SPECIAL_PAGES_SIZE PAGE_SIZE - #ifdef CONFIG_32BIT #ifdef CONFIG_KVM_GUEST /* User space process size is limited to 1GB in KVM Guest Mode */ @@ -80,7 +74,7 @@ extern unsigned int vced_count, vcei_count; #endif -#define STACK_TOP ((TASK_SIZE & PAGE_MASK) - SPECIAL_PAGES_SIZE) +#define STACK_TOP (TASK_SIZE & PAGE_MASK) /* * This decides where the kernel will search for a free chunk of vm -- cgit