[PATCH v3 dwarves 8/9] tests: Validate inline BTF encoding

[Alan Maguire <alan.maguire@oracle.com>]

Exercise nested inline calls, constant arguments, no-argument inline
functions, and repeated inline call sites. Verify that ordinary wrapper
function BTF remains present, inline functions are annotated by pfunct,
and when bpftool is available, LOCSEC contains multiple inline sites.

Also verify that pfunct:

 - lists the ordinary and inline BTF functions;
 - prints inline-site parameter locations from detached raw BTF using
   the regN fallback;
 - uses an explicitly supplied ELF file to resolve register names and
   containing functions; and
 - automatically uses ELF information when BTF is embedded in the ELF.

Use a single-register inline parameter rather than asserting ABI-specific
register numbers or aggregate calling conventions, allowing the test to
run across supported architectures.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Assisted-by: Codex (GPT-5.6)
---
 tests/btf_inline.sh | 147 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 147 insertions(+)
 create mode 100755 tests/btf_inline.sh

diff --git a/tests/btf_inline.sh b/tests/btf_inline.sh
new file mode 100755
index 0000000..a782a65
--- /dev/null
+++ b/tests/btf_inline.sh
@@ -0,0 +1,147 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+
+script_dir=$(dirname "$0")
+source "$script_dir/test_lib.sh"
+
+outdir=$(make_tmpdir)
+trap cleanup EXIT
+
+title_log "Validation of additive inline BTF encoding."
+
+CC=${CC:-gcc}
+if ! command -v "$CC" >/dev/null 2>&1; then
+	info_log "skip: gcc not available"
+	test_skip
+fi
+
+if ! pahole --supported_btf_features | tr ',' '\n' | grep -Fxq inline; then
+	info_log "skip: pahole was built without BTF location support"
+	test_skip
+fi
+
+src=${outdir}/btf_inline.c
+obj=${outdir}/btf_inline
+btf=${outdir}/btf_inline.btf
+
+cat > "$src" <<'EOF'
+/* Keep the inline functions small enough to guarantee inlining at -O2. */
+static inline int scale(int value, int factor)
+{
+	return value * factor;
+}
+
+static inline int add_bias(int value, int bias)
+{
+	return scale(value, 2) + bias;
+}
+
+static volatile int inline_bias;
+
+static inline int add_global(void)
+{
+	return inline_bias;
+}
+
+static inline int combine(int value, int bias)
+{
+	return add_bias(value, bias) + add_global();
+}
+
+__attribute__((noinline)) int wrapper_once(int value, int bias)
+{
+	return combine(value, bias);
+}
+
+__attribute__((noinline)) int wrapper_twice(int value, int bias)
+{
+	return combine(value, bias) + combine(bias, value);
+}
+
+int main(void)
+{
+	return wrapper_once(1, 3) + wrapper_twice(2, 4);
+}
+EOF
+
+"$CC" -g -O2 -o "$obj" "$src"
+if [[ $? -ne 0 ]]; then
+	error_log "Could not compile $src"
+	test_fail
+fi
+
+if ! pahole --btf_features=default,inline --btf_encode_detached="$btf" "$obj"; then
+	error_log "Could not encode inline BTF for $obj"
+	test_fail
+fi
+
+# Inline location BTF augments the ordinary BTF_KIND_FUNC records for the
+# non-inline wrappers. It must cover nested calls, a constant parameter, a
+# no-argument inline function, and multiple call sites of the same inline.
+if ! pfunct --all --format_path=btf "$btf" 2>/dev/null | grep -Fq "int wrapper_once(int value, int bias);"; then
+	error_log "wrapper_once() is missing from inline BTF"
+	test_fail
+fi
+
+if ! pfunct --all --format_path=btf "$btf" 2>/dev/null | grep -Fq "int wrapper_twice(int value, int bias);"; then
+	error_log "wrapper_twice() is missing from inline BTF"
+	test_fail
+fi
+
+if ! pfunct --all --format_path=btf "$btf" 2>/dev/null | grep -Fq "inline int scale(int value, int factor);"; then
+	error_log "scale() inline location is missing from BTF"
+	test_fail
+fi
+
+if ! pfunct --all --format_path=btf "$btf" 2>/dev/null | grep -Fq "inline int add_bias(int value, int bias);"; then
+	error_log "add_bias() inline location is missing from BTF"
+	test_fail
+fi
+
+if ! pfunct --all --format_path=btf "$btf" 2>/dev/null | grep -Fq "inline int add_global(void);"; then
+	error_log "add_global() inline location is missing from BTF"
+	test_fail
+fi
+
+if ! pfunct --all --format_path=btf "$btf" 2>/dev/null | grep -Fq "inline int combine(int value, int bias);"; then
+	error_log "combine() inline location is missing from BTF"
+	test_fail
+fi
+
+if ! inline_sites=$(pfunct --inline_sites "$btf" 2>/dev/null) ||
+	   ! grep -Eq 'scale\(int value \[reg[0-9]+\], int factor \[const 0x2\]\)' <<<"$inline_sites"; then
+	error_log "pfunct did not render a fallback register name for an inline parameter"
+	test_fail
+fi
+
+if ! inline_sites=$(pfunct --inline_sites --elf "$obj" "$btf" 2>/dev/null) ||
+	   ! grep -Eq 'scale\(int value \[[^][,[:space:]]+\], int factor \[const 0x2\]\)' <<<"$inline_sites" ||
+	   grep -Eq 'scale\(int value \[reg[0-9]+\], int factor \[const 0x2\]\)' <<<"$inline_sites" ||
+	   ! grep -Eq '\[wrapper_once\+0x[0-9a-f]+, ' <<<"$inline_sites"; then
+	error_log "pfunct did not resolve inline-site registers and containing functions through ELF"
+	test_fail
+fi
+
+if command -v bpftool >/dev/null 2>&1; then
+	locsec_vlen=$(bpftool btf dump file "$btf" format raw 2>/dev/null |
+		     sed -n 's/.*LOCSEC .*vlen=\([0-9][0-9]*\).*/\1/p')
+	if [[ -z "$locsec_vlen" || "$locsec_vlen" -lt 2 ]]; then
+		error_log "multiple inline call sites are missing from LOCSEC"
+		test_fail
+	fi
+fi
+
+if ! pahole -J --btf_features=default,inline "$obj"; then
+	error_log "Could not encode embedded inline BTF for $obj"
+	test_fail
+fi
+
+if ! inline_sites=$(pfunct --inline_sites "$obj" 2>/dev/null) ||
+	   ! grep -Eq 'scale\(int value \[[^][,[:space:]]+\], int factor \[const 0x2\]\)' <<<"$inline_sites" ||
+	   grep -Eq 'scale\(int value \[reg[0-9]+\], int factor \[const 0x2\]\)' <<<"$inline_sites" ||
+	   ! grep -Eq '\[wrapper_once\+0x[0-9a-f]+, ' <<<"$inline_sites"; then
+	error_log "pfunct did not resolve inline-site registers and containing functions from embedded ELF BTF"
+	test_fail
+fi
+
+test_pass
-- 
2.43.5