diff options
| author | Alexander Gordeev <agordeev@linux.ibm.com> | 2022-07-24 15:02:16 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2022-09-14 16:46:01 +0200 |
| commit | 2f0e8aae26a27fe73d033788f8e92188e7584f41 (patch) | |
| tree | 07c8abbd98e7b51142126c6c5880eaeea65ccaf9 /drivers/s390 | |
| parent | 14a3a2624285d36624966935ec12f228d876c028 (diff) | |
s390/mm: rework memcpy_real() to avoid DAT-off mode
Function memcpy_real() is an univeral data mover that does not
require DAT mode to be able reading from a physical address.
Its advantage is an ability to read from any address, even
those for which no kernel virtual mapping exists.
Although memcpy_real() is interrupt-safe, there are no handlers
that make use of this function. The compiler instrumentation
have to be disabled and separate no-DAT stack used to allow
execution of the function once DAT mode is disabled.
Rework memcpy_real() to overcome these shortcomings. As result,
data copying (which is primarily reading out a crashed system
memory by a user process) is executed on a regular stack with
enabled interrupts. Also, use of memcpy_real_buf swap buffer
becomes unnecessary and the swapping is eliminated.
The above is achieved by using a fixed virtual address range
that spans a single page and remaps that page repeatedly when
memcpy_real() is called for a particular physical address.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'drivers/s390')
| -rw-r--r-- | drivers/s390/char/zcore.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/s390/char/zcore.c b/drivers/s390/char/zcore.c index f6da215ccf9f..6165e6aae762 100644 --- a/drivers/s390/char/zcore.c +++ b/drivers/s390/char/zcore.c @@ -30,6 +30,7 @@ #include <asm/checksum.h> #include <asm/os_info.h> #include <asm/switch_to.h> +#include <asm/maccess.h> #include "sclp.h" #define TRACE(x...) debug_sprintf_event(zcore_dbf, 1, x) |