From: Ard Biesheuvel <ardb+git@google.com>
To: linux-kernel@vger.kernel.org
Cc: linux-efi@vger.kernel.org, x86@kernel.org,
Ard Biesheuvel <ardb@kernel.org>,
"Mike Rapoport (Microsoft)" <rppt@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: [PATCH v2 08/19] x86/efi: Omit redundant kernel image overlap check
Date: Thu, 19 Mar 2026 10:05:38 +0100 [thread overview]
Message-ID: <20260319090529.1091660-29-ardb+git@google.com> (raw)
In-Reply-To: <20260319090529.1091660-21-ardb+git@google.com>
From: Ard Biesheuvel <ardb@kernel.org>
The physical region covering the kernel's executable image is
memblock_reserve()'d in early_mem_reserve(), and so it is guaranteed not
to intersect with the regions passed to can_free_region(). So remove the
pointless overlap check.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/x86/platform/efi/quirks.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index c867153eab8a..13d9e036a23a 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -305,16 +305,11 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
* can free regions in efi_free_boot_services().
*
* Use this function to ensure we do not free regions owned by somebody
- * else. We must only reserve (and then free) regions:
- *
- * - Not within any part of the kernel
- * - Not the BIOS reserved area (E820_TYPE_RESERVED, E820_TYPE_NVS, etc)
+ * else. We must only reserve (and then free) regions that do not intersect
+ * with the BIOS reserved area (E820_TYPE_RESERVED, E820_TYPE_NVS, etc)
*/
static __init bool can_free_region(u64 start, u64 size)
{
- if (start + size > __pa_symbol(_text) && start <= __pa_symbol(_end))
- return false;
-
if (!e820__mapped_all(start, start+size, E820_TYPE_RAM))
return false;
@@ -347,10 +342,8 @@ void __init efi_reserve_boot_services(void)
* Because the following memblock_reserve() is paired
* with free_reserved_area() for this region in
* efi_free_boot_services(), we must be extremely
- * careful not to reserve, and subsequently free,
- * critical regions of memory (like the kernel image) or
- * those regions that somebody else has already
- * reserved.
+ * careful not to reserve, and subsequently free, critical
+ * regions of memory that somebody else has already reserved.
*
* A good example of a critical region that must not be
* freed is page zero (first 4Kb of memory), which may
--
2.53.0.851.ga537e3e6e9-goog
next prev parent reply other threads:[~2026-03-19 9:06 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-19 9:05 [PATCH v2 00/19] efi/x86: Avoid the need to mangle the EFI memory map Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 01/19] memblock: Permit existing reserved regions to be marked RSRV_KERN Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 02/19] efi: Tag memblock reservations of boot services regions as RSRV_KERN Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 03/19] x86/efi: Unmap kernel-reserved boot regions from EFI page tables Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 04/19] x86/efi: Drop EFI_MEMORY_RUNTIME check from __ioremap_check_other() Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 05/19] x86/efi: Omit RSRV_KERN memblock reservations when freeing boot regions Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 06/19] x86/efi: Defer sub-1M check from unmap to free stage Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 07/19] x86/efi: Simplify real mode trampoline allocation quirk Ard Biesheuvel
2026-03-19 9:05 ` Ard Biesheuvel [this message]
2026-03-19 9:05 ` [PATCH v2 09/19] x86/efi: Drop redundant EFI_PARAVIRT check Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 10/19] x86/efi: Do not rely on EFI_MEMORY_RUNTIME bit and avoid entry splitting Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 11/19] efi: Use nr_map not map_end to find the last valid memory map entry Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 12/19] x86/efi: Only merge EFI memory map entries on 32-bit systems Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 13/19] x86/efi: Clean the memory map using iterator and filter API Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 14/19] x86/efi: Update the runtime map in place Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 15/19] x86/efi: Use iterator API when mapping EFI regions for runtime Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 16/19] x86/efi: Reuse memory map instead of reallocating it Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 17/19] x86/efi: Defer compaction of the EFI memory map Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 18/19] x86/efi: Do not abuse RUNTIME bit to mark boot regions as reserved Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 19/19] x86/efi: Free unused tail of the EFI memory map Ard Biesheuvel
2026-03-24 9:50 ` [PATCH v2 00/19] efi/x86: Avoid the need to mangle " Ard Biesheuvel
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