Instead of blindly allocating PAGE_SIZE for each trampoline, check the size
of the trampoline with arch_bpf_trampoline_size(). This size is saved in
bpf_tramp_image->size, and used for modmem charge/uncharge. The fallback
arch_alloc_bpf_trampoline() still allocates a whole page because we need to
use set_memory_* to protect the memory.
struct_ops trampoline still uses a whole page for multiple trampolines.
With this size check at caller (regular trampoline and struct_ops
trampoline), remove arch_bpf_trampoline_size() from
arch_prepare_bpf_trampoline() in archs.
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Tested-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> # on s390x
---
arch/arm64/net/bpf_jit_comp.c | 7 -----
arch/riscv/net/bpf_jit_comp64.c | 7 -----
include/linux/bpf.h | 1 +
kernel/bpf/bpf_struct_ops.c | 7 +++++
kernel/bpf/trampoline.c | 49 +++++++++++++++++++++------------
5 files changed, 39 insertions(+), 32 deletions(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index a6671253b7ed..8955da5c47cf 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -2079,13 +2079,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image,
if (nregs > 8)
return -ENOTSUPP;
- ret = arch_bpf_trampoline_size(m, flags, tlinks, func_addr);
- if (ret < 0)
- return ret;
-
- if (ret > ((long)image_end - (long)image))
- return -EFBIG;
-
jit_fill_hole(image, (unsigned int)(image_end - image));
ret = prepare_trampoline(&ctx, im, tlinks, func_addr, nregs, flags);
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 35747fafde57..58dc64dd94a8 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -1052,13 +1052,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image,
int ret;
struct rv_jit_context ctx;
- ret = arch_bpf_trampoline_size(im, m, flags, tlinks, func_addr);
- if (ret < 0)
- return ret;
-
- if (ret > (long)image_end - (long)image)
- return -EFBIG;
-
ctx.ninsns = 0;
/*
* The bpf_int_jit_compile() uses a RW buffer (ctx.insns) to write the
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2ed65b764aab..17bd3dbd2636 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1122,6 +1122,7 @@ enum bpf_tramp_prog_type {
struct bpf_tramp_image {
void *image;
+ int size;
struct bpf_ksym ksym;
struct percpu_ref pcref;
void *ip_after_call;
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index e9e95879bce2..4d53c53fc5aa 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -355,6 +355,7 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks,
void *image, void *image_end)
{
u32 flags;
+ int size;
tlinks[BPF_TRAMP_FENTRY].links[0] = link;
tlinks[BPF_TRAMP_FENTRY].nr_links = 1;
@@ -362,6 +363,12 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks,
* and it must be used alone.
*/
flags = model->ret_size > 0 ? BPF_TRAMP_F_RET_FENTRY_RET : 0;
+
+ size = arch_bpf_trampoline_size(model, flags, tlinks, NULL);
+ if (size < 0)
+ return size;
+ if (size > (unsigned long)image_end - (unsigned long)image)
+ return -E2BIG;
return arch_prepare_bpf_trampoline(NULL, image, image_end,
model, flags, tlinks, NULL);
}
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 285c5b7c1ea4..7c0535edab3f 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -254,8 +254,8 @@ bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_a
static void bpf_tramp_image_free(struct bpf_tramp_image *im)
{
bpf_image_ksym_del(&im->ksym);
- arch_free_bpf_trampoline(im->image, PAGE_SIZE);
- bpf_jit_uncharge_modmem(PAGE_SIZE);
+ arch_free_bpf_trampoline(im->image, im->size);
+ bpf_jit_uncharge_modmem(im->size);
percpu_ref_exit(&im->pcref);
kfree_rcu(im, rcu);
}
@@ -349,7 +349,7 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im)
call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks);
}
-static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key)
+static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, int size)
{
struct bpf_tramp_image *im;
struct bpf_ksym *ksym;
@@ -360,12 +360,13 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key)
if (!im)
goto out;
- err = bpf_jit_charge_modmem(PAGE_SIZE);
+ err = bpf_jit_charge_modmem(size);
if (err)
goto out_free_im;
+ im->size = size;
err = -ENOMEM;
- im->image = image = arch_alloc_bpf_trampoline(PAGE_SIZE);
+ im->image = image = arch_alloc_bpf_trampoline(size);
if (!image)
goto out_uncharge;
@@ -380,9 +381,9 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key)
return im;
out_free_image:
- arch_free_bpf_trampoline(im->image, PAGE_SIZE);
+ arch_free_bpf_trampoline(im->image, im->size);
out_uncharge:
- bpf_jit_uncharge_modmem(PAGE_SIZE);
+ bpf_jit_uncharge_modmem(size);
out_free_im:
kfree(im);
out:
@@ -395,7 +396,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
struct bpf_tramp_links *tlinks;
u32 orig_flags = tr->flags;
bool ip_arg = false;
- int err, total;
+ int err, total, size;
tlinks = bpf_trampoline_get_progs(tr, &total, &ip_arg);
if (IS_ERR(tlinks))
@@ -408,12 +409,6 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
goto out;
}
- im = bpf_tramp_image_alloc(tr->key);
- if (IS_ERR(im)) {
- err = PTR_ERR(im);
- goto out;
- }
-
/* clear all bits except SHARE_IPMODIFY and TAIL_CALL_CTX */
tr->flags &= (BPF_TRAMP_F_SHARE_IPMODIFY | BPF_TRAMP_F_TAIL_CALL_CTX);
@@ -437,13 +432,31 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
tr->flags |= BPF_TRAMP_F_ORIG_STACK;
#endif
- err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE,
+ size = arch_bpf_trampoline_size(&tr->func.model, tr->flags,
+ tlinks, tr->func.addr);
+ if (size < 0) {
+ err = size;
+ goto out;
+ }
+
+ if (size > PAGE_SIZE) {
+ err = -E2BIG;
+ goto out;
+ }
+
+ im = bpf_tramp_image_alloc(tr->key, size);
+ if (IS_ERR(im)) {
+ err = PTR_ERR(im);
+ goto out;
+ }
+
+ err = arch_prepare_bpf_trampoline(im, im->image, im->image + size,
&tr->func.model, tr->flags, tlinks,
tr->func.addr);
if (err < 0)
goto out_free;
- arch_protect_bpf_trampoline(im->image, PAGE_SIZE);
+ arch_protect_bpf_trampoline(im->image, im->size);
WARN_ON(tr->cur_image && total == 0);
if (tr->cur_image)
@@ -463,8 +476,8 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut
tr->fops->func = NULL;
tr->fops->trampoline = 0;
- /* reset im->image memory attr for arch_prepare_bpf_trampoline */
- arch_unprotect_bpf_trampoline(im->image, PAGE_SIZE);
+ /* free im memory and reallocate later */
+ bpf_tramp_image_free(im);
goto again;
}
#endif
--
2.34.1
