Commit 121d5d0a authored Feb 20, 2009 by Ingo Molnar

x86, mm: fault.c, enable PF_RSVD checks on 32-bit too



Impact: improve page fault handling robustness

The 'PF_RSVD' flag (bit 3) of the page-fault error_code is a
relatively recent addition to x86 CPUs, so the 32-bit do_fault()
implementation never had it. This flag gets set when the CPU
detects nonzero values in any reserved bits of the page directory
entries.

Extend the existing 64-bit check for PF_RSVD in do_page_fault()
to 32-bit too. If we detect such a fault then we print a more
informative oops and the pagetables.

This unifies the code some more, removes an ugly #ifdef and improves
the 32-bit page fault code robustness a bit. It slightly increases
the 32-bit kernel text size.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 8c938f9f

arch/x86/mm/fault.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -477,7 +477,6 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
		dump_pagetable(address);
		}

		#ifdef CONFIG_X86_64
		static noinline void
		pgtable_bad(struct pt_regs *regs, unsigned long error_code,
		unsigned long address)
		@@ -503,7 +502,6 @@ pgtable_bad(struct pt_regs *regs, unsigned long error_code,

		oops_end(flags, regs, sig);
		}
		#endif

		static noinline void
		no_context(struct pt_regs *regs, unsigned long error_code,
		@@ -1015,10 +1013,8 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
		local_irq_enable();
		}

		#ifdef CONFIG_X86_64
		if (unlikely(error_code & PF_RSVD))
		pgtable_bad(regs, error_code, address);
		#endif

		/*
		* If we're in an interrupt, have no user context or are running

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