[PATCH v3] Eclair: scan the last xen-syms linking pass on Arm

[Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>]

The hide pattern .xen-syms.[013] leaves pass 2 visible. On x86
LAST_LINKING_PASS is 2, so that is the final link. On Arm
LAST_LINKING_PASS is 3 and the final image is .xen-syms.3. Pass 2 is
usually only a symlink, so Eclair saw no program link and reported every
translation unit as unreachable.

During analysis preparation, read LAST_LINKING_PASS from the architecture
makefile and the pass numbers from the foreach list in
xen/scripts/Makefile.link. Hide every pass except that one. An earlier
pass that is a real link stays hidden. The generator runs from
generate_ecl.sh, together with the other ECLAIR configuration scripts.

Fixes: a401b5c9dc35 ("Eclair: re-enable scanning of the (almost) final linking 
step")
Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
---
Test CI pipeline: 
https://gitlab.com/xen-project/people/dimaprkp4k/xen/-/pipelines/2940065908

Changes in v3:
- generate the hide pattern from generate_ecl.sh, which prepare.sh already runs

Link to v2:
https://patchew.org/Xen/e73c282694e68083305d03219f983bf74a8bf494.1791392326.git.dmytro._5Fprokopchuk1@xxxxxxxx/

Changes in v2:
- update commit message
- generate hide pattern before analysis
- read LAST_LINKING_PASS from the arch Makefile and pass numbers from the 
Makefile.link
---
 .../eclair_analysis/ECLAIR/analysis.ecl       |  2 +-
 .../ECLAIR/generate-xen-syms-passes.sh        | 20 +++++++++++++++++++
 .../eclair_analysis/ECLAIR/generate_ecl.sh    |  3 +++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100755 
automation/eclair_analysis/ECLAIR/generate-xen-syms-passes.sh

diff --git a/automation/eclair_analysis/ECLAIR/analysis.ecl 
b/automation/eclair_analysis/ECLAIR/analysis.ecl
index c6e1a7a95d..df1006bcaa 100644
--- a/automation/eclair_analysis/ECLAIR/analysis.ecl
+++ b/automation/eclair_analysis/ECLAIR/analysis.ecl
@@ -37,7 +37,7 @@ their Standard Library equivalents."
 -doc_begin="Do not analyze intermediate linking artifacts, as they do not 
differ from their final
 counterparts for the purposes of MISRA C static analysis."
 -file_tag+={xen_efi_tmp, "^xen/\\.xen\\.efi\\.([01]|alt\\..*)$"}
--file_tag+={xen_syms_tmp, "^xen/\\.xen-syms\\.[013]$"}
+-eval_file=xen_syms_passes.ecl
 -frames+={hide, "kind(program)&&target(xen_syms_tmp||xen_efi_tmp)"}
 -doc_end
 
diff --git a/automation/eclair_analysis/ECLAIR/generate-xen-syms-passes.sh 
b/automation/eclair_analysis/ECLAIR/generate-xen-syms-passes.sh
new file mode 100755
index 0000000000..e3795e8234
--- /dev/null
+++ b/automation/eclair_analysis/ECLAIR/generate-xen-syms-passes.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+
+# Hide every xen-syms linking pass except LAST_LINKING_PASS.
+# The pass list is the foreach in xen/scripts/Makefile.link.
+
+set -e
+
+cd "$(dirname "$0")"
+arch=$(echo "${XEN_TARGET_ARCH}" | sed -e 's/x86.*/x86/' -e 's/arm.*/arm/')
+last=$(sed -n 's/^LAST_LINKING_PASS *:= *\([0-9]\).*/\1/p' \
+    "../../../xen/arch/${arch}/Makefile" | head -n 1)
+passes=$(sed -n 's/.*foreach n,\([0-9 ]*\).*/\1/p' \
+    ../../../xen/scripts/Makefile.link | head -n 1)
+test -n "${last}"
+test -n "${passes}"
+hidden=$(printf '%s' "${passes}" | tr -d " ${last}")
+
+printf '%s\n' \
+    "-file_tag+={xen_syms_tmp, \"^xen/\\\\.xen-syms\\\\.[${hidden}]\$\"}" \
+    >xen_syms_passes.ecl
diff --git a/automation/eclair_analysis/ECLAIR/generate_ecl.sh 
b/automation/eclair_analysis/ECLAIR/generate_ecl.sh
index b955783904..b97fc55fd2 100755
--- a/automation/eclair_analysis/ECLAIR/generate_ecl.sh
+++ b/automation/eclair_analysis/ECLAIR/generate_ecl.sh
@@ -20,3 +20,6 @@ accepted_rst="${ECLAIR_PROJECT_ROOT}/docs/misra/rules.rst"
 
 # Generate the list of linker-defined symbols (must be run after a Xen build)
 "${script_dir}/generate-linker-symbols.sh"
+
+# Hide every xen-syms linking pass except LAST_LINKING_PASS.
+"${script_dir}/generate-xen-syms-passes.sh"
-- 
2.43.0