- 11 11月, 2015 1 次提交
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由 Alex Smith 提交于
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: NAlex Smith <alex.smith@imgtec.com> Signed-off-by: NMarkos 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: NRalf Baechle <ralf@linux-mips.org>
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- 24 11月, 2014 1 次提交
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由 Prem Karat 提交于
Based on commit 1091458d (mmap randomization) For 32-bit address spaces randomize within a 16MB space, for 64-bit within a 256MB space. Test Results: ------------ Without Patch (VDSO is not randomized) --------------------------------------- root@Maleo:~# ./aslr vdso FAIL: ASLR not functional (vdso always at 0x7fff7000) root@Maleo:~# ./aslr rekey vdso pre_val==cur_val value=0x7fff7000 With patch:(VDSO is randmoized and doesn't interfere with stack) ---------------------------------------------------------------- root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7f830ea2 current_value=0x776e2000 root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7fb0cea2 current_value=0x77209000 root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7f985ea2 current_value=0x7770c000 root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7fbc6ea2 current_value=0x7fe25000 Maps file output: ------------------------- root@cavium-octeon2:~# ./aslr rekey maps 78584000-785a5000 rwxp 00000000 00:00 0 [heap] 7f9d0000-7f9f1000 rw-p 00000000 00:00 0 [stack] 7ffa5000-7ffa6000 r-xp 00000000 00:00 0 [vdso] root@cavium-octeon2:~# ./aslr rekey maps 77de0000-77e01000 rwxp 00000000 00:00 0 [heap] 7f91b000-7f93c000 rw-p 00000000 00:00 0 [stack] 7ff99000-7ff9a000 r-xp 00000000 00:00 0 [vdso] root@cavium-octeon2:~# ./aslr rekey maps 77d7f000-77da0000 rwxp 00000000 00:00 0 [heap] 7fc2a000-7fc4b000 rw-p 00000000 00:00 0 [stack] 7fe09000-7fe0a000 r-xp 00000000 00:00 0 [vdso] root@cavium-octeon2:~# ./aslr rekey maps 7794c000-7794d000 r-xp 00000000 00:00 0 [vdso] 77e4b000-77e6c000 rwxp 00000000 00:00 0 [heap] 7f6e7000-7f708000 rw-p 00000000 00:00 0 [stack] root@cavium-octeon2:~# Signed-off-by: NPrem Karat <pkarat@mvista.com> Cc: linux-mips@linux-mips.org Cc: sergei.shtylyov@cogentembedded.com Cc: ddaney.cavm@gmail.com Patchwork: https://patchwork.linux-mips.org/patch/6812Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
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- 24 3月, 2012 1 次提交
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由 Jason Baron 提交于
The motivation for this patchset was that I was looking at a way for a qemu-kvm process, to exclude the guest memory from its core dump, which can be quite large. There are already a number of filter flags in /proc/<pid>/coredump_filter, however, these allow one to specify 'types' of kernel memory, not specific address ranges (which is needed in this case). Since there are no more vma flags available, the first patch eliminates the need for the 'VM_ALWAYSDUMP' flag. The flag is used internally by the kernel to mark vdso and vsyscall pages. However, it is simple enough to check if a vma covers a vdso or vsyscall page without the need for this flag. The second patch then replaces the 'VM_ALWAYSDUMP' flag with a new 'VM_NODUMP' flag, which can be set by userspace using new madvise flags: 'MADV_DONTDUMP', and unset via 'MADV_DODUMP'. The core dump filters continue to work the same as before unless 'MADV_DONTDUMP' is set on the region. The qemu code which implements this features is at: http://people.redhat.com/~jbaron/qemu-dump/qemu-dump.patch In my testing the qemu core dump shrunk from 383MB -> 13MB with this patch. I also believe that the 'MADV_DONTDUMP' flag might be useful for security sensitive apps, which might want to select which areas are dumped. This patch: The VM_ALWAYSDUMP flag is currently used by the coredump code to indicate that a vma is part of a vsyscall or vdso section. However, we can determine if a vma is in one these sections by checking it against the gate_vma and checking for a non-NULL return value from arch_vma_name(). Thus, freeing a valuable vma bit. Signed-off-by: NJason Baron <jbaron@redhat.com> Acked-by: NRoland McGrath <roland@hack.frob.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Avi Kivity <avi@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 27 7月, 2010 2 次提交
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由 David Daney 提交于
Quoting from Jiri Slaby's patch of a similar nature for x86: When initrd is in use and a driver does request_module() in its module_init (i.e. __initcall or device_initcall), a modprobe process is created with VDSO mapping. But VDSO is inited even in __initcall, i.e. on the same level (at the same time), so it may not be inited yet (link order matters). Move init_vdso up to subsys_initcall to avoid the issue. Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Cc: David Daney <ddaney@caviumnetworks.com> Cc: Jiri Slaby <jslaby@suse.cz> Patchwork: http://patchwork.linux-mips.org/patch/1386/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
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由 David Daney 提交于
In addition to being useless, it was mis-spelled. Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Cc: David Daney <ddaney@caviumnetworks.com> Patchwork: http://patchwork.linux-mips.org/patch/1385/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
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- 13 4月, 2010 1 次提交
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由 David Daney 提交于
This is a preliminary patch to add a vdso to all user processes. Still missing are ELF headers and .eh_frame information. But it is enough to allow us to move signal trampolines off of the stack. Note that emulation of branch delay slots in the FPU emulator still requires the stack. We allocate a single page (the vdso) and write all possible signal trampolines into it. The stack is moved down by one page and the vdso is mapped into this space. Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com> To: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/975/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>
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