nrf_security: CRACEN: Fix alignment issue with nRF54LM20A

[degjorva]

Fix alignment of src data in sx_wrpkmem.
In some situations there would be unaligned data in ram. This would could cause a USAGE FAULT to appear.
Change it to use memcpy to read from src to guarante alignment.

[Copilot]

Pull request overview

This PR fixes an alignment issue in the sx_wrpkmem function for nRF54LM20A that could cause USAGE FAULT errors when source data is unaligned in RAM.

Key changes:

• Replaced problematic pointer arithmetic with cleaner cast-and-add operations
• Introduced memcpy to safely read from potentially unaligned source addresses
• Added documentation clarifying the alignment guarantees

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[NordicBuilder]

CI Information

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Build number: 3

Inputs:

Sources:

sdk-nrf: PR head: 4647d0b35a62989ae3ef326b4bb2d67471fbdba3

more details

sdk-nrf:

PR head: 4647d0b35a62989ae3ef326b4bb2d67471fbdba3
merge base: d40e9dc6b0f875c98a8a1425f106391866dd043f
target head (main): d0f84cb57d7e07a99e2cd487eeb8c0503dd579de
Diff

Github labels

Enabled	Name	Description
	ci-disabled	Disable the ci execution
	ci-all-test	Run all of ci, no test spec filtering will be done
	ci-force-downstream	Force execution of downstream even if twister fails
	ci-run-twister	Force run twister
	ci-run-zephyr-twister	Force run zephyr twister

List of changed files detected by CI (1)

subsys
│  ├── nrf_security
│  │  ├── src
│  │  │  ├── drivers
│  │  │  │  ├── cracen
│  │  │  │  │  ├── silexpk
│  │  │  │  │  │  ├── src
│  │  │  │  │  │  │  │ iomem.c

Outputs:

Toolchain

Version: 43683a87ea
Build docker image: docker-dtr.nordicsemi.no/sw-production/ncs-build:43683a87ea_5ea73affbf

Test Spec & Results: ✅ Success; ❌ Failure; 🟠 Queued; 🟡 Progress; ◻️ Skipped; ⚠️ Quarantine

• ◻️ Toolchain - Skipped: existing toolchain is used
• ✅ Build twister
  • sdk-nrf test count: 2571
• ✅ Integration tests
  • ✅ test-fw-nrfconnect-chip
  • ✅ test-fw-nrfconnect-nrf_crypto
  • ✅ test-fw-nrfconnect-rs
  • ✅ test-fw-nrfconnect-tfm
  • ✅ test-sdk-find-my
  • ✅ test-sdk-mcuboot
  • ✅ test-sdk-dfu
  • ⚠️ test_ble_nrf_config
  • ⚠️ test-fw-nrfconnect-nrf-iot_cloud

Disabled integration tests

• • test-fw-nrfconnect-nrf_lrcs_mosh
  • test-fw-nrfconnect-nrf_lrcs_positioning
  • desktop52_verification
  • test-fw-nrfconnect-apps
  • test-fw-nrfconnect-ble_mesh
  • test-fw-nrfconnect-ble_samples
  • test-fw-nrfconnect-fem
  • test-fw-nrfconnect-nfc
  • test-fw-nrfconnect-nrf-iot_libmodem-nrf
  • test-fw-nrfconnect-nrf-iot_lwm2m
  • test-fw-nrfconnect-nrf-iot_samples
  • test-fw-nrfconnect-nrf-iot_thingy91
  • test-fw-nrfconnect-nrf-iot_zephyr_lwm2m
  • test-fw-nrfconnect-ps-main
  • test-fw-nrfconnect-rpc
  • test-fw-nrfconnect-thread-main
  • test-low-level
  • test-sdk-audio
  • test-sdk-wifi
  • test-secdom-samples-public

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