lwn.git/arch/x86/kernel/vmlinux.lds.S, branch v5.7-rc6

Merge branch 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-31T17:51:12+00:00

Pull x86 build updates from Ingo Molnar: "A handful of updates: two linker script cleanups and a stock defconfig+allmodconfig bootability fix" * 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/vdso: Discard .note.gnu.property sections in vDSO x86, vmlinux.lds: Add RUNTIME_DISCARD_EXIT to generic DISCARDS x86/Kconfig: Make CMDLINE_OVERRIDE depend on non-empty CMDLINE

x86, vmlinux.lds: Add RUNTIME_DISCARD_EXIT to generic DISCARDS

2020-03-27T10:52:11+00:00

In the x86 kernel, .exit.text and .exit.data sections are discarded at runtime, not by the linker. Add RUNTIME_DISCARD_EXIT to generic DISCARDS and define it in the x86 kernel linker script to keep them. The sections are added before the DISCARD directive so document here only the situation explicitly as this change doesn't have any effect on the generated kernel. Also, other architectures like ARM64 will use it too so generalize the approach with the RUNTIME_DISCARD_EXIT define. [ bp: Massage and extend commit message. ] Signed-off-by: H.J. Lu Signed-off-by: Borislav Petkov Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20200326193021.255002-1-hjl.tools@gmail.com

x86/vmlinux: Drop unneeded linker script discard of .eh_frame

2020-02-25T13:51:29+00:00

Now that .eh_frame sections for the files in setup.elf and realmode.elf are not generated anymore, the linker scripts don't need the special output section name /DISCARD/ any more. Remove the one in the main kernel linker script as well, since there are no .eh_frame sections already, and fix up a comment referencing .eh_frame. Update the comment in asm/dwarf2.h referring to .eh_frame so it continues to make sense, as well as being more specific. [ bp: Touch up commit message. ] Signed-off-by: Arvind Sankar Signed-off-by: Borislav Petkov Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Reviewed-by: Kees Cook Tested-by: Nathan Chancellor Link: https://lkml.kernel.org/r/20200224232129.597160-3-nivedita@alum.mit.edu

x86/vdso: Provide vdso_data offset on vvar_page

2020-01-14T11:20:57+00:00

VDSO support for time namespaces needs to set up a page with the same layout as VVAR. That timens page will be placed on position of VVAR page inside namespace. That page has vdso_data->seq set to 1 to enforce the slow path and vdso_data->clock_mode set to VCLOCK_TIMENS to enforce the time namespace handling path. To prepare the time namespace page the kernel needs to know the vdso_data offset. Provide arch_get_vdso_data() helper for locating vdso_data on VVAR page. Co-developed-by: Andrei Vagin Signed-off-by: Andrei Vagin Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20191112012724.250792-22-dima@arista.com

x86/vmlinux: Use INT3 instead of NOP for linker fill bytes

2019-11-04T18:10:08+00:00

Instead of using 0x90 (NOP) to fill bytes between functions, which makes it easier to sloppily target functions in function pointer overwrite attacks, fill with 0xCC (INT3) to force a trap. Also drop the space between "=" and the value to better match the binutils documentation https://sourceware.org/binutils/docs/ld/Output-Section-Fill.html#Output-Section-Fill Example "objdump -d" before: ... ffffffff810001e0 : ffffffff810001e0: 48 8b 25 e1 b1 51 01 mov 0x151b1e1(%rip),%rsp # ffffffff8251b3c8 ffffffff810001e7: e9 d5 fe ff ff jmpq ffffffff810000c1 ffffffff810001ec: 90 nop ffffffff810001ed: 90 nop ffffffff810001ee: 90 nop ffffffff810001ef: 90 nop ffffffff810001f0 <__startup_64>: ... After: ... ffffffff810001e0 : ffffffff810001e0: 48 8b 25 41 79 53 01 mov 0x1537941(%rip),%rsp # ffffffff82537b28 ffffffff810001e7: e9 d5 fe ff ff jmpq ffffffff810000c1 ffffffff810001ec: cc int3 ffffffff810001ed: cc int3 ffffffff810001ee: cc int3 ffffffff810001ef: cc int3 ffffffff810001f0 <__startup_64>: ... Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dave Hansen Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: linux-alpha@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-ia64@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: Michael Ellerman Cc: Michal Simek Cc: Rick Edgecombe Cc: Ross Zwisler Cc: Segher Boessenkool Cc: Thomas Gleixner Cc: Thomas Lendacky Cc: Will Deacon Cc: x86-ml Cc: Yoshinori Sato Link: https://lkml.kernel.org/r/20191029211351.13243-30-keescook@chromium.org

x86/vmlinux: Move EXCEPTION_TABLE to RO_DATA segment

2019-11-04T16:55:02+00:00

The exception table was needlessly marked executable. In preparation for execute-only memory, move the table into the RO_DATA segment via the new macro that can be used by any architectures that want to make a similar consolidation. Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dave Hansen Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: linux-alpha@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-ia64@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: Michael Ellerman Cc: Michal Simek Cc: Rick Edgecombe Cc: Ross Zwisler Cc: Segher Boessenkool Cc: Thomas Gleixner Cc: Thomas Lendacky Cc: Will Deacon Cc: x86-ml Cc: Yoshinori Sato Link: https://lkml.kernel.org/r/20191029211351.13243-17-keescook@chromium.org

x86/vmlinux: Actually use _etext for the end of the text segment

2019-11-04T16:54:16+00:00

Various calculations are using the end of the exception table (which does not need to be executable) as the end of the text segment. Instead, in preparation for moving the exception table into RO_DATA, move _etext after the exception table and update the calculations. Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dave Hansen Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: linux-alpha@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-ia64@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-s390@vger.kernel.org Cc: Michael Ellerman Cc: Michal Simek Cc: Nick Desaulniers Cc: Peter Zijlstra Cc: Rick Edgecombe Cc: Ross Zwisler Cc: Segher Boessenkool Cc: Thomas Gleixner Cc: Thomas Lendacky Cc: Will Deacon Cc: x86-ml Cc: Yoshinori Sato Link: https://lkml.kernel.org/r/20191029211351.13243-16-keescook@chromium.org

vmlinux.lds.h: Move NOTES into RO_DATA

2019-11-04T14:34:41+00:00

The .notes section should be non-executable read-only data. As such, move it to the RO_DATA macro instead of being per-architecture defined. Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Acked-by: Heiko Carstens # s390 Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dave Hansen Cc: linux-alpha@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-ia64@vger.kernel.org Cc: linux-s390@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: Michael Ellerman Cc: Michal Simek Cc: Rick Edgecombe Cc: Segher Boessenkool Cc: Will Deacon Cc: x86-ml Cc: Yoshinori Sato Link: https://lkml.kernel.org/r/20191029211351.13243-11-keescook@chromium.org

vmlinux.lds.h: Move Program Header restoration into NOTES macro

2019-11-04T14:34:39+00:00

In preparation for moving NOTES into RO_DATA, make the Program Header assignment restoration be part of the NOTES macro itself. Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Acked-by: Heiko Carstens # s390 Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dave Hansen Cc: linux-alpha@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-ia64@vger.kernel.org Cc: linux-s390@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: Michael Ellerman Cc: Michal Simek Cc: Rick Edgecombe Cc: Segher Boessenkool Cc: Will Deacon Cc: x86-ml Cc: Yoshinori Sato Link: https://lkml.kernel.org/r/20191029211351.13243-10-keescook@chromium.org

vmlinux.lds.h: Provide EMIT_PT_NOTE to indicate export of .notes

2019-11-04T14:34:38+00:00

In preparation for moving NOTES into RO_DATA, provide a mechanism for architectures that want to emit a PT_NOTE Program Header to do so. Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Acked-by: Heiko Carstens # s390 Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dave Hansen Cc: linux-alpha@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-c6x-dev@linux-c6x.org Cc: linux-ia64@vger.kernel.org Cc: linux-s390@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: Michael Ellerman Cc: Michal Simek Cc: Rick Edgecombe Cc: Segher Boessenkool Cc: Will Deacon Cc: x86-ml Cc: Yoshinori Sato Link: https://lkml.kernel.org/r/20191029211351.13243-9-keescook@chromium.org