On 25/08/23 9:03 pm, Christophe Leroy wrote:
Le 25/08/2023 à 17:18, Hari Bathini a écrit :
Implement bpf_arch_text_invalidate and use it to fill unused part of
the bpf_prog_pack with trap instructions when a BPF program is freed.
Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
---
arch/powerpc/net/bpf_jit_comp.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c
index 170ebf8ac0f2..7cd4cf53d61c 100644
--- a/arch/powerpc/net/bpf_jit_comp.c
+++ b/arch/powerpc/net/bpf_jit_comp.c
@@ -30,7 +30,7 @@ static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
* Patch 'len' bytes of instructions from opcode to addr, one instruction
* at a time. Returns addr on success. ERR_PTR(-EINVAL), otherwise.
*/
-static void *bpf_patch_instructions(void *addr, void *opcode, size_t len)
+static void *bpf_patch_instructions(void *addr, void *opcode, size_t len, bool fill_insn)
It's a pitty that you have to modify in patch 2 a function you have
added in patch 1 of the same series. Can't you have it right from the
begining ?
{
while (len > 0) {
ppc_inst_t insn = ppc_inst_read(opcode);
@@ -41,7 +41,8 @@ static void *bpf_patch_instructions(void *addr, void *opcode, size_t len)
len -= ilen;
addr = addr + ilen;
- opcode = opcode + ilen;
+ if (!fill_insn)
+ opcode = opcode + ilen;
}
return addr;
@@ -307,7 +308,22 @@ void *bpf_arch_text_copy(void *dst, void *src, size_t len)
return ERR_PTR(-EINVAL);
mutex_lock(&text_mutex);
- ret = bpf_patch_instructions(dst, src, len);
+ ret = bpf_patch_instructions(dst, src, len, false);
+ mutex_unlock(&text_mutex);
+
+ return ret;
+}
+
+int bpf_arch_text_invalidate(void *dst, size_t len)
+{
+ u32 insn = BREAKPOINT_INSTRUCTION;
+ int ret;
+
+ if (WARN_ON_ONCE(core_kernel_text((unsigned long)dst)))
+ return -EINVAL;
+
+ mutex_lock(&text_mutex);
+ ret = IS_ERR(bpf_patch_instructions(dst, &insn, len, true));
Why IS_ERR ?
As far as I understand from the weak definition in kernel/bpf/core.c,
this function is supposed to return an error, not a bool.
My bad! Will fix that in the next revision.
- Hari
