Messages in this thread | | | Date | Tue, 4 Jan 2022 11:35:59 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH v5] arm64: kprobe: Enable OPTPROBE for arm64 |
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Hi Jianhua,
On Mon, 3 Jan 2022 17:03:33 +0800 Jianhua Liu <jianhua.ljh@gmail.com> wrote:
> Hi Qi, > I have tested your patch on UNISOC s9863a. > Test case "kprobe_example & kretprobe_example" is OK. > > Two point: > 1. backtrace is not perfect. > optprobe_common does not saved frame pointer, > backtrace lacks two calls. > such as for dup_mm: lack copy_process-->dup_mm > dup_mm backtrace from your patch: > [ 832.387066] CPU: 0 PID: 296 Comm: sh Not tainted 5.16.0-rc5+ #8 > [ 832.387078] Hardware name: Spreadtrum SP9863A-1H10 Board (DT) > [ 832.387083] Call trace: > [ 832.387086] dump_backtrace+0x0/0x1e0 > [ 832.387103] show_stack+0x24/0x30 > [ 832.387112] dump_stack_lvl+0x68/0x84 > [ 832.387123] dump_stack+0x18/0x34 > [ 832.387131] handler_pre+0x40/0x50 [kprobe_example] > [ 832.387143] opt_pre_handler+0x84/0xc0 > [ 832.387154] optprobe_optimized_callback+0xec/0x164 > [ 832.387164] optprobe_common+0x70/0xc4 > [ 832.387173] kernel_clone+0x98/0x440 > [ 832.387182] __do_sys_clone+0x54/0x80 > [ 832.387191] __arm64_sys_clone+0x2c/0x40 > [ 832.387199] invoke_syscall+0x50/0x120 > [ 832.387208] el0_svc_common.constprop.0+0x4c/0xf4 > [ 832.387217] do_el0_svc+0x30/0x9c > [ 832.387225] el0_svc+0x20/0x60 > [ 832.387235] el0t_64_sync_handler+0xe8/0xf0 > [ 832.387242] el0t_64_sync+0x1a0/0x1a4 > > > dup_mm backtrace from other: > [ 173.352294] CPU: 6 PID: 309 Comm: sh Not tainted 5.16.0-rc5+ #19 > [ 173.352301] Hardware name: Spreadtrum SP9863A-1H10 Board (DT) > [ 173.352304] Call trace: > [ 173.352307] dump_backtrace+0x0/0x1d4 > [ 173.352319] show_stack+0x18/0x24 > [ 173.352326] dump_stack_lvl+0x68/0x84 > [ 173.352333] dump_stack+0x18/0x34 > [ 173.352338] handler_pre+0x38/0x48 [kprobe_example] > [ 173.352347] opt_pre_handler+0x74/0xb0 > [ 173.352354] optimized_callback+0x108/0x130 > [ 173.352361] optinsn_slot+0x258/0x1000 > [ 173.352366] dup_mm+0x4/0x4b0 > [ 173.352373] copy_process+0x1284/0x1360 > [ 173.352378] kernel_clone+0x5c/0x3c0 > [ 173.352384] __do_sys_clone+0x54/0x80 > [ 173.352390] __arm64_sys_clone+0x24/0x30 > [ 173.352396] invoke_syscall+0x48/0x114 > [ 173.352402] el0_svc_common.constprop.0+0x44/0xec > [ 173.352408] do_el0_svc+0x24/0x90 > [ 173.352413] el0_svc+0x20/0x60 > [ 173.352420] el0t_64_sync_handler+0xe8/0xf0 > [ 173.352427] el0t_64_sync+0x1a0/0x1a4
Is the second one with your patch?
> > 2. The reserve memory "OPT_SLOT_SIZE - PAGE_SIZE" is waste. > kernel/kprobe.c used only one PAGE_SIZE slot memory.
Good catch! Qi, can you make an array (or bit map) of usage flags and manage the reserved memory?
#define OPT_INSN_PAGES (OPT_SLOT_SIZE/PAGE_SIZE) static bool insn_page_in_use[OPT_INSN_PAGES];
void *alloc_optinsn_page(void) { int i;
for (i = 0; i < OPT_INSN_PAGES; i++) if (!insn_page_in_use[i]) goto found; return NULL; found: insn_page_in_use[i] = true; return (void *)((unsigned long)optinsn_slot + PAGE_SIZE * i); }
void free_optinsn_page(void *page) { unsigned long idx = (unsigned long)page - (unsigned long)optinsn_slot;
WARN_ONCE(idx & (PAGE_SIZE - 1)); idx >>= PAGE_SHIFT; if (WARN_ONCE(idx >= OPT_INSN_PAGES)) return; insn_page_in_use[idx] = false; }
Thank you,
-- Masami Hiramatsu <mhiramat@kernel.org>
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