plugins: force slow path when plugins instrument memory ops

The lack of SVE memory instrumentation has been an omission in plugin
handling since it was introduced. Fortunately we can utilise the
probe_* functions to force all all memory access to follow the slow
path. We do this by checking the access type and presence of plugin
memory callbacks and if set return the TLB_MMIO flag.

We have to jump through a few hoops in user mode to re-use the flag
but it was the desired effect:

 ./qemu-system-aarch64 -display none -serial mon:stdio \
   -M virt -cpu max -semihosting-config enable=on \
   -kernel ./tests/tcg/aarch64-softmmu/memory-sve \
   -plugin ./contrib/plugins/libexeclog.so,ifilter=st1w,afilter=0x40001808 -d plugin

gives (disas doesn't currently understand st1w):

  0, 0x40001808, 0xe54342a0, ".byte 0xa0, 0x42, 0x43, 0xe5", store, 0x40213010, RAM, store, 0x40213014, RAM, store, 0x40213018, RAM

And for user-mode:

  ./qemu-aarch64 \
    -plugin contrib/plugins/libexeclog.so,afilter=0x4007c0 \
    -d plugin \
    ./tests/tcg/aarch64-linux-user/sha512-sve

gives:

  1..10
  ok 1 - do_test(&tests[i])
  0, 0x4007c0, 0xa4004b80, ".byte 0x80, 0x4b, 0x00, 0xa4", load, 0x5500800370, load, 0x5500800371, load, 0x5500800372, load, 0x5500800373, load, 0x5500800374, load, 0x5500800375, load, 0x5500800376, load, 0x5500800377, load, 0x5500800378, load, 0x5500800379, load, 0x550080037a, load, 0x550080037b, load, 0x550080037c, load, 0x550080037d, load, 0x550080037e, load, 0x550080037f, load, 0x5500800380, load, 0x5500800381, load, 0x5500800382, load, 0x5500800383, load, 0x5500800384, load, 0x5500800385, load, 0x5500800386, lo
  ad, 0x5500800387, load, 0x5500800388, load, 0x5500800389, load, 0x550080038a, load, 0x550080038b, load, 0x550080038c, load, 0x550080038d, load, 0x550080038e, load, 0x550080038f, load, 0x5500800390, load, 0x5500800391, load, 0x5500800392, load, 0x5500800393, load, 0x5500800394, load, 0x5500800395, load, 0x5500800396, load, 0x5500800397, load, 0x5500800398, load, 0x5500800399, load, 0x550080039a, load, 0x550080039b, load, 0x550080039c, load, 0x550080039d, load, 0x550080039e, load, 0x550080039f, load, 0x55008003a0, load, 0x55008003a1, load, 0x55008003a2, load, 0x55008003a3, load, 0x55008003a4, load, 0x55008003a5, load, 0x55008003a6, load, 0x55008003a7, load, 0x55008003a8, load, 0x55008003a9, load, 0x55008003aa, load, 0x55008003ab, load, 0x55008003ac, load, 0x55008003ad, load, 0x55008003ae, load, 0x55008003af

(4007c0 is the ld1b in the sha512-sve)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Robert Henry <robhenry@microsoft.com>
Cc: Aaron Lindsay <aaron@os.amperecomputing.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230630180423.558337-20-alex.bennee@linaro.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 200c27e..5fa0687 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -464,6 +464,29 @@ int probe_access_full(CPUArchState *env, vaddr addr, int size,
                       MMUAccessType access_type, int mmu_idx,
                       bool nonfault, void **phost,
                       CPUTLBEntryFull **pfull, uintptr_t retaddr);
+
+/**
+ * probe_access_mmu() - Like probe_access_full except cannot fault and
+ * doesn't trigger instrumentation.
+ *
+ * @env: CPUArchState
+ * @vaddr: virtual address to probe
+ * @size: size of the probe
+ * @access_type: read, write or execute permission
+ * @mmu_idx: softmmu index
+ * @phost: ptr to return value host address or NULL
+ * @pfull: ptr to return value CPUTLBEntryFull structure or NULL
+ *
+ * The CPUTLBEntryFull structure returned via @pfull is transient
+ * and must be consumed or copied immediately, before any further
+ * access or changes to TLB @mmu_idx.
+ *
+ * Returns: TLB flags as per probe_access_flags()
+ */
+int probe_access_full_mmu(CPUArchState *env, vaddr addr, int size,
+                          MMUAccessType access_type, int mmu_idx,
+                          void **phost, CPUTLBEntryFull **pfull);
+
 #endif
 
 /* Hide the qatomic_read to make code a little easier on the eyes */