On 1/12/24 08:49, Vineet Gupta wrote:
Hi Richard, Alistair
On 10/30/23 14:17, Richard Henderson wrote:
diff --git a/linux-user/riscv/Makefile.vdso b/linux-user/riscv/Makefile.vdso
new file mode 100644
index 0000000000..2c257dbfda
--- /dev/null
+++ b/linux-user/riscv/Makefile.vdso
@@ -0,0 +1,15 @@
+include $(BUILD_DIR)/tests/tcg/riscv64-linux-user/config-target.mak
+
+SUBDIR = $(SRC_PATH)/linux-user/riscv
+VPATH += $(SUBDIR)
+
+all: $(SUBDIR)/vdso-32.so $(SUBDIR)/vdso-64.so
+
+LDFLAGS = -nostdlib -shared -fpic -Wl,-h,linux-vdso.so.1 -Wl,--build-id=sha1 \
+ -Wl,--hash-style=both -Wl,-T,$(SUBDIR)/vdso.ld
+
+$(SUBDIR)/vdso-32.so: vdso.S vdso.ld vdso-asmoffset.h
+ $(CC) -o $@ $(LDFLAGS) -mabi=ilp32d -march=rv32g $<
+
+$(SUBDIR)/vdso-64.so: vdso.S vdso.ld vdso-asmoffset.h
+ $(CC) -o $@ $(LDFLAGS) -mabi=lp64d -march=rv64g $<
So by default qemu ships the vdso binary. How can one rebuild it ?
From skimming the build files it seems following ought to do it
make update-linux-vdso
with a prior configure cmd like below with PATH pointing to the cross
compiler.
../configure --target-list=riscv64-linux-user
--cross-cc-riscv64=riscv64-unknown-linux-gnu-gcc
Yes, that should do it.
But it doesn't, I'm sure we are missing something basis here.
Do you get an error message?
Did $(BUILD_DIR)/tests/tcg/riscv64-linux-user/config-target.mak get created
properly?
For starters we saw something that seems like a thinko in
diff --git a/linux-user/riscv/vdso.S b/linux-user/riscv/vdso.S
-#define sizeof_reg (__riscv_xlen / 4)
+#define sizeof_reg (__riscv_xlen / 8)
Oops.
As as aside, we also see that rt_sigreturn in kernel vdso elides the
explicit the call frame information. Again we naively don't know if that
is required in qemu.
.text
ENTRY(__vdso_rt_sigreturn)
.cfi_startproc
.cfi_signal_frame
li a7, __NR_rt_sigreturn
ecall
.cfi_endproc
ENDPROC(__vdso_rt_sigreturn)
Perhaps it's not required, no. But I'd consider the lack of info from the kernel to be a
bug. Lack of it means places like gcc have to have special cases.
r~
