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Date: Tue, 2 Mar 2021 12:04:05 +0200
From: Mike Rapoport <rppt@...nel.org>
To: x86@...nel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Baoquan He <bhe@...hat.com>, Borislav Petkov <bp@...en8.de>,
David Hildenbrand <david@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...nel.org>,
Mike Rapoport <rppt@...nel.org>,
Mike Rapoport <rppt@...ux.ibm.com>, Qian Cai <cai@....pw>,
Thomas Gleixner <tglx@...utronix.de>,
Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, Borislav Petkov <bp@...e.de>
Subject: [PATCH v3 1/2] x86/setup: consolidate early memory reservations
From: Mike Rapoport <rppt@...ux.ibm.com>
The early reservations of memory areas used by the firmware, bootloader,
kernel text and data are spread over setup_arch(). Moreover, some of them
happen *after* memblock allocations, e.g trim_platform_memory_ranges() and
trim_low_memory_range() are called after reserve_real_mode() that allocates
memory.
There was no corruption of these memory regions because memblock always
allocates memory either from the end of memory (in top-down mode) or above
the kernel image (in bottom-up mode). However, the bottom up mode is going
to be updated to span the entire memory [1] to avoid limitations caused by
KASLR.
Consolidate early memory reservations in a dedicated function to improve
robustness against future changes. Having the early reservations in one
place also makes it clearer what memory must be reserved before we allow
memblock allocations.
[1] https://lore.kernel.org/lkml/20201217201214.3414100-2-guro@fb.com
Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
Acked-by: Borislav Petkov <bp@...e.de>
---
arch/x86/kernel/setup.c | 92 ++++++++++++++++++++---------------------
1 file changed, 44 insertions(+), 48 deletions(-)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d883176ef2ce..3e3c6036b023 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -645,18 +645,6 @@ static void __init trim_snb_memory(void)
}
}
-/*
- * Here we put platform-specific memory range workarounds, i.e.
- * memory known to be corrupt or otherwise in need to be reserved on
- * specific platforms.
- *
- * If this gets used more widely it could use a real dispatch mechanism.
- */
-static void __init trim_platform_memory_ranges(void)
-{
- trim_snb_memory();
-}
-
static void __init trim_bios_range(void)
{
/*
@@ -729,7 +717,38 @@ static void __init trim_low_memory_range(void)
{
memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE));
}
-
+
+static void __init early_reserve_memory(void)
+{
+ /*
+ * Reserve the memory occupied by the kernel between _text and
+ * __end_of_kernel_reserve symbols. Any kernel sections after the
+ * __end_of_kernel_reserve symbol must be explicitly reserved with a
+ * separate memblock_reserve() or they will be discarded.
+ */
+ memblock_reserve(__pa_symbol(_text),
+ (unsigned long)__end_of_kernel_reserve - (unsigned long)_text);
+
+ /*
+ * Make sure page 0 is always reserved because on systems with
+ * L1TF its contents can be leaked to user processes.
+ */
+ memblock_reserve(0, PAGE_SIZE);
+
+ early_reserve_initrd();
+
+ if (efi_enabled(EFI_BOOT))
+ efi_memblock_x86_reserve_range();
+
+ memblock_x86_reserve_range_setup_data();
+
+ reserve_ibft_region();
+ reserve_bios_regions();
+
+ trim_snb_memory();
+ trim_low_memory_range();
+}
+
/*
* Dump out kernel offset information on panic.
*/
@@ -764,29 +783,6 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
void __init setup_arch(char **cmdline_p)
{
- /*
- * Reserve the memory occupied by the kernel between _text and
- * __end_of_kernel_reserve symbols. Any kernel sections after the
- * __end_of_kernel_reserve symbol must be explicitly reserved with a
- * separate memblock_reserve() or they will be discarded.
- */
- memblock_reserve(__pa_symbol(_text),
- (unsigned long)__end_of_kernel_reserve - (unsigned long)_text);
-
- /*
- * Make sure page 0 is always reserved because on systems with
- * L1TF its contents can be leaked to user processes.
- */
- memblock_reserve(0, PAGE_SIZE);
-
- early_reserve_initrd();
-
- /*
- * At this point everything still needed from the boot loader
- * or BIOS or kernel text should be early reserved or marked not
- * RAM in e820. All other memory is free game.
- */
-
#ifdef CONFIG_X86_32
memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
@@ -910,8 +906,18 @@ void __init setup_arch(char **cmdline_p)
parse_early_param();
- if (efi_enabled(EFI_BOOT))
- efi_memblock_x86_reserve_range();
+ /*
+ * Do some memory reservations *before* memory is added to
+ * memblock, so memblock allocations won't overwrite it.
+ * Do it after early param, so we could get (unlikely) panic from
+ * serial.
+ *
+ * After this point everything still needed from the boot loader or
+ * firmware or kernel text should be early reserved or marked not
+ * RAM in e820. All other memory is free game.
+ */
+ early_reserve_memory();
+
#ifdef CONFIG_MEMORY_HOTPLUG
/*
* Memory used by the kernel cannot be hot-removed because Linux
@@ -938,9 +944,6 @@ void __init setup_arch(char **cmdline_p)
x86_report_nx();
- /* after early param, so could get panic from serial */
- memblock_x86_reserve_range_setup_data();
-
if (acpi_mps_check()) {
#ifdef CONFIG_X86_LOCAL_APIC
disable_apic = 1;
@@ -1032,8 +1035,6 @@ void __init setup_arch(char **cmdline_p)
*/
find_smp_config();
- reserve_ibft_region();
-
early_alloc_pgt_buf();
/*
@@ -1054,8 +1055,6 @@ void __init setup_arch(char **cmdline_p)
*/
sev_setup_arch();
- reserve_bios_regions();
-
efi_fake_memmap();
efi_find_mirror();
efi_esrt_init();
@@ -1081,9 +1080,6 @@ void __init setup_arch(char **cmdline_p)
reserve_real_mode();
- trim_platform_memory_ranges();
- trim_low_memory_range();
-
init_mem_mapping();
idt_setup_early_pf();
--
2.28.0
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