AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2024-11-24 09:51:00 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity

x86/mm: simplify init_trampoline() and surrounding logic

Browse Source 
There are three cases for the trampoline initialization:
* 32-bit does nothing
* 64-bit with kaslr disabled simply copies a PGD entry from the direct map
  to the trampoline PGD
* 64-bit with kaslr enabled maps the real mode trampoline at PUD level

These cases are currently differentiated by a bunch of ifdefs inside
asm/include/pgtable.h and the case of 64-bits with kaslr on uses
pgd_index() helper.

Replacing the ifdefs with a static function in arch/x86/mm/init.c gives
clearer code and allows moving pgd_index() to the generic implementation
in include/linux/pgtable.h

[rppt@linux.ibm.com: take CONFIG_RANDOMIZE_MEMORY into account in kaslr_enabled()]
  Link: http://lkml.kernel.org/r/20200525104045.GB13212@linux.ibm.com

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200514170327.31389-8-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Rapoport 2020-06-08 21:33:01 -07:00 committed by Linus Torvalds
parent 1bcdc68d6a
commit 88107d330d
5 changed files with 37 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/kaslr.h
View File

@ -6,8 +6,10 @@ unsigned long kaslr_get_random_long(const char *purpose);
#ifdef CONFIG_RANDOMIZE_MEMORY
void kernel_randomize_memory(void);
void init_trampoline_kaslr(void);
#else
static inline void kernel_randomize_memory(void) { }
static inline void init_trampoline_kaslr(void) {}
#endif /* CONFIG_RANDOMIZE_MEMORY */
#endif

15
arch/x86/include/asm/pgtable.h
View File

@ -1071,27 +1071,14 @@ void init_mem_mapping(void);
void early_alloc_pgt_buf(void);
extern void memblock_find_dma_reserve(void);
#ifdef CONFIG_X86_64
/* Realmode trampoline initialization. */
extern pgd_t trampoline_pgd_entry;
static inline void __meminit init_trampoline_default(void)
{
/* Default trampoline pgd value */
trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)];
}
void __init poking_init(void);
unsigned long init_memory_mapping(unsigned long start,
unsigned long end, pgprot_t prot);
# ifdef CONFIG_RANDOMIZE_MEMORY
void __meminit init_trampoline(void);
# else
# define init_trampoline init_trampoline_default
# endif
#else
static inline void init_trampoline(void) { }
#endif
/* local pte updates need not use xchg for locking */

12
arch/x86/include/asm/setup.h
View File

@ -75,7 +75,17 @@ extern char _text[];
static inline bool kaslr_enabled(void)
{
return !!(boot_params.hdr.loadflags & KASLR_FLAG);
return IS_ENABLED(CONFIG_RANDOMIZE_MEMORY) &&
!!(boot_params.hdr.loadflags & KASLR_FLAG);
}
/*
* Apply no randomization if KASLR was disabled at boot or if KASAN
* is enabled. KASAN shadow mappings rely on regions being PGD aligned.
*/
static inline bool kaslr_memory_enabled(void)
{
return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN);
}
static inline unsigned long kaslr_offset(void)

22
arch/x86/mm/init.c
View File

@ -680,6 +680,28 @@ static void __init memory_map_bottom_up(unsigned long map_start,
}
}
/*
* The real mode trampoline, which is required for bootstrapping CPUs
* occupies only a small area under the low 1MB. See reserve_real_mode()
* for details.
*
* If KASLR is disabled the first PGD entry of the direct mapping is copied
* to map the real mode trampoline.
*
* If KASLR is enabled, copy only the PUD which covers the low 1MB
* area. This limits the randomization granularity to 1GB for both 4-level
* and 5-level paging.
*/
static void __init init_trampoline(void)
{
#ifdef CONFIG_X86_64
if (!kaslr_memory_enabled())
trampoline_pgd_entry = init_top_pgt[pgd_index(__PAGE_OFFSET)];
else
init_trampoline_kaslr();
#endif
}
void __init init_mem_mapping(void)
{
unsigned long end;

33
arch/x86/mm/kaslr.c
View File

@ -61,15 +61,6 @@ static inline unsigned long get_padding(struct kaslr_memory_region *region)
return (region->size_tb << TB_SHIFT);
}
/*
* Apply no randomization if KASLR was disabled at boot or if KASAN
* is enabled. KASAN shadow mappings rely on regions being PGD aligned.
*/
static inline bool kaslr_memory_enabled(void)
{
return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN);
}
/* Initialize base and padding for each memory region randomized with KASLR */
void __init kernel_randomize_memory(void)
{
@ -148,7 +139,7 @@ void __init kernel_randomize_memory(void)
}
}
static void __meminit init_trampoline_pud(void)
void __meminit init_trampoline_kaslr(void)
{
pud_t *pud_page_tramp, *pud, *pud_tramp;
p4d_t *p4d_page_tramp, *p4d, *p4d_tramp;
@ -189,25 +180,3 @@ static void __meminit init_trampoline_pud(void)
__pgd(_KERNPG_TABLE | __pa(pud_page_tramp)));
}
}
/*
* The real mode trampoline, which is required for bootstrapping CPUs
* occupies only a small area under the low 1MB. See reserve_real_mode()
* for details.
*
* If KASLR is disabled the first PGD entry of the direct mapping is copied
* to map the real mode trampoline.
*
* If KASLR is enabled, copy only the PUD which covers the low 1MB
* area. This limits the randomization granularity to 1GB for both 4-level
* and 5-level paging.
*/
void __meminit init_trampoline(void)
{
if (!kaslr_memory_enabled()) {
init_trampoline_default();
return;
}
init_trampoline_pud();
}