get_seg_base_limit(9)

💅 get_seg_base_limit(9) — from the Kernel API Manual, bestie

okay so real talk, this is a kernel API manual page (get_seg_base_limit(9)) and honestly? it's a baddie. it does exactly one thing and does it with main character energy: it gets you the base address and limit of a segment. that's it. that's the vibe. ✨

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🌸 SYNOPSIS 🌸

int get_seg_base_limit (struct insn *insn , struct pt_regs *regs , int
regoff , unsigned long *base , unsigned long *limit );

like, five arguments, one int return, no cap. 🫶

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🎀 ARGUMENTS 🎀

• insn — the instruction. must be valid, okurrr? no invalid instructions allowed, that's the rule. 👑
• regs — the register values exactly as they looked when you entered kernel mode. like a little snapshot. 📸
• regoff — the operand offset, in pt_regs, that gets used to resolve the segment descriptor. it's giving "which operand are we talking about" energy. 💅
• base — out comes the obtained segment base. yay! 💖
• limit — out comes the obtained segment limit. also yay! 🌈

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✨ DESCRIPTION ✨

so what this function actually does: it obtains the base address and the limit of the segment associated with the operand regoff and, if any or allowed, the override prefixes in insn. lowkey does two jobs at once, multitasking queen. 🧚

and here's the part where it's not like its cousin: this function is different from insn_get_seg_base, because the latter does not resolve the segment associated with the instruction operand. so don't @ them, they're different functions with different jobs, iykyk. 🦋

also super important — if a limit is not needed (e.g., when running in long mode), limit can be NULL. fr fr, just pass NULL, it's fine. 😌

Return values, and listen closely:

• 0 on success. base and limit will contain the base address and of the resolved segment, respectively. 💀 (that's the original wording, I'm not fixing it, I'm just delivering it, slay)
• -EINVAL on error. 🙈

ngl, keep that -EINVAL in your heart — errors happen, and you gotta handle them. periodt.

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🔥 SEE ALSO 🔥

this is the part where the page just. lists. everyone. the whole group chat. and honestly? iconic. 🎀

Kernel file ./arch/x86/lib/insn-eval.c is is_string_insn(9), insn_has_rep_prefix(9), get_seg_reg_override_idx(9), check_seg_overrides(9), resolve_default_seg(9), resolve_seg_reg(9), get_segment_selector(9), get_reg_offset_16(9), get_desc(9), insn_get_seg_base(9), get_seg_limit(9), insn_get_code_seg_params(9), insn_get_modrm_rm_off(9), insn_get_modrm_reg_off(9), insn_get_modrm_reg_ptr(9), get_eff_addr_reg(9), get_eff_addr_modrm(9), get_eff_addr_modrm_16(9), get_eff_addr_sib(9), get_addr_ref_16(9), get_addr_ref_32(9), get_addr_ref_64(9), insn_get_addr_ref(9), insn_fetch_from_user(9), insn_fetch_from_user_inatomic(9), insn_decode_from_regs(9), insn_decode_mmio(9)

like yes that's a lot of friends, but they're all valid references and every single one of them belongs here. 🫶⭐

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okay bestie, that's the whole page!! 💜 the source is ./arch/x86/lib, the version stamp is October 2026, and this absolute gem of a manual entry is get_seg_base_limit(9) — go forth, resolve those segments, and slay. 🎀✨🔥