[PATCH v2 06/10] bpf: support loading ELF files from memory

[Marat Khalili <marat.khalili@huawei.com>]

Introduce new ELF origin RTE_BPF_ORIGIN_ELF_MEMORY allowing one to
specify data area containing ELF image.

Signed-off-by: Marat Khalili <marat.khalili@huawei.com>
---
 lib/bpf/bpf_impl.h     |  5 +++++
 lib/bpf/bpf_load.c     |  4 ++++
 lib/bpf/bpf_load_elf.c | 40 +++++++++++++++++++++++++++++++++++++++-
 lib/bpf/rte_bpf.h      |  6 ++++++
 4 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/lib/bpf/bpf_impl.h b/lib/bpf/bpf_impl.h
index 92d03583d9..14ad772d4b 100644
--- a/lib/bpf/bpf_impl.h
+++ b/lib/bpf/bpf_impl.h
@@ -27,6 +27,7 @@ struct __rte_bpf_load {
 	/* Loading ELF and applying relocations. */
 	int elf_fd;  /* ELF fd, must be negative (not zero) by default. */
 	void *elf;  /* Using void to avoid dependency on libelf. */
+	const char *elf_section;
 
 	/* Value we are going to return, if any. */
 	struct rte_bpf *bpf;
@@ -53,6 +54,10 @@ __rte_bpf_load_elf_cleanup(struct __rte_bpf_load *load);
 int
 __rte_bpf_load_elf_file(struct __rte_bpf_load *load);
 
+/* Open the ELF memory image. */
+int
+__rte_bpf_load_elf_memory(struct __rte_bpf_load *load);
+
 /* Get code from ELF and apply relocations to it. */
 int
 __rte_bpf_load_elf_code(struct __rte_bpf_load *load);
diff --git a/lib/bpf/bpf_load.c b/lib/bpf/bpf_load.c
index c3c49ac49b..b626f6c616 100644
--- a/lib/bpf/bpf_load.c
+++ b/lib/bpf/bpf_load.c
@@ -237,6 +237,10 @@ load_try(struct __rte_bpf_load *load, const struct rte_bpf_prm_ex *app_prm)
 		rc = rc < 0 ? rc : __rte_bpf_load_elf_file(load);
 		rc = rc < 0 ? rc : __rte_bpf_load_elf_code(load);
 		break;
+	case RTE_BPF_ORIGIN_ELF_MEMORY:
+		rc = rc < 0 ? rc : __rte_bpf_load_elf_memory(load);
+		rc = rc < 0 ? rc : __rte_bpf_load_elf_code(load);
+		break;
 	default:
 		rc = rc < 0 ? rc : -EINVAL;
 	}
diff --git a/lib/bpf/bpf_load_elf.c b/lib/bpf/bpf_load_elf.c
index 4ae7492351..80443cb63a 100644
--- a/lib/bpf/bpf_load_elf.c
+++ b/lib/bpf/bpf_load_elf.c
@@ -310,6 +310,36 @@ __rte_bpf_load_elf_file(struct __rte_bpf_load *load)
 		return -EINVAL;
 	}
 
+	load->elf_section = prm->elf_file.section;
+
+	return 0;
+}
+
+int
+__rte_bpf_load_elf_memory(struct __rte_bpf_load *load)
+{
+	const struct rte_bpf_prm_ex *const prm = &load->prm;
+
+	RTE_ASSERT(prm->origin == RTE_BPF_ORIGIN_ELF_MEMORY);
+
+	if (prm->elf_memory.data == NULL || prm->elf_memory.section == NULL)
+		return -EINVAL;
+
+	if (elf_version(EV_CURRENT) == EV_NONE)
+		return -ENOTSUP;
+
+	load->elf = elf_memory(
+		/* Cast away const, we are not going to modify the ELF image. */
+		(char *)(uintptr_t)prm->elf_memory.data, prm->elf_memory.size);
+	if (load->elf == NULL) {
+		const int rc = elf_errno();
+		RTE_BPF_LOG_FUNC_LINE(ERR, "error %d opening ELF image: %s",
+			rc, elf_errmsg(rc));
+		return -EINVAL;
+	}
+
+	load->elf_section = prm->elf_memory.section;
+
 	return 0;
 }
 
@@ -321,7 +351,7 @@ __rte_bpf_load_elf_code(struct __rte_bpf_load *load)
 	size_t sidx;
 	int rc;
 
-	rc = find_elf_code(load->elf, prm->elf_file.section, &sd, &sidx);
+	rc = find_elf_code(load->elf, load->elf_section, &sd, &sidx);
 	if (rc < 0)
 		return rc;
 
@@ -353,6 +383,14 @@ __rte_bpf_load_elf_file(struct __rte_bpf_load *load)
 	return -ENOTSUP;
 }
 
+int
+__rte_bpf_load_elf_memory(struct __rte_bpf_load *load)
+{
+	RTE_SET_USED(load);
+	RTE_BPF_LOG_FUNC_LINE(ERR, "not supported, rebuild with libelf installed");
+	return -ENOTSUP;
+}
+
 int
 __rte_bpf_load_elf_code(struct __rte_bpf_load *load)
 {
diff --git a/lib/bpf/rte_bpf.h b/lib/bpf/rte_bpf.h
index da2bdea7e0..413ccf0497 100644
--- a/lib/bpf/rte_bpf.h
+++ b/lib/bpf/rte_bpf.h
@@ -97,6 +97,7 @@ enum rte_bpf_origin {
 	RTE_BPF_ORIGIN_RAW,		/**< code loaded from raw array */
 	RTE_BPF_ORIGIN_CBPF,		/**< code converted from cbpf */
 	RTE_BPF_ORIGIN_ELF_FILE,	/**< code loaded from elf_file */
+	RTE_BPF_ORIGIN_ELF_MEMORY,	/**< code loaded from elf_memory */
 };
 
 struct bpf_insn;
@@ -127,6 +128,11 @@ struct rte_bpf_prm_ex {
 			const char *path;  /**< path to the ELF file */
 			const char *section;  /**< ELF section with the code */
 		} elf_file;
+		struct {
+			const void *data;  /**< pointer to the ELF image */
+			size_t size;  /**< size of the ELF image */
+			const char *section;  /**< ELF section with the code */
+		} elf_memory;
 	};
 
 	const struct rte_bpf_xsym *xsym;
-- 
2.43.0