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 <hbath...@linux.ibm.com> --- 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
