linux-kernel - [PATCH v7 bpf-next 5/8] bpf: bump iter seq size to support BTF representation of large data structures

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Message-Id: <1601292670-1616-6-git-send-email-alan.maguire@oracle.com>
Date:   Mon, 28 Sep 2020 12:31:07 +0100
From:   Alan Maguire <alan.maguire@...cle.com>
To:     ast@...nel.org, daniel@...earbox.net, andriin@...com, yhs@...com
Cc:     linux@...musvillemoes.dk, andriy.shevchenko@...ux.intel.com,
        pmladek@...e.com, kafai@...com, songliubraving@...com,
        john.fastabend@...il.com, kpsingh@...omium.org, shuah@...nel.org,
        rdna@...com, scott.branden@...adcom.com, quentin@...valent.com,
        cneirabustos@...il.com, jakub@...udflare.com, mingo@...hat.com,
        rostedt@...dmis.org, acme@...nel.org, bpf@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH v7 bpf-next 5/8] bpf: bump iter seq size to support BTF representation of large data structures

BPF iter size is limited to PAGE_SIZE; if we wish to display BTF-based
representations of larger kernel data structures such as task_struct,
this will be insufficient.

Suggested-by: Alexei Starovoitov <alexei.starovoitov@...il.com>
Signed-off-by: Alan Maguire <alan.maguire@...cle.com>
---
 kernel/bpf/bpf_iter.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index 30833bb..8f10e30 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -88,8 +88,8 @@ static ssize_t bpf_seq_read(struct file *file, char __user *buf, size_t size,
 	mutex_lock(&seq->lock);
 
 	if (!seq->buf) {
-		seq->size = PAGE_SIZE;
-		seq->buf = kmalloc(seq->size, GFP_KERNEL);
+		seq->size = PAGE_SIZE << 3;
+		seq->buf = kvmalloc(seq->size, GFP_KERNEL);
 		if (!seq->buf) {
 			err = -ENOMEM;
 			goto done;
-- 
1.8.3.1