linux.git/arch/s390/kernel/vmlinux.lds.S, branch v6.5

s390: make extables read-only

2023-04-04T16:34:55+00:00

Currently, exception tables are marked as ro_after_init. However,
since they are sorted during compile time using scripts/sorttable,
they can be moved to RO_DATA using the RO_EXCEPTION_TABLE_ALIGN macro,
which is specifically designed for this purpose.

Suggested-by: Heiko Carstens 
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/kasan: move shadow mapping to decompressor

2023-03-20T10:02:51+00:00

Since regular paging structs are initialized in decompressor already
move KASAN shadow mapping to decompressor as well. This helps to avoid
allocating KASAN required memory in 1 large chunk, de-duplicate paging
structs creation code and start the uncompressed kernel with KASAN
instrumentation right away. This also allows to avoid all pitfalls
accidentally calling KASAN instrumented code during KASAN initialization.

Acked-by: Heiko Carstens 
Reviewed-by: Alexander Gordeev 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens

Merge tag 's390-6.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2023-02-21T23:09:17+00:00

Pull s390 updates from Heiko Carstens:

 - Large cleanup of the con3270/tty3270 driver. Among others this fixes:
     - Background Color Support
     - ASCII Line Character Support
     - VT100 Support
     - Geometries other than 80x24

 - Cleanup and improve cmpxchg() code. Also add cmpxchg_user_key() to
   uaccess functions, which will be used by KVM to access KVM guest
   memory with a specific storage key

 - Add support for user space events counting to CPUMF

 - Cleanup the vfio/ccw code, which also allows now to properly support
   2K Format-2 IDALs

 - Move kernel page table allocation and initialization to decompressor,
   which finally allows to enter the kernel with dynamic address
   translation enabled. This in turn allows to get rid of code with
   special handling in the kernel, which has to distinguish if DAT is on
   or off

 - Replace kretprobe with rethook

 - Various improvements to vfio/ap queue resets:
     - Use TAPQ to verify completion of a reset in progress rather than
       multiple invocations of ZAPQ.
     - Check TAPQ response codes when verifying successful completion of
       ZAPQ.
     - Fix erroneous handling of some error response codes.
     - Increase the maximum amount of time to wait for successful
       completion of ZAPQ

 - Rework system call wrappers to get rid of alias functions, which were
   only left on s390

 - Cleanup diag288_wdt watchdog driver. It has been agreed on with
   Guenter Roeck that this goes upstream via the s390 tree

 - Add missing loadparm parameter handling for list-directed ECKD
   ipl/reipl

 - Various improvements to memory detection code

 - Remove arch_cpu_idle_time() since the current implementation is
   broken, and allows user space observable accounted idle times which
   can temporarily decrease

 - Add Reset DAT-Protection support: (only) allow to change PTEs from RO
   to RW with a new RDP instruction. Unlike the currently used IPTE
   instruction, this does not necessarily guarantee that TLBs of all
   CPUs are synchronously flushed; and that remote CPUs can see spurious
   protection faults. The overall improvement for not requiring an all
   CPU synchronization, like it is required with IPTE, should be
   beneficial

 - Fix KFENCE page fault reporting

 - Smaller cleanups and improvement all over the place

* tag 's390-6.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (182 commits)
  s390/irq,idle: simplify idle check
  s390/processor: add test_and_set_cpu_flag() and test_and_clear_cpu_flag()
  s390/processor: let cpu helper functions return boolean values
  s390/kfence: fix page fault reporting
  s390/zcrypt: introduce ctfm field in struct CPRBX
  s390: remove confusing comment from uapi types header file
  vfio/ccw: remove WARN_ON during shutdown
  s390/entry: remove toolchain dependent micro-optimization
  s390/mem_detect: do not truncate online memory ranges info
  s390/vx: remove __uint128_t type from __vector128 struct again
  s390/mm: add support for RDP (Reset DAT-Protection)
  s390/mm: define private VM_FAULT_* reasons from top bits
  Documentation: s390: correct spelling
  s390/ap: fix status returned by ap_qact()
  s390/ap: fix status returned by ap_aqic()
  s390: vfio-ap: tighten the NIB validity check
  Revert "s390/mem_detect: do not update output parameters on failure"
  s390/idle: remove arch_cpu_idle_time() and corresponding code
  s390/vx: use simple assignments to access __vector128 members
  s390/vx: add 64 and 128 bit members to __vector128 struct
  ...

Merge tag 'v6.2-rc6' into sched/core, to pick up fixes

2023-01-31T14:01:20+00:00

Pick up fixes before merging another batch of cpuidle updates.

Signed-off-by: Ingo Molnar

s390: discard .interp section

2023-01-25T19:51:10+00:00

When debugging vmlinux with QEMU + GDB, the following GDB error may
occur:

    (gdb) c
    Continuing.
    Warning:
    Cannot insert breakpoint -1.
    Cannot access memory at address 0xffffffffffff95c0

    Command aborted.
    (gdb)

The reason is that, when .interp section is present, GDB tries to
locate the file specified in it in memory and put a number of
breakpoints there (see enable_break() function in gdb/solib-svr4.c).
Sometimes GDB finds a bogus location that matches its heuristics,
fails to set a breakpoint and stops. This makes further debugging
impossible.

The .interp section contains misleading information anyway (vmlinux
does not need ld.so), so fix by discarding it.

Signed-off-by: Ilya Leoshkevich 
Cc: 
Signed-off-by: Heiko Carstens

Merge branch 'fixes' into features

2023-01-17T18:12:39+00:00

Signed-off-by: Heiko Carstens

s390/mm: start kernel with DAT enabled

2023-01-13T13:15:05+00:00

The setup of the kernel virtual address space is spread
throughout the sources, boot stages and config options
like this:

1. The available physical memory regions are queried
   and stored as mem_detect information for later use
   in the decompressor.

2. Based on the physical memory availability the virtual
   memory layout is established in the decompressor;

3. If CONFIG_KASAN is disabled the kernel paging setup
   code populates kernel pgtables and turns DAT mode on.
   It uses the information stored at step [1].

4. If CONFIG_KASAN is enabled the kernel early boot
   kasan setup populates kernel pgtables and turns DAT
   mode on. It uses the information stored at step [1].

   The kasan setup creates early_pg_dir directory and
   directly overwrites swapper_pg_dir entries to make
   shadow memory pages available.

Move the kernel virtual memory setup to the decompressor
and start the kernel with DAT turned on right from the
very first istruction. That completely eliminates the
boot phase when the kernel runs in DAT-off mode, simplies
the overall design and consolidates pgtables setup.

The identity mapping is created in the decompressor, while
kasan shadow mappings are still created by the early boot
kernel code.

Share with decompressor the existing kasan memory allocator.
It decreases the size of a newly requested memory block from
pgalloc_pos and ensures that kernel image is not overwritten.
pgalloc_low and pgalloc_pos pointers are made preserved boot
variables for that.

Use the bootdata infrastructure to setup swapper_pg_dir
and invalid_pg_dir directories used by the kernel later.
The interim early_pg_dir directory established by the
kasan initialization code gets eliminated as result.

As the kernel runs in DAT-on mode only the PSW_KERNEL_BITS
define gets PSW_MASK_DAT bit by default. Additionally, the
setup_lowcore_dat_off() and setup_lowcore_dat_on() routines
get merged, since there is no DAT-off mode stage anymore.

The memory mappings are created with RW+X protection that
allows the early boot code setting up all necessary data
and services for the kernel being booted. Just before the
paging is enabled the memory protection is changed to
RO+X for text, RO+NX for read-only data and RW+NX for
kernel data and the identity mapping.

Reviewed-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens

objtool/idle: Validate __cpuidle code as noinstr

2023-01-13T10:48:15+00:00

Idle code is very like entry code in that RCU isn't available. As
such, add a little validation.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar 
Tested-by: Tony Lindgren 
Tested-by: Ulf Hansson 
Acked-by: Geert Uytterhoeven 
Acked-by: Rafael J. Wysocki 
Acked-by: Frederic Weisbecker 
Link: https://lore.kernel.org/r/20230112195540.373461409@infradead.org

s390: define RUNTIME_DISCARD_EXIT to fix link error with GNU ld < 2.36

2023-01-06T15:38:21+00:00

Nathan Chancellor reports that the s390 vmlinux fails to link with
GNU ld < 2.36 since commit 99cb0d917ffa ("arch: fix broken BuildID
for arm64 and riscv").

It happens for defconfig, or more specifically for CONFIG_EXPOLINE=y.

  $ s390x-linux-gnu-ld --version | head -n1
  GNU ld (GNU Binutils for Debian) 2.35.2
  $ make -s ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- allnoconfig
  $ ./scripts/config -e CONFIG_EXPOLINE
  $ make -s ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- olddefconfig
  $ make -s ARCH=s390 CROSS_COMPILE=s390x-linux-gnu-
  `.exit.text' referenced in section `.s390_return_reg' of drivers/base/dd.o: defined in discarded section `.exit.text' of drivers/base/dd.o
  make[1]: *** [scripts/Makefile.vmlinux:34: vmlinux] Error 1
  make: *** [Makefile:1252: vmlinux] Error 2

arch/s390/kernel/vmlinux.lds.S wants to keep EXIT_TEXT:

        .exit.text : {
                EXIT_TEXT
        }

But, at the same time, EXIT_TEXT is thrown away by DISCARD because
s390 does not define RUNTIME_DISCARD_EXIT.

I still do not understand why the latter wins after 99cb0d917ffa,
but defining RUNTIME_DISCARD_EXIT seems correct because the comment
line in arch/s390/kernel/vmlinux.lds.S says:

        /*
         * .exit.text is discarded at runtime, not link time,
         * to deal with references from __bug_table
         */

Nathan also found that binutils commit 21401fc7bf67 ("Duplicate output
sections in scripts") cured this issue, so we cannot reproduce it with
binutils 2.36+, but it is better to not rely on it.

Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
Link: https://lore.kernel.org/all/Y7Jal56f6UBh1abE@dev-arch.thelio-3990X/
Reported-by: Nathan Chancellor 
Signed-off-by: Masahiro Yamada 
Link: https://lore.kernel.org/r/20230105031306.1455409-1-masahiroy@kernel.org
Signed-off-by: Heiko Carstens

s390: expicitly align _edata and _end symbols on page boundary

2023-01-06T15:38:21+00:00

Symbols _edata and _end in the linker script are the
only unaligned expicitly on page boundary. Although
_end is aligned implicitly by BSS_SECTION macro that
is still inconsistent and could lead to a bug if a tool
or function would assume that _edata is as aligned as
others.

For example, vmem_map_init() function does not align
symbols _etext, _einittext etc. Should these symbols
be unaligned as well, the size of ranges to update
were short on one page.

Instead of fixing every occurrence of this kind in the
code and external tools just force the alignment on
these two symbols.

Reviewed-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens