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authorChristian Krinitsin <mail@krinitsin.com>2025-06-01 21:35:14 +0200
committerChristian Krinitsin <mail@krinitsin.com>2025-06-01 21:35:14 +0200
commit3e4c5a6261770bced301b5e74233e7866166ea5b (patch)
tree9379fddaba693ef8a045da06efee8529baa5f6f4 /gitlab/issues_text/target_arm/host_missing/accel_missing/1421
parente5634e2806195bee44407853c4bf8776f7abfa4f (diff)
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clean up repository
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-GDB memory reads fail on Cortex-M33
-Description of problem:
-GDB fails to read memory from the guest.  There appear to be at least two problems:
-
-1. In `arm_cpu_get_phys_page_attrs_debug`, `arm_is_secure(env)` returns false, because the implementation doesn't seem to know about Armv7-M or Armv8-M secure states.  However, `arm_mmu_idx(env)` does know how to check `env->v7m.secure`, so it returns `ARMMMUIdx_MSPriv` (the S stands for secure).  The mismatch between an apparently non-secure access to a secure MMU seems to cause the read to fail laster.
-2. With the MPU enabled (not the case in this repro, but I can provide one), `cpu_memory_rw_debug` computes `page = addr & TARGET_PAGE_MASK`, and uses the page to compute permissions.  However, TARGET_PAGE_MASK is based on 4K pages on this platform, but the MPU granularity is 32 bytes.  So the wrong page is used for checking.
-Steps to reproduce:
-```
-# Sorry for the large clone.  It's mostly unused files in CMSIS.
-git clone --recursive -b qemu-repro-1 https://github.com/dreiss/mpu_experiments
-cd mpu_experiments
-git checkout origin/qemu-repro-1
-cmake -S . -B build -DBOARD=qemu-mps2-an505 -DAPP=mpu_stacktrace -DCMAKE_BUILD_TYPE=Debug
-cmake --build build
-/path/to/qemu-system-arm -machine mps2-an505 -nographic -kernel build/kernel.elf -s -S -d int
-# Open a separate terminal and cd into mpu_experiments
-gdb build/kernel.elf -ex 'target remote :1234' -ex 'break base_case' -ex continue -ex backtrace -ex quit
-# Note the memory read failures in the backtrace.
-```