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 /arch/s390/include | |
| 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 'arch/s390/include')
| -rw-r--r-- | arch/s390/include/asm/maccess.h | 14 | ||||
| -rw-r--r-- | arch/s390/include/asm/pgtable.h | 1 | ||||
| -rw-r--r-- | arch/s390/include/asm/processor.h | 2 |
3 files changed, 15 insertions, 2 deletions
diff --git a/arch/s390/include/asm/maccess.h b/arch/s390/include/asm/maccess.h new file mode 100644 index 000000000000..21ebd9bf34cc --- /dev/null +++ b/arch/s390/include/asm/maccess.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_S390_MACCESS_H +#define __ASM_S390_MACCESS_H + +#include <linux/types.h> + +struct iov_iter; + +extern unsigned long __memcpy_real_area; +void memcpy_real_init(void); +size_t memcpy_real_iter(struct iov_iter *iter, unsigned long src, size_t count); +int memcpy_real(void *dest, unsigned long src, size_t count); + +#endif /* __ASM_S390_MACCESS_H */ diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index 45617c966202..f1cb9391190d 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1780,6 +1780,7 @@ extern void vmem_remove_mapping(unsigned long start, unsigned long size); extern int __vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot, bool alloc); extern int vmem_map_4k_page(unsigned long addr, unsigned long phys, pgprot_t prot); extern void vmem_unmap_4k_page(unsigned long addr); +extern pte_t *vmem_get_alloc_pte(unsigned long addr, bool alloc); extern int s390_enable_sie(void); extern int s390_enable_skey(void); extern void s390_reset_cmma(struct mm_struct *mm); 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); |