[PATCH v8 bpf-next 2/9] bpf: use bytes instead of pages for bpf_jit_[charge|uncharge]_modmem

Song Liu
2022-02-01T06:31:09Z

From: Song Liu <songliubraving@fb.com>

This enables sub-page memory charge and allocation.

Signed-off-by: Song Liu <songliubraving@fb.com>
---
include/linux/bpf.h | 4 ++--
kernel/bpf/core.c | 17 ++++++++---------
kernel/bpf/trampoline.c | 6 +++---
3 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 6eb0b180d33b..366f88afd56b 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -846,8 +846,8 @@ void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym);
void bpf_image_ksym_del(struct bpf_ksym *ksym);
void bpf_ksym_add(struct bpf_ksym *ksym);
void bpf_ksym_del(struct bpf_ksym *ksym);
-int bpf_jit_charge_modmem(u32 pages);
-void bpf_jit_uncharge_modmem(u32 pages);
+int bpf_jit_charge_modmem(u32 size);
+void bpf_jit_uncharge_modmem(u32 size);
bool bpf_prog_has_trampoline(const struct bpf_prog *prog);
#else
static inline int bpf_trampoline_link_prog(struct bpf_prog *prog,
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 04a8d5bea552..6ca0550c4b24 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -833,12 +833,11 @@ static int __init bpf_jit_charge_init(void)
}
pure_initcall(bpf_jit_charge_init);

-int bpf_jit_charge_modmem(u32 pages)
+int bpf_jit_charge_modmem(u32 size)
{
- if (atomic_long_add_return(pages, &bpf_jit_current) >
- (bpf_jit_limit >> PAGE_SHIFT)) {
+ if (atomic_long_add_return(size, &bpf_jit_current) > bpf_jit_limit) {
if (!bpf_capable()) {
- atomic_long_sub(pages, &bpf_jit_current);
+ atomic_long_sub(size, &bpf_jit_current);
return -EPERM;
}
}
@@ -846,9 +845,9 @@ int bpf_jit_charge_modmem(u32 pages)
return 0;
}

-void bpf_jit_uncharge_modmem(u32 pages)
+void bpf_jit_uncharge_modmem(u32 size)
{
- atomic_long_sub(pages, &bpf_jit_current);
+ atomic_long_sub(size, &bpf_jit_current);
}

void *__weak bpf_jit_alloc_exec(unsigned long size)
@@ -879,11 +878,11 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE);
pages = size / PAGE_SIZE;

- if (bpf_jit_charge_modmem(pages))
+ if (bpf_jit_charge_modmem(size))
return NULL;
hdr = bpf_jit_alloc_exec(size);
if (!hdr) {
- bpf_jit_uncharge_modmem(pages);
+ bpf_jit_uncharge_modmem(size);
return NULL;
}

@@ -906,7 +905,7 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr)
u32 pages = hdr->pages;

bpf_jit_free_exec(hdr);
- bpf_jit_uncharge_modmem(pages);
+ bpf_jit_uncharge_modmem(pages << PAGE_SHIFT);
}

/* This symbol is only overridden by archs that have different
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 4b6974a195c1..e76a488c09c3 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -213,7 +213,7 @@ static void __bpf_tramp_image_put_deferred(struct work_struct *work)
im = container_of(work, struct bpf_tramp_image, work);
bpf_image_ksym_del(&im->ksym);
bpf_jit_free_exec(im->image);
- bpf_jit_uncharge_modmem(1);
+ bpf_jit_uncharge_modmem(PAGE_SIZE);
percpu_ref_exit(&im->pcref);
kfree_rcu(im, rcu);
}
@@ -310,7 +310,7 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx)
if (!im)
goto out;

- err = bpf_jit_charge_modmem(1);
+ err = bpf_jit_charge_modmem(PAGE_SIZE);
if (err)
goto out_free_im;

@@ -332,7 +332,7 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx)
out_free_image:
bpf_jit_free_exec(im->image);
out_uncharge:
- bpf_jit_uncharge_modmem(1);
+ bpf_jit_uncharge_modmem(PAGE_SIZE);
out_free_im:
kfree(im);
out:
--
2.30.2