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Date: Tue, 3 Mar 2015 07:48:50 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Tapasweni Pathak <tapaswenipathak@...il.com>
Cc: matt.fleming@...el.com, tglx@...utronix.de, mingo@...hat.com,
hpa@...or.com, x86@...nel.org, linux-efi@...r.kernel.org,
linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>
Subject: [PATCH] efi: Clean up the efi_call_phys_[prolog|epilog]()
save/restore interaction
Also clean up the save_pgd global variable while at it.
untested as well.
Thanks,
Ingo
==============>
>From 166625ceaef68fcbeee63adc63c02d75abcaf0db Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@...nel.org>
Date: Tue, 3 Mar 2015 07:42:48 +0100
Subject: [PATCH] efi: Clean up the efi_call_phys_[prolog|epilog]() save/restore interaction
Currently x86-64 efi_call_phys_prolog() saves into a global variable (save_pgd),
and efi_call_phys_epilog() restores the kernel pagetables from that global
variable.
Change this to a cleaner save/restore pattern where the saving function returns
the saved object and the restore function restores that.
Apply the same concept to the 32-bit code as well.
Plus this approach, as an added bonus, allows us to express the
!efi_enabled(EFI_OLD_MEMMAP) situation in a clean fashion as well,
via a 'NULL' return value.
Cc: Tapasweni Pathak <tapaswenipathak@...il.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
arch/x86/include/asm/efi.h | 6 ++++--
arch/x86/platform/efi/efi.c | 5 +++--
arch/x86/platform/efi/efi_32.c | 11 ++++++++---
arch/x86/platform/efi/efi_64.c | 26 ++++++++++++++++----------
4 files changed, 31 insertions(+), 17 deletions(-)
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 25bce45c6fc4..3738b138b843 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -2,6 +2,8 @@
#define _ASM_X86_EFI_H
#include <asm/i387.h>
+#include <asm/pgtable.h>
+
/*
* We map the EFI regions needed for runtime services non-contiguously,
* with preserved alignment on virtual addresses starting from -4G down
@@ -89,8 +91,8 @@ extern void __iomem *__init efi_ioremap(unsigned long addr, unsigned long size,
extern struct efi_scratch efi_scratch;
extern void __init efi_set_executable(efi_memory_desc_t *md, bool executable);
extern int __init efi_memblock_x86_reserve_range(void);
-extern void __init efi_call_phys_prolog(void);
-extern void __init efi_call_phys_epilog(void);
+extern pgd_t * __init efi_call_phys_prolog(void);
+extern void __init efi_call_phys_epilog(pgd_t *save_pgd);
extern void __init efi_unmap_memmap(void);
extern void __init efi_memory_uc(u64 addr, unsigned long size);
extern void __init efi_map_region(efi_memory_desc_t *md);
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 2490a15d18f1..aa5bd2b986c2 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -86,8 +86,9 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
{
efi_status_t status;
unsigned long flags;
+ pgd_t *save_pgd;
- efi_call_phys_prolog();
+ save_pgd = efi_call_phys_prolog();
/* Disable interrupts around EFI calls: */
local_irq_save(flags);
@@ -96,7 +97,7 @@ static efi_status_t __init phys_efi_set_virtual_address_map(
descriptor_version, virtual_map);
local_irq_restore(flags);
- efi_call_phys_epilog();
+ efi_call_phys_epilog(save_pgd);
return status;
}
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index abecc6e1dc90..ed5b67338294 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -56,19 +56,24 @@ void __init efi_map_region(efi_memory_desc_t *md)
void __init efi_map_region_fixed(efi_memory_desc_t *md) {}
void __init parse_efi_setup(u64 phys_addr, u32 data_len) {}
-void __init efi_call_phys_prolog(void)
+pgd_t * __init efi_call_phys_prolog(void)
{
struct desc_ptr gdt_descr;
+ pgd_t *save_pgd;
+ /* Current pgd is swapper_pg_dir, we'll restore it later: */
+ save_pgd = swapper_pg_dir;
load_cr3(initial_page_table);
__flush_tlb_all();
gdt_descr.address = __pa(get_cpu_gdt_table(0));
gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);
+
+ return save_pgd;
}
-void __init efi_call_phys_epilog(void)
+void __init efi_call_phys_epilog(pgd_t *save_pgd)
{
struct desc_ptr gdt_descr;
@@ -76,7 +81,7 @@ void __init efi_call_phys_epilog(void)
gdt_descr.size = GDT_SIZE - 1;
load_gdt(&gdt_descr);
- load_cr3(swapper_pg_dir);
+ load_cr3(save_pgd);
__flush_tlb_all();
}
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 427eb3540e5f..a0ac0f9c307f 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -41,8 +41,6 @@
#include <asm/realmode.h>
#include <asm/time.h>
-static pgd_t *save_pgd __initdata;
-
/*
* We allocate runtime services regions bottom-up, starting from -4G, i.e.
* 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
@@ -77,14 +75,16 @@ static void __init early_code_mapping_set_exec(int executable)
}
}
-void __init efi_call_phys_prolog(void)
+pgd_t * __init efi_call_phys_prolog(void)
{
unsigned long vaddress;
+ pgd_t *save_pgd;
+
int pgd;
int n_pgds;
if (!efi_enabled(EFI_OLD_MEMMAP))
- return;
+ return NULL;
early_code_mapping_set_exec(1);
@@ -97,22 +97,28 @@ void __init efi_call_phys_prolog(void)
set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), *pgd_offset_k(vaddress));
}
__flush_tlb_all();
+
+ return save_pgd;
}
-void __init efi_call_phys_epilog(void)
+void __init efi_call_phys_epilog(pgd_t *save_pgd)
{
/*
* After the lock is released, the original page table is restored.
*/
- int pgd;
- int n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);
+ int pgd_idx;
+ int nr_pgds;
- if (!efi_enabled(EFI_OLD_MEMMAP))
+ if (!save_pgd)
return;
- for (pgd = 0; pgd < n_pgds; pgd++)
- set_pgd(pgd_offset_k(pgd * PGDIR_SIZE), save_pgd[pgd]);
+ nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);
+
+ for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++)
+ set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);
+
kfree(save_pgd);
+
__flush_tlb_all();
early_code_mapping_set_exec(0);
}
--
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