diff options
| author | Russell King <russell.king@oracle.com> | 2021-11-05 16:50:45 +0000 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-11-08 22:16:26 +0100 |
| commit | b89ddf4cca43f1269093942cf5c4e457fd45c335 (patch) | |
| tree | d8f7c34876d83786477b7ae84adbc8b1d0b3eaa3 /arch/arm64/kernel/traps.c | |
| parent | 0cc78dcca36de43f6ec4a94ddf64ddfa9bb36024 (diff) | |
arm64/bpf: Remove 128MB limit for BPF JIT programs
Commit 91fc957c9b1d ("arm64/bpf: don't allocate BPF JIT programs in module
memory") restricts BPF JIT program allocation to a 128MB region to ensure
BPF programs are still in branching range of each other. However this
restriction should not apply to the aarch64 JIT, since BPF_JMP | BPF_CALL
are implemented as a 64-bit move into a register and then a BLR instruction -
which has the effect of being able to call anything without proximity
limitation.
The practical reason to relax this restriction on JIT memory is that 128MB of
JIT memory can be quickly exhausted, especially where PAGE_SIZE is 64KB - one
page is needed per program. In cases where seccomp filters are applied to
multiple VMs on VM launch - such filters are classic BPF but converted to
BPF - this can severely limit the number of VMs that can be launched. In a
world where we support BPF JIT always on, turning off the JIT isn't always an
option either.
Fixes: 91fc957c9b1d ("arm64/bpf: don't allocate BPF JIT programs in module memory")
Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <russell.king@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/1636131046-5982-2-git-send-email-alan.maguire@oracle.com
Diffstat (limited to 'arch/arm64/kernel/traps.c')
| -rw-r--r-- | arch/arm64/kernel/traps.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 7b21213a570f..e8986e6067a9 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -994,7 +994,7 @@ static struct break_hook bug_break_hook = { static int reserved_fault_handler(struct pt_regs *regs, unsigned int esr) { pr_err("%s generated an invalid instruction at %pS!\n", - in_bpf_jit(regs) ? "BPF JIT" : "Kernel text patching", + "Kernel text patching", (void *)instruction_pointer(regs)); /* We cannot handle this */ |