[RFC] arm64: extra entries in /proc/iomem for kexec
AKASHI Takahiro
takahiro.akashi at linaro.org
Wed Mar 14 01:29:42 PDT 2018
In the last couples of months, there were some problems reported [1],[2]
around arm64 kexec/kdump. Where those phenomenon look different,
the root cause would be that kexec/kdump doesn't take into account
crucial "reserved" regions of system memory and unintentionally corrupts
them.
Given that kexec-tools looks for all the information by seeking the file,
/proc/iomem, the first step to address said problems is to expand this file's
format so that it will have enough information about system memory and
its usage.
Attached is my experimental code: With this patch applied, /proc/iomem sees
something like the below:
(format A)
40000000-5871ffff : System RAM
40080000-40f1ffff : Kernel code
41040000-411e8fff : Kernel data
54400000-583fffff : Crash kernel
58590000-585effff : EFI Resources
58700000-5871ffff : EFI Resources
58720000-58b5ffff : System RAM
58720000-58b5ffff : EFI Resources
58b60000-5be3ffff : System RAM
58b61018-58b61947 : EFI Memory Map
59a7b118-59a7b667 : EFI Configuration Tables
5be40000-5becffff : System RAM <== (A-1)
5be40000-5becffff : EFI Resources
5bed0000-5bedffff : System RAM
5bee0000-5bffffff : System RAM
5bee0000-5bffffff : EFI Resources
5c000000-5fffffff : System RAM
8000000000-ffffffffff : PCI Bus 0000:00
Meanwhile, the workaround I suggested in [3] gave us a simpler view:
(format B)
40000000-5871ffff : System RAM
40080000-40f1ffff : Kernel code
41040000-411e9fff : Kernel data
54400000-583fffff : Crash kernel
58590000-585effff : reserved
58700000-5871ffff : reserved
58720000-58b5ffff : reserved
58b60000-5be3ffff : System RAM
58b61000-58b61fff : reserved
59a7b318-59a7b867 : reserved
5be40000-5becffff : reserved <== (B-1)
5bed0000-5bedffff : System RAM
5bee0000-5bffffff : reserved
5c000000-5fffffff : System RAM
5ec00000-5edfffff : reserved
8000000000-ffffffffff : PCI Bus 0000:00
Here all the regions to be protected are named just "reserved" whether
they are NOMAP regions or simply-memblock_reserve'd. They are not very
useful for anything but kexec/kdump which knows what they mean.
Alternatively, we may want to give them more specific names, based on
related efi memory map descriptors and else, that will characterize
their contents:
(format C)
40000000-5871ffff : System RAM
40080000-40f1ffff : Kernel code
41040000-411e9fff : Kernel data
54400000-583fffff : Crash kernel
58590000-585effff : ACPI Reclaim Memory
58700000-5871ffff : ACPI Reclaim Memory
58720000-58b5ffff : System RAM
58720000-5878ffff : Runtime Data
58790000-587dffff : Runtime Code
587e0000-5882ffff : Runtime Data
58830000-5887ffff : Runtime Code
58880000-588cffff : Runtime Data
588d0000-5891ffff : Runtime Code
58920000-5896ffff : Runtime Data
58970000-589bffff : Runtime Code
589c0000-58a5ffff : Runtime Data
58a60000-58abffff : Runtime Code
58ac0000-58b0ffff : Runtime Data
58b10000-58b5ffff : Runtime Code
58b60000-5be3ffff : System RAM
58b61000-58b61fff : EFI Memory Map
59a7b118-59a7b667 : EFI Memory Attributes Table
5be40000-5becffff : System RAM
5be40000-5becffff : Runtime Code
5bed0000-5bedffff : System RAM
5bee0000-5bffffff : System RAM
5bee0000-5bffffff : Runtime Data
5c000000-5fffffff : System RAM
8000000000-ffffffffff : PCI Bus 0000:00
I once created a patch for this format, but it looks quite noisy and
names are a sort of mixture of memory attributes( ACPI Reclaim memory,
Conventional Memory, Persistent Memory etc.) vs.
function/usages ([Loader|Boot Service|Runtime] Code/Data).
(As a matter of fact, (C-1) consists of various ACPI tables.)
Anyhow, they seem not so useful for most of other applications.
Those observations lead to format A, where some entries with the same
attributes are squeezed into a single entry under a simple name if they
are neighbouring.
So my questions here are:
1. Which format, A, B, or C, is the most appropriate for the moment?
or any other suggestions?
Currently, there is a inconsistent view between (A) and the mainline's:
see (A-1) and (B-1). If this is really a matter, I can fix it.
Kexec-tools can be easily modified to accept both formats, though.
2. How should we determine which regions be exported in /proc/iomem?
a. Trust all the memblock_reserve'd regions as my previous patch [3] does.
As I said, it's a kind of "overkill." Some of regions, say fdt, are
not required to be preserved across kexec.
b. List regions separately and exhaustively later on at a single point
as my patch attached does.
I'm afraid of any possibility that some regions may be doubly counted,
one from efi memory map search and another from other efi/acpi code
(various type of "tables" in most cases).
c. Expand efi_mem_reserve() with an argument of "resource descriptor" and
replace memblock_reserve() in efi code wherever necessary so as to
maintain an export list.
efi_mem_reserve() was first introduced for specific needs at kexec
on x86, but I believe that its coverage over efi code is far from perfect.
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2017-November/541831.html
[2] http://lkml.iu.edu//hypermail/linux/kernel/1802.2/06745.html
[3] http://lkml.iu.edu//hypermail/linux/kernel/1803.0/04658.html
http://lkml.iu.edu//hypermail/linux/kernel/1803.0/04659.html
-Takahiro AKASHI
===8<===
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 30ad2f085d1f..feda5cbdc6bf 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -214,13 +214,8 @@ static void __init request_standard_resources(void)
for_each_memblock(memory, region) {
res = alloc_bootmem_low(sizeof(*res));
- if (memblock_is_nomap(region)) {
- res->name = "reserved";
- res->flags = IORESOURCE_MEM;
- } else {
- res->name = "System RAM";
- res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
- }
+ res->name = "System RAM";
+ res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
res->start = __pfn_to_phys(memblock_region_memory_base_pfn(region));
res->end = __pfn_to_phys(memblock_region_memory_end_pfn(region)) - 1;
@@ -239,6 +234,9 @@ static void __init request_standard_resources(void)
request_resource(res, &crashk_res);
#endif
}
+
+ /* Add firmware-reserved memory */
+ efi_arch_request_resources();
}
u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index 80d1a885def5..308143e69db4 100644
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -13,8 +13,10 @@
#define pr_fmt(fmt) "efi: " fmt
+#include <linux/bootmem.h>
#include <linux/efi.h>
#include <linux/init.h>
+#include <linux/ioport.h>
#include <linux/memblock.h>
#include <linux/mm_types.h>
#include <linux/of.h>
@@ -280,3 +282,97 @@ static int __init register_gop_device(void)
return PTR_ERR_OR_ZERO(pd);
}
subsys_initcall(register_gop_device);
+
+static unsigned long __init efi_memattr_to_iores_type(u64 addr)
+{
+ if (efi_mem_attributes(addr) &
+ (EFI_MEMORY_WB|EFI_MEMORY_WT|EFI_MEMORY_WC))
+ return IORESOURCE_SYSTEM_RAM;
+ else
+ return IORESOURCE_MEM;
+}
+
+static unsigned long __init efi_type_to_iores_desc(u64 addr)
+{
+ /* TODO */
+ return IORES_DESC_NONE;
+}
+
+static struct resource * __init _efi_arch_request_resource(u64 start, u64 end,
+ char *name, struct resource *prev)
+{
+ struct resource *conflict, *res;
+
+ res = alloc_bootmem_low(sizeof(*res));
+
+ res->start = start;
+ res->end = end;
+ res->flags = efi_memattr_to_iores_type(res->start);
+ res->desc = efi_type_to_iores_desc(res->start);
+ res->name = name;
+
+ conflict = request_resource_conflict(&iomem_resource, res);
+ if (conflict) {
+ if (prev && (prev->parent == conflict) &&
+ ((prev->end + 1) == start)) {
+ /* merge consecutive regions */
+ adjust_resource(prev, prev->start,
+ end - prev->start + 1);
+ free_bootmem((unsigned long)res, sizeof(*res));
+ res = prev;
+ } else
+ insert_resource(conflict, res);
+ }
+
+ return res;
+}
+
+/* Kexec expects those resources to be preserved */
+void __init efi_arch_request_resources(void)
+{
+ struct resource *res = NULL;
+ efi_memory_desc_t *md;
+ u64 paddr, npages, size;
+
+ /* EFI Memory Map */
+ /* FIXME */
+ _efi_arch_request_resource(efi.memmap.phys_map,
+ efi.memmap.phys_map
+ + efi.memmap.desc_size * efi.memmap.nr_map - 1,
+ "EFI Memory Map", res);
+
+ /* generic EFI Configuration Tables */
+ efi_request_config_table_resources(_efi_arch_request_resource);
+
+ /* architecture-specifc Configuration Tables */
+ if (screen_info.lfb_size)
+ _efi_arch_request_resource(screen_info.lfb_base,
+ screen_info.lfb_base + screen_info.lfb_size - 1,
+ "EFI Screen Info Table", res);
+
+ /* architecture-specific EFI resources */
+ /* FIXME */
+ efi_memmap_install(efi.memmap.phys_map, efi.memmap.nr_map);
+
+ res = NULL;
+ for_each_efi_memory_desc(md) {
+ paddr = md->phys_addr;
+ npages = md->num_pages;
+
+ memrange_efi_to_native(&paddr, &npages);
+ size = npages << PAGE_SHIFT;
+
+ if (is_memory(md)) {
+ if (!is_usable_memory(md))
+ res = _efi_arch_request_resource(paddr,
+ paddr + size - 1,
+ "EFI Resources", res);
+
+ if (md->type == EFI_ACPI_RECLAIM_MEMORY)
+ res = _efi_arch_request_resource(paddr,
+ paddr + size - 1,
+ "EFI Resources", res);
+ }
+ }
+ efi_memmap_unmap();
+}
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index cd42f66a7c85..b13c9461278b 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -603,6 +603,33 @@ int __init efi_config_init(efi_config_table_type_t *arch_tables)
return ret;
}
+void __init efi_request_config_table_resources(struct resource *(*fn)(u64 start,
+ u64 end, char *name, struct resource *prev))
+{
+ struct resource *prev = NULL;
+ char *name = "EFI Configuration Tables";
+
+ if (efi.config_table_size)
+ prev = fn(efi.config_table,
+ efi.config_table + efi.config_table_size - 1, name,
+ prev);
+
+ if (efi.mem_attr_table_size)
+ prev = fn(efi.mem_attr_table,
+ efi.mem_attr_table + efi.mem_attr_table_size - 1, name,
+ prev);
+
+ if (efi.esrt_size)
+ prev = fn(efi.esrt, efi.esrt + efi.esrt_size - 1, name, prev);
+
+ if (efi.tpm_log_size)
+ prev = fn(efi.tpm_log, efi.tpm_log + efi.tpm_log_size - 1, name,
+ prev);
+
+
+ /* TODO: BGRT */
+}
+
#ifdef CONFIG_EFI_VARS_MODULE
static int __init efi_load_efivars(void)
{
diff --git a/drivers/firmware/efi/esrt.c b/drivers/firmware/efi/esrt.c
index c47e0c6ec00f..61f66c139afb 100644
--- a/drivers/firmware/efi/esrt.c
+++ b/drivers/firmware/efi/esrt.c
@@ -330,6 +330,7 @@ void __init efi_esrt_init(void)
esrt_data = (phys_addr_t)efi.esrt;
esrt_data_size = size;
+ efi.esrt_size = size;
end = esrt_data + size;
pr_info("Reserving ESRT space from %pa to %pa.\n", &esrt_data, &end);
diff --git a/drivers/firmware/efi/memattr.c b/drivers/firmware/efi/memattr.c
index 8986757eafaf..dc2c7608793a 100644
--- a/drivers/firmware/efi/memattr.c
+++ b/drivers/firmware/efi/memattr.c
@@ -42,6 +42,7 @@ int __init efi_memattr_init(void)
}
tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size;
+ efi.mem_attr_table_size = tbl_size;
memblock_reserve(efi.mem_attr_table, tbl_size);
set_bit(EFI_MEM_ATTR, &efi.flags);
diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
index 0cbeb3d46b18..53cfb12513fa 100644
--- a/drivers/firmware/efi/tpm.c
+++ b/drivers/firmware/efi/tpm.c
@@ -33,6 +33,7 @@ int __init efi_tpm_eventlog_init(void)
}
tbl_size = sizeof(*log_tbl) + log_tbl->size;
+ efi.tpm_log_size = tbl_size;
memblock_reserve(efi.tpm_log, tbl_size);
early_memunmap(log_tbl, sizeof(*log_tbl));
return 0;
diff --git a/include/linux/efi.h b/include/linux/efi.h
index f5083aa72eae..9c3f8d284b36 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -942,11 +942,15 @@ extern struct efi {
unsigned long fw_vendor; /* fw_vendor */
unsigned long runtime; /* runtime table */
unsigned long config_table; /* config tables */
+ unsigned long config_table_size;
unsigned long esrt; /* ESRT table */
+ unsigned long esrt_size;
unsigned long properties_table; /* properties table */
unsigned long mem_attr_table; /* memory attributes table */
+ unsigned long mem_attr_table_size;
unsigned long rng_seed; /* UEFI firmware random seed */
unsigned long tpm_log; /* TPM2 Event Log table */
+ unsigned long tpm_log_size;
efi_get_time_t *get_time;
efi_set_time_t *set_time;
efi_get_wakeup_time_t *get_wakeup_time;
@@ -980,6 +984,9 @@ efi_guid_to_str(efi_guid_t *guid, char *out)
}
extern void efi_init (void);
+extern void efi_arch_request_resources(void);
+extern void efi_request_config_table_resources(struct resource *
+ (*fn)(u64 start, u64 end, char *name, struct resource *prev));
extern void *efi_get_pal_addr (void);
extern void efi_map_pal_code (void);
extern void efi_memmap_walk (efi_freemem_callback_t callback, void *arg);
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