Subject: [PATCH v5 bpf-next 3/7] bpf: use size instead of pages in bpf_binary_header

From: Song Liu <[email-masked]>
Date: Thu, 20 Jan 2022 11:13:01 -0800

From: Song Liu <[email-masked]>

This is necessary to charge sub page memory for the BPF program.

Signed-off-by: Song Liu <[email-masked]>
---
 include/linux/filter.h |  6 +++---
 kernel/bpf/core.c      | 11 +++++------
 2 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index d23e999dc032..5855eb474c62 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -548,7 +548,7 @@ struct sock_fprog_kern {
 #define BPF_IMAGE_ALIGNMENT 8
 
 struct bpf_binary_header {
-	u32 pages;
+	u32 size;
 	u8 image[] __aligned(BPF_IMAGE_ALIGNMENT);
 };
 
@@ -886,8 +886,8 @@ static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
 {
 	set_vm_flush_reset_perms(hdr);
-	set_memory_ro((unsigned long)hdr, hdr->pages);
-	set_memory_x((unsigned long)hdr, hdr->pages);
+	set_memory_ro((unsigned long)hdr, hdr->size >> PAGE_SHIFT);
+	set_memory_x((unsigned long)hdr, hdr->size >> PAGE_SHIFT);
 }
 
 static inline struct bpf_binary_header *
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index b9c6a426a7dd..f252d8529b0b 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -543,7 +543,7 @@ bpf_prog_ksym_set_addr(struct bpf_prog *prog)
 	WARN_ON_ONCE(!bpf_prog_ebpf_jited(prog));
 
 	prog->aux->ksym.start = (unsigned long) prog->bpf_func;
-	prog->aux->ksym.end   = addr + hdr->pages * PAGE_SIZE;
+	prog->aux->ksym.end   = addr + hdr->size;
 }
 
 static void
@@ -866,7 +866,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
 		     bpf_jit_fill_hole_t bpf_fill_ill_insns)
 {
 	struct bpf_binary_header *hdr;
-	u32 size, hole, start, pages;
+	u32 size, hole, start;
 
 	WARN_ON_ONCE(!is_power_of_2(alignment) ||
 		     alignment > BPF_IMAGE_ALIGNMENT);
@@ -876,7 +876,6 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
 	 * random section of illegal instructions.
 	 */
 	size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE);
-	pages = size / PAGE_SIZE;
 
 	if (bpf_jit_charge_modmem(size))
 		return NULL;
@@ -889,7 +888,7 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
 	/* Fill space with illegal/arch-dep instructions. */
 	bpf_fill_ill_insns(hdr, size);
 
-	hdr->pages = pages;
+	hdr->size = size;
 	hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)),
 		     PAGE_SIZE - sizeof(*hdr));
 	start = (get_random_int() % hole) & ~(alignment - 1);
@@ -902,10 +901,10 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
 
 void bpf_jit_binary_free(struct bpf_binary_header *hdr)
 {
-	u32 pages = hdr->pages;
+	u32 size = hdr->size;
 
 	bpf_jit_free_exec(hdr);
-	bpf_jit_uncharge_modmem(pages << PAGE_SHIFT);
+	bpf_jit_uncharge_modmem(size);
 }
 
 /* This symbol is only overridden by archs that have different
-- 
2.30.2