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authorAlexander Gordeev <agordeev@linux.ibm.com>2022-07-24 15:02:16 +0200
committerVasily Gorbik <gor@linux.ibm.com>2022-09-14 16:46:01 +0200
commit2f0e8aae26a27fe73d033788f8e92188e7584f41 (patch)
tree07c8abbd98e7b51142126c6c5880eaeea65ccaf9 /arch/s390/include/asm/processor.h
parents390/dump: save IPL CPU registers once DAT is available (diff)
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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 'arch/s390/include/asm/processor.h')
-rw-r--r--arch/s390/include/asm/processor.h2
1 files changed, 0 insertions, 2 deletions
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 93677ae89e7e..4eb9b7875e13 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -306,8 +306,6 @@ static __always_inline void __noreturn disabled_wait(void)
#define ARCH_LOW_ADDRESS_LIMIT 0x7fffffffUL
-extern int memcpy_real(void *, unsigned long, size_t);
-
extern int s390_isolate_bp(void);
extern int s390_isolate_bp_guest(void);