From c0f1d478121131c2a97cab24148bf7ebb7ed3434 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Fri, 25 Aug 2023 14:29:48 +0200 Subject: s390/mm: simplify kernel mapping setup The kernel mapping is setup in two stages: in the decompressor map all pages with RWX permissions, and within the kernel change all mappings to their final permissions, where most of the mappings are changed from RWX to RWNX. Change this and map all pages RWNX from the beginning, however without enabling noexec via control register modification. This means that effectively all pages are used with RWX permissions like before. When the final permissions have been applied to the kernel mapping enable noexec via control register modification. This allows to remove quite a bit of non-obvious code. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens --- arch/s390/boot/startup.c | 4 +--- arch/s390/boot/vmem.c | 12 +++++++++--- 2 files changed, 10 insertions(+), 6 deletions(-) (limited to 'arch/s390/boot') diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index caf562be3531..d3e48bd9c394 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -53,10 +53,8 @@ static void detect_facilities(void) } if (test_facility(78)) machine.has_edat2 = 1; - if (test_facility(130)) { + if (test_facility(130)) machine.has_nx = 1; - __ctl_set_bit(0, 20); - } } static void setup_lpp(void) diff --git a/arch/s390/boot/vmem.c b/arch/s390/boot/vmem.c index c67f59db7a51..01257ce3b89c 100644 --- a/arch/s390/boot/vmem.c +++ b/arch/s390/boot/vmem.c @@ -287,7 +287,9 @@ static void pgtable_pte_populate(pmd_t *pmd, unsigned long addr, unsigned long e if (kasan_pte_populate_zero_shadow(pte, mode)) continue; entry = __pte(_pa(addr, PAGE_SIZE, mode)); - entry = set_pte_bit(entry, PAGE_KERNEL_EXEC); + entry = set_pte_bit(entry, PAGE_KERNEL); + if (!machine.has_nx) + entry = clear_pte_bit(entry, __pgprot(_PAGE_NOEXEC)); set_pte(pte, entry); pages++; } @@ -311,7 +313,9 @@ static void pgtable_pmd_populate(pud_t *pud, unsigned long addr, unsigned long e continue; if (can_large_pmd(pmd, addr, next)) { entry = __pmd(_pa(addr, _SEGMENT_SIZE, mode)); - entry = set_pmd_bit(entry, SEGMENT_KERNEL_EXEC); + entry = set_pmd_bit(entry, SEGMENT_KERNEL); + if (!machine.has_nx) + entry = clear_pmd_bit(entry, __pgprot(_SEGMENT_ENTRY_NOEXEC)); set_pmd(pmd, entry); pages++; continue; @@ -342,7 +346,9 @@ static void pgtable_pud_populate(p4d_t *p4d, unsigned long addr, unsigned long e continue; if (can_large_pud(pud, addr, next)) { entry = __pud(_pa(addr, _REGION3_SIZE, mode)); - entry = set_pud_bit(entry, REGION3_KERNEL_EXEC); + entry = set_pud_bit(entry, REGION3_KERNEL); + if (!machine.has_nx) + entry = clear_pud_bit(entry, __pgprot(_REGION_ENTRY_NOEXEC)); set_pud(pud, entry); pages++; continue; -- cgit v1.2.3