Re: [PATCHv5 perf/core 08/22] uprobes/x86: Add mapping for optimized uprobe trampolines
From: Oleg Nesterov <oleg@redhat.com>
Date: 2025-07-11 17:47:38
Also in:
bpf, lkml
On 07/11, Jiri Olsa wrote:
+static unsigned long find_nearest_trampoline(unsigned long vaddr)
+{
+ struct vm_unmapped_area_info info = {
+ .length = PAGE_SIZE,
+ .align_mask = ~PAGE_MASK,
+ };
+ unsigned long low_limit, high_limit;
+ unsigned long low_tramp, high_tramp;
+ unsigned long call_end = vaddr + 5;
+
+ if (check_add_overflow(call_end, INT_MIN, &low_limit))
+ low_limit = PAGE_SIZE;
+
+ high_limit = call_end + INT_MAX;
+
+ /* Search up from the caller address. */
+ info.low_limit = call_end;
+ info.high_limit = min(high_limit, TASK_SIZE);
+ high_tramp = vm_unmapped_area(&info);
+
+ /* Search down from the caller address. */
+ info.low_limit = max(low_limit, PAGE_SIZE);
+ info.high_limit = call_end;
+ info.flags = VM_UNMAPPED_AREA_TOPDOWN;
+ low_tramp = vm_unmapped_area(&info);
+
+ if (IS_ERR_VALUE(high_tramp) && IS_ERR_VALUE(low_tramp))
+ return -ENOMEM;
+ if (IS_ERR_VALUE(high_tramp))
+ return low_tramp;
+ if (IS_ERR_VALUE(low_tramp))
+ return high_tramp;
+
+ /* Return address that's closest to the caller address. */
+ if (call_end - low_tramp < high_tramp - call_end)
+ return low_tramp;
+ return high_tramp;
+}IIUC, nothing else has changed since I've acked the previous version? Then my ack still stands, Acked-by: Oleg Nesterov <oleg@redhat.com>