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| author | Michael Ellerman <mpe@ellerman.id.au> | 2017-06-06 08:48:57 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-06-15 09:34:39 +0300 |
| commit | 9abcc981de9775659a0f6e4a52a3448ea72e59da (patch) | |
| tree | 203f821fb6d73a41dfd97c8fca401a5615a4597f /arch | |
| parent | 0edc2ca9ccc9df99f7a94b6407ae2a0ff27d86b2 (diff) | |
| download | linux-9abcc981de9775659a0f6e4a52a3448ea72e59da.tar.xz | |
powerpc/mm/radix: Only add X for pages overlapping kernel text
Currently we map the whole linear mapping with PAGE_KERNEL_X. Instead we
should check if the page overlaps the kernel text and only then add
PAGE_KERNEL_X.
Note that we still use 1G pages if they're available, so this will
typically still result in a 1G executable page at KERNELBASE. So this fix is
primarily useful for catching stray branches to high linear mapping addresses.
Without this patch, we can execute at 1G in xmon using:
0:mon> m c000000040000000
c000000040000000 00 l
c000000040000000 00000000 01006038
c000000040000004 00000000 2000804e
c000000040000008 00000000 x
0:mon> di c000000040000000
c000000040000000 38600001 li r3,1
c000000040000004 4e800020 blr
0:mon> p c000000040000000
return value is 0x1
After we get a 400 as expected:
0:mon> p c000000040000000
*** 400 exception occurred
Fixes: 2bfd65e45e87 ("powerpc/mm/radix: Add radix callbacks for early init routines")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/mm/pgtable-radix.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c index c28165d8970b..6c062f92b9e4 100644 --- a/arch/powerpc/mm/pgtable-radix.c +++ b/arch/powerpc/mm/pgtable-radix.c @@ -19,6 +19,7 @@ #include <asm/mmu.h> #include <asm/firmware.h> #include <asm/powernv.h> +#include <asm/sections.h> #include <trace/events/thp.h> @@ -121,7 +122,8 @@ static inline void __meminit print_mapping(unsigned long start, static int __meminit create_physical_mapping(unsigned long start, unsigned long end) { - unsigned long addr, mapping_size = 0; + unsigned long vaddr, addr, mapping_size = 0; + pgprot_t prot; start = _ALIGN_UP(start, PAGE_SIZE); for (addr = start; addr < end; addr += mapping_size) { @@ -145,8 +147,14 @@ static int __meminit create_physical_mapping(unsigned long start, start = addr; } - rc = radix__map_kernel_page((unsigned long)__va(addr), addr, - PAGE_KERNEL_X, mapping_size); + vaddr = (unsigned long)__va(addr); + + if (overlaps_kernel_text(vaddr, vaddr + mapping_size)) + prot = PAGE_KERNEL_X; + else + prot = PAGE_KERNEL; + + rc = radix__map_kernel_page(vaddr, addr, prot, mapping_size); if (rc) return rc; } |