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Message-ID: <20231018162827.GDZTAHq/Cid4gJJEiw@fat_crate.local>
Date: Wed, 18 Oct 2023 18:28:27 +0200
From: Borislav Petkov <bp@...en8.de>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>, x86@...nel.org
Subject: Re: [patch V5 03/39] x86/boot/32: De-uglify the 2/3 level paging
difference in mk_early_pgtbl_32()
On Wed, Oct 18, 2023 at 03:20:10PM +0200, Thomas Gleixner wrote:
> Up to the point where the compiler complains about a missing prototype
> for a global visible function, which will bring it back faster than you
> think. :)
---
From: Thomas Gleixner <tglx@...utronix.de>
Date: Tue, 17 Oct 2023 23:23:26 +0200
Subject: [PATCH] x86/boot/32: De-uglify the 2/3 level paging difference in
mk_early_pgtbl_32()
Move the ifdeffery out of the function and use proper typedefs to make it
work for both 2 and 3 level paging.
No functional change.
[ bp: Move mk_early_pgtbl_32() declaration into a header. ]
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20231017211722.111059491@linutronix.de
---
arch/x86/include/asm/setup.h | 1 +
arch/x86/kernel/head32.c | 38 +++++++++++++++++++-----------------
2 files changed, 21 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f3495623ac99..bf483fcb4e57 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -126,6 +126,7 @@ void clear_bss(void);
#ifdef __i386__
asmlinkage void __init __noreturn i386_start_kernel(void);
+void __init mk_early_pgtbl_32(void);
#else
asmlinkage void __init __noreturn x86_64_start_kernel(char *real_mode);
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 8fe0dd38fff0..2b6599807026 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -69,41 +69,43 @@ asmlinkage __visible void __init __noreturn i386_start_kernel(void)
* to the first kernel PMD. Note the upper half of each PMD or PTE are
* always zero at this stage.
*/
-void __init mk_early_pgtbl_32(void);
+#ifdef CONFIG_X86_PAE
+typedef pmd_t pl2_t;
+#define pl2_base initial_pg_pmd
+#define SET_PL2(val) { .pmd = (val), }
+#else
+typedef pgd_t pl2_t;
+#define pl2_base initial_page_table
+#define SET_PL2(val) { .pgd = (val), }
+#endif
void __init __no_stack_protector mk_early_pgtbl_32(void)
{
- pte_t pte, *ptep;
- int i;
- unsigned long *ptr;
/* Enough space to fit pagetables for the low memory linear map */
const unsigned long limit = __pa_nodebug(_end) +
(PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT);
-#ifdef CONFIG_X86_PAE
- pmd_t pl2, *pl2p = (pmd_t *)__pa_nodebug(initial_pg_pmd);
-#define SET_PL2(pl2, val) { (pl2).pmd = (val); }
-#else
- pgd_t pl2, *pl2p = (pgd_t *)__pa_nodebug(initial_page_table);
-#define SET_PL2(pl2, val) { (pl2).pgd = (val); }
-#endif
+ pte_t pte, *ptep = (pte_t *)__pa_nodebug(__brk_base);
+ pl2_t *pl2p = (pl2_t *)__pa_nodebug(pl2_base);
+ unsigned long *ptr;
+ int i;
- ptep = (pte_t *)__pa_nodebug(__brk_base);
pte.pte = PTE_IDENT_ATTR;
while ((pte.pte & PTE_PFN_MASK) < limit) {
+ pl2_t pl2 = SET_PL2((unsigned long)ptep | PDE_IDENT_ATTR);
- SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR);
*pl2p = pl2;
-#ifndef CONFIG_X86_PAE
- /* Kernel PDE entry */
- *(pl2p + ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
-#endif
+
+ if (!IS_ENABLED(CONFIG_X86_PAE)) {
+ /* Kernel PDE entry */
+ *(pl2p + ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2;
+ }
+
for (i = 0; i < PTRS_PER_PTE; i++) {
*ptep = pte;
pte.pte += PAGE_SIZE;
ptep++;
}
-
pl2p++;
}
--
2.42.0.rc0.25.ga82fb66fed25
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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