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x86/setup: Consolidate early memory reservations

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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 memblock
allocations are allowed.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Link: [1] https://lore.kernel.org/lkml/20201217201214.3414100-2-guro@fb.com
Link: https://lkml.kernel.org/r/20210302100406.22059-2-rppt@kernel.org
This commit is contained in:
Mike Rapoport 2021-03-02 12:04:05 +02:00 committed by Borislav Petkov
parent e14cfb3bdd
commit a799c2bd29
1 changed files with 44 additions and 48 deletions
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92
arch/x86/kernel/setup.c
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@ -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();