[PATCH] riscv: net: bpf: add bpf_jit_supports_private_stack()

[JaeJoon Jung <rgbi3307@gmail.com>]

The bpf_jit_supports_private_stack() function is defined with the __weak
attribute in kernel/bpf/core.c as shown below, and returns false.

include/linux/filter.h:1191:bool bpf_jit_supports_private_stack(void);
kernel/bpf/core.c:3381:bool __weak bpf_jit_supports_private_stack(void)

However, if this function is not defined in the corresponding architecture to
return true, an error occurs when loading BPF as follows, and it is not loaded.

$ cd tools/sched_ext
$ make
$ sudo ./build/bin/scx_simple

libbpf: prog 'simple_dispatch': BPF program load failed: -EACCES
libbpf: prog 'simple_dispatch': -- BEGIN PROG LOAD LOG --
Private stack not supported by jit

arm64, powerpc, and x86 are defined as follows and return true.

arch/arm64/net/bpf_jit_comp.c:2318:bool bpf_jit_supports_private_stack(void)
arch/powerpc/net/bpf_jit_comp.c:530:bool bpf_jit_supports_private_stack(void)
arch/x86/net/bpf_jit_comp.c:4111:bool bpf_jit_supports_private_stack(void)

It seems that it should be defined in the same way in RISCV as well.

Signed-off-by: JaeJoon Jung <rgbi3307@gmail.com>
---
 arch/riscv/net/bpf_jit_comp64.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 8fe8969fb8a0..c3e8d91836f1 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -2171,3 +2171,8 @@ bool bpf_jit_supports_timed_may_goto(void)
 {
 	return true;
 }
+
+bool bpf_jit_supports_private_stack(void)
+{
+        return true;
+}
--
2.43.0