binder_alloc_get_page(9)

🦋 binder_alloc_get_page(9) — the Kernel API Manual glow-up 🦋

okay so this is a page from the Kernel API Manual (Linux kernel docs, we love her) and it's literally about grabbing a kernel pointer for a given buffer offset. no cap, that's the whole vibe. let's go 💅

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✨ NAME ✨

binder_alloc_get_page — get kernel pointer for given buffer offset

like… it gets you the pointer. for the offset. in the kernel. slay 🫶

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🌸 SYNOPSIS 🌸

struct page * binder_alloc_get_page (struct binder_alloc *alloc , struct
binder_buffer *buffer , binder_size_t buffer_offset , pgoff_t *pgoffp );

yes bestie that's four args, and yes you need all of them 😭

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🎀 ARGUMENTS 🎀

• alloc — the binder_alloc for this proc. it's giving "whose memory are we even talking about" energy ✨
• buffer — the binder buffer to be accessed. the main character of this whole operation ngl 👑
• buffer_offset — offset into buffer data. where inside the buffer you're pointing at 📍
• pgoffp — address to copy final page offset to. it's the out-param, it's lowkey the messenger 🧚

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💖 DESCRIPTION 💖

so what this does: it looks up the struct page corresponding to the address at buffer_offset into buffer->user_data. iconique behaviour honestly.

if pgoffp is not NULL, the byte-offset into the page gets written there. so it's not just a lookup, it's a lookup with a little gift for you on the side 🎁

⚠️ okay this part is mad important, do not skip it: the caller is responsible for making sure the offset points to a valid address within the buffer, and that buffer is not freeable by the user. like, that's on YOU, bestie, not on this function 🙈

and the reasoning behind the whole rule, because it's actually so clean: since it can't be freed, we are guaranteed that the corresponding elements of alloc->pages[] cannot change. stable. consistent. periodt 💀✨

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⭐ RETURN ⭐

struct page — that's it, that's the return. a struct page. no drama 🔥

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/android/binder_alloc.c
• binder_alloc_prepare_to_free(9)
• binder_alloc_new_buf(9)
• binder_alloc_clear_buf(9)
• binder_alloc_free_buf(9)
• binder_alloc_mmap_handler(9)
• binder_alloc_print_allocated(9)
• binder_alloc_print_pages(9)
• binder_alloc_get_allocated_count(9)
• binder_alloc_vma_close(9)
• binder_alloc_free_page(9)
• binder_alloc_init(9)
• check_buffer(9)
• binder_alloc_copy_user_to_buffer(9)

the whole binder_alloc friend group, we stan a supportive cast 🫶💜

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and that's the page!! brought to you by ./drivers/android, dated October 2026, titled binder_alloc_get_page(9) — see you in the next buffer offset bestie 💅🎀✨