sema/boot: r391c OUT-PAGE-WIT resolution witness for the sum=0 readback class

The GR copy-out now prints, per changed page, the landing-table resolution
of the VA (the exact source the D2H reader's ledger-first branch uses) and
its first 8 bytes beside the write target hpa - a launch/readback
disagreement (write landed on another page/aperture than the reader
resolves) becomes one line instead of a forensics session.

Diagnostic only (bounded by the existing copywit budget).

1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/gsp_sema_service.h b/kernel/gsp_sema_service.h
index 063ed5c..cef7b0a 100644
--- a/kernel/gsp_sema_service.h
+++ b/kernel/gsp_sema_service.h
@@ -408,4 +408,14 @@ int gsp_sema_gr_reloc_resolve(u64 va, struct gsp_sema_gr_reloc *out);
 bool gsp_sema_gr_write_guard(u64 va, u64 hpa, const char *path);
 bool gsp_sema_write_guard(u64 va, u64 pa, u32 ap, const char *path);
 
+/*
+ * r391 diagnostic (sum=0 class): resolve a GR data VA through the landing
+ * table (the exact source the D2H reader's ledger-first branch uses) and
+ * return the resolution plus the first 8 bytes read through it. The GR
+ * copy-out prints it next to the write target it used, so a launch/readback
+ * disagreement (the write went to another page/aperture than the reader
+ * resolves) is one line instead of a forensics session.
+ */
+bool gsp_sema_gr_va_snap(u64 va, u64 *pa, u32 *ap, u64 *val8);
+
 #endif /* _GSP_SEMA_SERVICE_H_ */