[PATCH bpf-next v1 RESEND 2/5] x86/alternative: support vmalloc_exec() and vfree_exec()

[Song Liu <song@kernel.org>]

Implement arch_vcopy_exec() and arch_invalidate_exec() to support
vmalloc_exec.

arch_vcopy_exec() copies dynamic kernel text (such as BPF programs) to
RO+X memory region allocated by vmalloc_exec().

arch_invalidate_exec() fills memory with 0xcc after it is released by
vfree_exec().

Signed-off-by: Song Liu <song@kernel.org>
---
 arch/x86/kernel/alternative.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 5cadcea035e0..73d89774ace3 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1270,6 +1270,18 @@ void *text_poke_copy(void *addr, const void *opcode, size_t len)
 	return addr;
 }
 
+void *arch_vcopy_exec(void *dst, void *src, size_t len)
+{
+	if (text_poke_copy(dst, src, len) == NULL)
+		return ERR_PTR(-EINVAL);
+	return dst;
+}
+
+int arch_invalidate_exec(void *ptr, size_t len)
+{
+	return IS_ERR_OR_NULL(text_poke_set(ptr, 0xcc, len));
+}
+
 /**
  * text_poke_set - memset into (an unused part of) RX memory
  * @addr: address to modify
-- 
2.30.2