[PATCH v2 1/4] powerpc64/bpf: Add support for instruction array

[adubey at linux.ibm.com]

From: Abhishek Dubey <adubey at linux.ibm.com>

On loading the BPF program, the verifier might adjust/omit some
instructions. The adjusted instruction offset is accounted in the
map containing original instruction -> xlated mapping. This patch
add ppc64 JIT support to additionally build the xlated->jitted
mapping for every instruction present in instruction array. This
change is needed to enable support for indirect jumps, added in a
subsequent patch.

Invoke bpf_prog_update_insn_ptrs() with offset pair of xlated_offset
and jited_offset. The offset mapping is already available, which is
being used for bpf_prog_fill_jited_linfo() and can be directly used
for bpf_prog_update_insn_ptrs() as well.

Additional details present at:

commit b4ce5923e780 ("bpf, x86: add new map type: instructions array")

Signed-off-by: Abhishek Dubey <adubey at linux.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 9ec5ab9b020e..620667c3400b 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -373,6 +373,16 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 			goto out_addrs;
 		}
 		bpf_prog_fill_jited_linfo(fp, addrs);
+		/*
+		 * On ABI V1, executable code starts after the function
+		 * descriptor, so adjust base accordingly.
+		 */
+#ifdef CONFIG_PPC64_ELF_ABI_V1
+		bpf_prog_update_insn_ptrs(fp, addrs,
+				(void *)fimage + FUNCTION_DESCR_SIZE);
+#else
+		bpf_prog_update_insn_ptrs(fp, addrs, fimage);
+#endif
 out_addrs:
 		if (!image && priv_stack_ptr) {
 			fp->aux->priv_stack_ptr = NULL;
-- 
2.52.0