[PATCH v2 2/4] powerpc/bpf: implement bpf_arch_text_copy

[Hari Bathini <hbathini@linux.ibm.com>]

bpf_arch_text_copy is used to dump JITed binary to RX page, allowing
multiple BPF programs to share the same page. Use the newly introduced
patch_instructions() to implement it. Around 5X improvement in speed
of execution observed, using the new patch_instructions() function
over patch_instruction(), while running the tests from test_bpf.ko.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
 arch/powerpc/net/bpf_jit_comp.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index e93aefcfb83f..0a70319116d1 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -13,9 +13,12 @@
 #include <linux/netdevice.h>
 #include <linux/filter.h>
 #include <linux/if_vlan.h>
-#include <asm/kprobes.h>
+#include <linux/memory.h>
 #include <linux/bpf.h>
 
+#include <asm/kprobes.h>
+#include <asm/code-patching.h>
+
 #include "bpf_jit.h"
 
 static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
@@ -272,3 +275,21 @@ int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct code
 	ctx->exentry_idx++;
 	return 0;
 }
+
+void *bpf_arch_text_copy(void *dst, void *src, size_t len)
+{
+	void *ret = ERR_PTR(-EINVAL);
+	int err;
+
+	if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst)))
+		return ret;
+
+	ret = dst;
+	mutex_lock(&text_mutex);
+	err = patch_instructions(dst, src, false, len);
+	if (err)
+		ret = ERR_PTR(err);
+	mutex_unlock(&text_mutex);
+
+	return ret;
+}
-- 
2.39.2