riscv64: fix ifuncs, improve the ifunc tests.
Talking futher to the person doing the glibc risc-v ifunc work, they
clarified that glibc _is_ passing hwcap as the first argument, and the
null pointer is actually the second argument.
https://sourceware.org/pipermail/libc-alpha/2023-August/150967.html
So since our whole purpose here was source compatibility, let's do what
they're actually doing, and let's add some tests. I've also added a test
that __riscv_hwprobe() works from an ifunc resolver because that's one
place where it might well be used. That said, one other thing that came
out of the discussion is that I actually went away and looked at a
sample of top apps to see how many are using ifuncs currently. The
result? Zero. So although this _might_ be interesting long term
(especially if clang gets riscv64 FMV), I think we've done more than we
need to with riscv64 ifuncs for now!
Test: ran locally, both dynamic and static tests
Change-Id: Ie2044d9f4e47c32c00ad381f045c537f4df38b08
diff --git a/tests/ifunc_test.cpp b/tests/ifunc_test.cpp
index e3c437e..1fdbf1a 100644
--- a/tests/ifunc_test.cpp
+++ b/tests/ifunc_test.cpp
@@ -60,6 +60,26 @@
return ret42;
}
+#elif defined(__riscv)
+
+#include <sys/hwprobe.h>
+
+static uint64_t g_hwcap;
+
+static riscv_hwprobe g_hwprobes[] = {{.key = RISCV_HWPROBE_KEY_IMA_EXT_0}};
+
+extern "C" fn_ptr_t hwcap_resolver(uint64_t hwcap, void* null) {
+ // Check hwcap like arm32/arm64.
+ g_hwcap = hwcap;
+
+ // For now, the pointer argument is reserved for future expansion.
+ if (null != NULL) abort();
+
+ // Ensure that __riscv_hwprobe() can be called from an ifunc.
+ if (__riscv_hwprobe(g_hwprobes, 1, 0, nullptr, 0) != 0) return nullptr;
+ return ret42;
+}
+
#else
extern "C" fn_ptr_t hwcap_resolver() {
@@ -81,6 +101,12 @@
EXPECT_EQ(getauxval(AT_HWCAP2), g_arg._hwcap2);
#elif defined(__arm__)
EXPECT_EQ(getauxval(AT_HWCAP), g_hwcap);
+#elif defined(__riscv)
+ EXPECT_EQ(getauxval(AT_HWCAP), g_hwcap);
+
+ riscv_hwprobe probes[] = {{.key = RISCV_HWPROBE_KEY_IMA_EXT_0}};
+ ASSERT_EQ(0, __riscv_hwprobe(probes, 1, 0, nullptr, 0));
+ EXPECT_EQ(probes[0].value, g_hwprobes[0].value);
#endif
}