Re: [PATCHv8 bpf-next 3/9] uprobe: Add uretprobe syscall to speed up return probe
From: Nathan Chancellor <nathan@kernel.org>
Date: 2024-06-14 17:48:26
Also in:
bpf, linux-api, linux-trace-kernel, lkml, loongarch
Hi Jiri, On Tue, Jun 11, 2024 at 01:21:52PM +0200, Jiri Olsa wrote:
Adding uretprobe syscall instead of trap to speed up return probe.
...
quoted hunk ↗ jump to hunk
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 2c83ba776fc7..2816e65729ac 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c@@ -1474,11 +1474,20 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) return ret; } +void * __weak arch_uprobe_trampoline(unsigned long *psize) +{ + static uprobe_opcode_t insn = UPROBE_SWBP_INSN;
This change as commit ff474a78cef5 ("uprobe: Add uretprobe syscall to
speed up return probe") in -next causes the following build error for
ARCH=loongarch allmodconfig:
In file included from include/linux/uprobes.h:49,
from include/linux/mm_types.h:16,
from include/linux/mmzone.h:22,
from include/linux/gfp.h:7,
from include/linux/xarray.h:16,
from include/linux/list_lru.h:14,
from include/linux/fs.h:13,
from include/linux/highmem.h:5,
from kernel/events/uprobes.c:13:
kernel/events/uprobes.c: In function 'arch_uprobe_trampoline':
arch/loongarch/include/asm/uprobes.h:12:33: error: initializer element is not constant
12 | #define UPROBE_SWBP_INSN larch_insn_gen_break(BRK_UPROBE_BP)
| ^~~~~~~~~~~~~~~~~~~~
kernel/events/uprobes.c:1479:39: note: in expansion of macro 'UPROBE_SWBP_INSN'
1479 | static uprobe_opcode_t insn = UPROBE_SWBP_INSN;
| ^~~~~~~~~~~~~~~~
quoted hunk ↗ jump to hunk
+ *psize = UPROBE_SWBP_INSN_SIZE; + return &insn; +} + static struct xol_area *__create_xol_area(unsigned long vaddr) { struct mm_struct *mm = current->mm; - uprobe_opcode_t insn = UPROBE_SWBP_INSN; + unsigned long insns_size; struct xol_area *area; + void *insns; area = kmalloc(sizeof(*area), GFP_KERNEL); if (unlikely(!area))@@ -1502,7 +1511,8 @@ static struct xol_area *__create_xol_area(unsigned long vaddr) /* Reserve the 1st slot for get_trampoline_vaddr() */ set_bit(0, area->bitmap); atomic_set(&area->slot_count, 1); - arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); + insns = arch_uprobe_trampoline(&insns_size); + arch_uprobe_copy_ixol(area->pages[0], 0, insns, insns_size); if (!xol_add_vma(mm, area)) return area;@@ -1827,7 +1837,7 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags) * * Returns -1 in case the xol_area is not allocated. */ -static unsigned long get_trampoline_vaddr(void) +unsigned long uprobe_get_trampoline_vaddr(void) { struct xol_area *area; unsigned long trampoline_vaddr = -1;@@ -1878,7 +1888,7 @@ static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) if (!ri) return; - trampoline_vaddr = get_trampoline_vaddr(); + trampoline_vaddr = uprobe_get_trampoline_vaddr(); orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); if (orig_ret_vaddr == -1) goto fail;@@ -2123,7 +2133,7 @@ static struct return_instance *find_next_ret_chain(struct return_instance *ri) return ri; } -static void handle_trampoline(struct pt_regs *regs) +void uprobe_handle_trampoline(struct pt_regs *regs) { struct uprobe_task *utask; struct return_instance *ri, *next;@@ -2187,8 +2197,8 @@ static void handle_swbp(struct pt_regs *regs) int is_swbp; bp_vaddr = uprobe_get_swbp_addr(regs); - if (bp_vaddr == get_trampoline_vaddr()) - return handle_trampoline(regs); + if (bp_vaddr == uprobe_get_trampoline_vaddr()) + return uprobe_handle_trampoline(regs); uprobe = find_active_uprobe(bp_vaddr, &is_swbp); if (!uprobe) {-- 2.45.1
Cheers, Nathan