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authorLinus Torvalds <torvalds@linux-foundation.org>2020-03-31 10:05:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-03-31 10:05:01 -0700
commit3cd86a58f7734bf9cef38f6f899608ebcaa3da13 (patch)
tree6ae5b8109011ee40deef645a9701e2d8dc4e4fce /mm
parenta8222fd5b80c7ec83f257060670becbeea9b50b9 (diff)
parentb2a84de2a2deb76a6a51609845341f508c518c03 (diff)
Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas: "The bulk is in-kernel pointer authentication, activity monitors and lots of asm symbol annotations. I also queued the sys_mremap() patch commenting the asymmetry in the address untagging. Summary: - In-kernel Pointer Authentication support (previously only offered to user space). - ARM Activity Monitors (AMU) extension support allowing better CPU utilisation numbers for the scheduler (frequency invariance). - Memory hot-remove support for arm64. - Lots of asm annotations (SYM_*) in preparation for the in-kernel Branch Target Identification (BTI) support. - arm64 perf updates: ARMv8.5-PMU 64-bit counters, refactoring the PMU init callbacks, support for new DT compatibles. - IPv6 header checksum optimisation. - Fixes: SDEI (software delegated exception interface) double-lock on hibernate with shared events. - Minor clean-ups and refactoring: cpu_ops accessor, cpu_do_switch_mm() converted to C, cpufeature finalisation helper. - sys_mremap() comment explaining the asymmetric address untagging behaviour" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (81 commits) mm/mremap: Add comment explaining the untagging behaviour of mremap() arm64: head: Convert install_el2_stub to SYM_INNER_LABEL arm64: Introduce get_cpu_ops() helper function arm64: Rename cpu_read_ops() to init_cpu_ops() arm64: Declare ACPI parking protocol CPU operation if needed arm64: move kimage_vaddr to .rodata arm64: use mov_q instead of literal ldr arm64: Kconfig: verify binutils support for ARM64_PTR_AUTH lkdtm: arm64: test kernel pointer authentication arm64: compile the kernel with ptrauth return address signing kconfig: Add support for 'as-option' arm64: suspend: restore the kernel ptrauth keys arm64: __show_regs: strip PAC from lr in printk arm64: unwind: strip PAC from kernel addresses arm64: mask PAC bits of __builtin_return_address arm64: initialize ptrauth keys for kernel booting task arm64: initialize and switch ptrauth kernel keys arm64: enable ptrauth earlier arm64: cpufeature: handle conflicts based on capability arm64: cpufeature: Move cpu capability helpers inside C file ...
Diffstat (limited to 'mm')
-rw-r--r--mm/mremap.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index af363063ea23..d28f08a36b96 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -606,6 +606,16 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
LIST_HEAD(uf_unmap_early);
LIST_HEAD(uf_unmap);
+ /*
+ * There is a deliberate asymmetry here: we strip the pointer tag
+ * from the old address but leave the new address alone. This is
+ * for consistency with mmap(), where we prevent the creation of
+ * aliasing mappings in userspace by leaving the tag bits of the
+ * mapping address intact. A non-zero tag will cause the subsequent
+ * range checks to reject the address as invalid.
+ *
+ * See Documentation/arm64/tagged-address-abi.rst for more information.
+ */
addr = untagged_addr(addr);
if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))