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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: Ard Biesheuvel <ardb@kernel.org>,
	linux-kernel@vger.kernel.org,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Young <dyoung@redhat.com>,
	Saravana Kannan <saravanak@google.com>
Subject: [PATCH 12/13] efi: Fix efi_memmap_alloc() leaks
Date: Mon, 13 Jan 2020 18:22:44 +0100	[thread overview]
Message-ID: <20200113172245.27925-13-ardb@kernel.org> (raw)
In-Reply-To: <20200113172245.27925-1-ardb@kernel.org>

From: Dan Williams <dan.j.williams@intel.com>

With efi_fake_memmap() and efi_arch_mem_reserve() the efi table may be
updated and replaced multiple times. When that happens a previous
dynamically allocated efi memory map can be garbage collected. Use the
new EFI_MEMMAP_{SLAB,MEMBLOCK} flags to detect when a dynamically
allocated memory map is being replaced.

Debug statements in efi_memmap_free() reveal:

 efi: __efi_memmap_free:37: phys: 0x23ffdd580 size: 2688 flags: 0x2
 efi: __efi_memmap_free:37: phys: 0x9db00 size: 2640 flags: 0x2
 efi: __efi_memmap_free:37: phys: 0x9e580 size: 2640 flags: 0x2

...a savings of 7968 bytes on a qemu boot with 2 entries specified to
efi_fake_mem=.

[ ardb: added a comment to clarify that efi_memmap_free() does nothing when
        called from efi_clean_memmap(), i.e., with data->flags == 0x0 ]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/memmap.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
index 04dfa56b994b..501672166502 100644
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -29,6 +29,28 @@ static phys_addr_t __init __efi_memmap_alloc_late(unsigned long size)
 	return PFN_PHYS(page_to_pfn(p));
 }
 
+static void __init __efi_memmap_free(u64 phys, unsigned long size, unsigned long flags)
+{
+	if (flags & EFI_MEMMAP_MEMBLOCK) {
+		if (slab_is_available())
+			memblock_free_late(phys, size);
+		else
+			memblock_free(phys, size);
+	} else if (flags & EFI_MEMMAP_SLAB) {
+		struct page *p = pfn_to_page(PHYS_PFN(phys));
+		unsigned int order = get_order(size);
+
+		free_pages((unsigned long) page_address(p), order);
+	}
+}
+
+static void __init efi_memmap_free(void)
+{
+	__efi_memmap_free(efi.memmap.phys_map,
+			efi.memmap.desc_size * efi.memmap.nr_map,
+			efi.memmap.flags);
+}
+
 /**
  * efi_memmap_alloc - Allocate memory for the EFI memory map
  * @num_entries: Number of entries in the allocated map.
@@ -100,6 +122,9 @@ static int __init __efi_memmap_init(struct efi_memory_map_data *data)
 		return -ENOMEM;
 	}
 
+	/* NOP if data->flags & (EFI_MEMMAP_MEMBLOCK | EFI_MEMMAP_SLAB) == 0 */
+	efi_memmap_free();
+
 	map.phys_map = data->phys_map;
 	map.nr_map = data->size / data->desc_size;
 	map.map_end = map.map + data->size;
-- 
2.20.1


  parent reply	other threads:[~2020-01-13 17:23 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-13 17:22 [GIT PULL 00/13] More EFI updates for v5.6 Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 01/13] efi/libstub/x86: use const attribute for efi_is_64bit() Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 02/13] efi/libstub/x86: use mandatory 16-byte stack alignment in mixed mode Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 03/13] efi/libstub/x86: fix unused-variable warning Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 04/13] x86/mm: fix NX bit clearing issue in kernel_map_pages_in_pgd Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 05/13] efi/x86: don't map the entire kernel text RW for mixed mode Ard Biesheuvel
2020-04-08 10:42   ` Jiri Slaby
2020-04-08 10:47     ` Ard Biesheuvel
2020-04-08 10:51       ` Jiri Slaby
2020-04-09  7:51         ` Ard Biesheuvel
2020-04-09  8:06           ` Gary Lin
2020-04-09  8:10             ` Jiri Slaby
2020-04-09  8:19               ` Ard Biesheuvel
2020-04-09  8:34                 ` Jiri Slaby
2020-04-09  9:09                   ` Ard Biesheuvel
2020-04-09  9:45                     ` Ard Biesheuvel
2020-04-09 10:09                     ` Jiri Slaby
2020-04-09 10:45                       ` Ard Biesheuvel
2020-04-09 11:08                         ` Ard Biesheuvel
2020-04-09 11:25                           ` Ard Biesheuvel
2020-04-09 11:32                             ` Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 06/13] efi/x86: avoid RWX mappings for all of DRAM Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 07/13] efi/x86: limit EFI old memory map to SGI UV machines Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 08/13] efi/arm: defer probe of PCIe backed efifb on DT systems Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 09/13] efi: Fix comment for efi_mem_type() wrt absent physical addresses Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 10/13] efi: Add a flags parameter to efi_memory_map Ard Biesheuvel
2020-01-13 17:22 ` [PATCH 11/13] efi: Add tracking for dynamically allocated memmaps Ard Biesheuvel
2020-01-13 17:22 ` Ard Biesheuvel [this message]
2020-01-13 17:22 ` [PATCH 13/13] efi: Fix handling of multiple efi_fake_mem= entries Ard Biesheuvel
2020-01-20  8:25 ` [GIT PULL 00/13] More EFI updates for v5.6 Ingo Molnar
2020-01-20  8:45   ` Ard Biesheuvel
2020-01-22  7:03     ` Ingo Molnar

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