linux.git/arch/s390/boot, branch v5.14

s390/boot: fix zstd build for -march=z900

2021-07-30T15:08:22+00:00

zstd decompression uses __builtin_clz() which fails back to __clzdi2()
when the kernel is built for older hardware like z900. This leads to
build failures like the following:
s390x-11.1.0-ld: /devel/src/kernel/arch/s390/boot/compressed/../../../../lib/zstd/bitstream.h:148: undefined reference to `__clzdi2'

Fix that by optionally including lib/clz_ctz.c into the decompressor.

Reported-by: kernel test robot 
Fixes: 7b034d9c1b08 ("s390/boot: add zstd support")
Signed-off-by: Vasily Gorbik 
Link: https://lore.kernel.org/r/patch-1.thread-f0f589.git-f0f58936888f.your-ad-here.call-01627564869-ext-2765@work.hours
Signed-off-by: Heiko Carstens

s390/boot: fix use of expolines in the DMA code

2021-07-20T15:59:40+00:00

The DMA code section of the decompressor must be compiled with expolines
if Spectre V2 mitigation has been enabled for the decompressed kernel.
This is required because although the decompressor's image contains
the DMA code section, it is handed over to the decompressed kernel for use.

Because the DMA code is already slow w/o expolines, use expolines always
regardless whether the decompressed kernel is using them or not. This
simplifies the DMA code by dropping the conditional compilation of
expolines.

Fixes: bf72630130c2 ("s390: use proper expoline sections for .dma code")
Cc:  # 5.2
Signed-off-by: Alexander Egorenkov 
Reviewed-by: Heiko Carstens 
Signed-off-by: Heiko Carstens

s390/boot: replace magic string check with a bootdata flag

2021-07-05T10:44:23+00:00

The magic string "S390EP" at offset 0x10008 indicated to the decompressed
kernel that it was booted by the decompressor. Introduce a new bootdata
flag instead which conveys the same information in an explicit and
a cleaner way. But keep the magic string because it is a kernel ABI.

Signed-off-by: Alexander Egorenkov 
Reviewed-by: Vasily Gorbik 
Signed-off-by: Vasily Gorbik

s390: mm: Fix secure storage access exception handling

2021-07-05T10:44:23+00:00

Turns out that the bit 61 in the TEID is not always 1 and if that's
the case the address space ID and the address are
unpredictable. Without an address and its address space ID we can't
export memory and hence we can only send a SIGSEGV to the process or
panic the kernel depending on who caused the exception.

Unfortunately bit 61 is only reliable if we have the "misc" UV feature
bit.

Signed-off-by: Janosch Frank 
Reviewed-by: Christian Borntraeger 
Fixes: 084ea4d611a3d ("s390/mm: add (non)secure page access exceptions handlers")
Cc: stable@vger.kernel.org
Signed-off-by: Vasily Gorbik

s390/mem_detect: fix tprot() program check new psw handling

2021-06-18T14:41:24+00:00

The tprot() inline asm temporarily changes the program check new psw
to redirect a potential program check on the diag instruction.
Restoring of the program check new psw is done in C code behind the
inline asm.

This can be problematic, especially if the function is inlined, since
the compiler can reorder instructions in such a way that a different
instruction, which may result in a program check, might be executed
before the program check new psw has been restored.

To avoid such a scenario move restoring into the inline asm. For
consistency reasons move also saving of the original program check new
psw into the inline asm.

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

s390/mem_detect: use register pair instead of register asm

2021-06-18T14:41:24+00:00

...and slightly cleanup the inline asm.

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

s390/mem_detect: fix diag260() program check new psw handling

2021-06-18T14:41:24+00:00

The __diag260() inline asm temporarily changes the program check new
psw to redirect a potential program check on the diag instruction.
Restoring of the program check new psw is done in C code behind the
inline asm.

This can be problematic, especially if the function is inlined, since
the compiler can reorder instructions in such a way that a different
instruction, which may result in a program check, might be executed
before the program check new psw has been restored.

To avoid such a scenario move restoring into the inline asm. For
consistency reasons move also saving of the original program check new
psw into the inline asm.

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

s390/ipl_parm: use register pair instead of register asm

2021-06-18T14:41:23+00:00

...and slightly cleanup the inline asm.

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

s390/ipl_parm: fix program check new psw handling

2021-06-18T14:41:23+00:00

The __diag308() inline asm temporarily changes the program check new
psw to redirect a potential program check on the diag instruction.
Restoring of the program check new psw is done in C code behind the
inline asm.

This can be problematic, especially if the function is inlined, since
the compiler can reorder instructions in such a way that a different
instruction, which may result in a program check, might be executed
before the program check new psw has been restored.

To avoid such a scenario move restoring into the inline asm. For
consistency reasons move also saving of the original program check new
psw into the inline asm.

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

s390/boot: add zstd support

2021-06-18T14:41:22+00:00

Enable ztsd support in s390/boot, to enable booting with zstd
compressed kernel when configured with CONFIG_KERNEL_ZSTD=y.

BOOT_HEAP_SIZE is defined to 0x30000 in this case. Actual decompressor
memory usage with allyesconfig is currently 0x26150.

BugLink: https://bugs.launchpad.net/bugs/1931725
Signed-off-by: Dimitri John Ledkov 
cc: Heiko Carstens 
cc: Vasily Gorbik 
cc: Christian Borntraeger 
cc: linux-s390@vger.kernel.org
Link: https://lore.kernel.org/r/20210615114150.325080-1-dimitri.ledkov@canonical.com
[gor: added BOOT_HEAP_SIZE for zstd]
Signed-off-by: Vasily Gorbik