On 5/10/2022 7:45 PM, Jakub Sitnicki wrote:
On Sun, Apr 24, 2022 at 11:40 AM -04, Xu Kuohai wrote:
Impelment bpf_arch_text_poke() for arm64, so bpf trampoline code can use it to replace nop with jump, or replace jump with nop.
Signed-off-by: Xu Kuohai xukuohai@huawei.com Acked-by: Song Liu songliubraving@fb.com
arch/arm64/net/bpf_jit_comp.c | 63 +++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 8ab4035dea27..3f9bdfec54c4 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -9,6 +9,7 @@ #include <linux/bitfield.h> #include <linux/bpf.h> +#include <linux/memory.h> #include <linux/filter.h> #include <linux/printk.h> #include <linux/slab.h> @@ -18,6 +19,7 @@ #include <asm/cacheflush.h> #include <asm/debug-monitors.h> #include <asm/insn.h> +#include <asm/patching.h> #include <asm/set_memory.h> #include "bpf_jit.h" @@ -1529,3 +1531,64 @@ void bpf_jit_free_exec(void *addr) { return vfree(addr); }
+static int gen_branch_or_nop(enum aarch64_insn_branch_type type, void *ip,
void *addr, u32 *insn)+{
- if (!addr)
*insn = aarch64_insn_gen_nop();- else
*insn = aarch64_insn_gen_branch_imm((unsigned long)ip,(unsigned long)addr,type);- return *insn != AARCH64_BREAK_FAULT ? 0 : -EFAULT;
+}
+int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type poke_type,
void *old_addr, void *new_addr)+{
- int ret;
- u32 old_insn;
- u32 new_insn;
- u32 replaced;
- enum aarch64_insn_branch_type branch_type;
- if (!is_bpf_text_address((long)ip))
/* Only poking bpf text is supported. Since kernel function* entry is set up by ftrace, we reply on ftrace to poke kernel* functions. For kernel funcitons, bpf_arch_text_poke() is onlyNit: s/funcitons/functions/
* called after a failed poke with ftrace. In this case, there* is probably something wrong with fentry, so there is nothing* we can do here. See register_fentry, unregister_fentry and* modify_fentry for details.*/return -EINVAL;- if (poke_type == BPF_MOD_CALL)
branch_type = AARCH64_INSN_BRANCH_LINK;- else
branch_type = AARCH64_INSN_BRANCH_NOLINK;- if (gen_branch_or_nop(branch_type, ip, old_addr, &old_insn) < 0)
return -EFAULT;- if (gen_branch_or_nop(branch_type, ip, new_addr, &new_insn) < 0)
return -EFAULT;- mutex_lock(&text_mutex);
- if (aarch64_insn_read(ip, &replaced)) {
ret = -EFAULT;goto out;- }
- if (replaced != old_insn) {
ret = -EFAULT;goto out;- }
- ret = aarch64_insn_patch_text_nosync((void *)ip, new_insn);
Nit: No need for the explicit cast to void *. Type already matches.
+out:
- mutex_unlock(&text_mutex);
- return ret;
+}
.
will fix in v4, thanks!