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authorMike Rapoport <rppt@linux.ibm.com>2020-06-08 21:33:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-09 09:39:13 -0700
commit88107d330de4f175705a3ea03147feb0d7e68499 (patch)
tree3a73f1bd2b03ad0b41e9cb262e09ab2d4fd4a3cb /arch/x86/mm
parent1bcdc68d6a69440ff82c3e492cd383059852bdd7 (diff)
x86/mm: simplify init_trampoline() and surrounding logic
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>
Diffstat (limited to 'arch/x86/mm')
-rw-r--r--arch/x86/mm/init.c22
-rw-r--r--arch/x86/mm/kaslr.c33
2 files changed, 23 insertions, 32 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 112d3b98a3b6..001dd7dc829f 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -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;
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index faf02e1e1517..fb620fd9dae9 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -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();
-}