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authorLinus Torvalds <torvalds@linux-foundation.org>2012-10-01 13:59:17 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-01 13:59:17 -0700
commit15385dfe7e0fa6866b204dd0d14aec2cc48fc0a7 (patch)
tree3ddcb000ec3b82f672fa892e8e44b1be4a5ebb33 /arch/x86/mm
parenta57d985e378ca69f430b85852e4187db3698a89e (diff)
parentb2cc2a074de75671bbed5e2dda67a9252ef353ea (diff)
downloadblackbird-op-linux-15385dfe7e0fa6866b204dd0d14aec2cc48fc0a7.tar.gz
blackbird-op-linux-15385dfe7e0fa6866b204dd0d14aec2cc48fc0a7.zip
Merge branch 'x86-smap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86/smap support from Ingo Molnar: "This adds support for the SMAP (Supervisor Mode Access Prevention) CPU feature on Intel CPUs: a hardware feature that prevents unintended user-space data access from kernel privileged code. It's turned on automatically when possible. This, in combination with SMEP, makes it even harder to exploit kernel bugs such as NULL pointer dereferences." Fix up trivial conflict in arch/x86/kernel/entry_64.S due to newly added includes right next to each other. * 'x86-smap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, smep, smap: Make the switching functions one-way x86, suspend: On wakeup always initialize cr4 and EFER x86-32: Start out eflags and cr4 clean x86, smap: Do not abuse the [f][x]rstor_checking() functions for user space x86-32, smap: Add STAC/CLAC instructions to 32-bit kernel entry x86, smap: Reduce the SMAP overhead for signal handling x86, smap: A page fault due to SMAP is an oops x86, smap: Turn on Supervisor Mode Access Prevention x86, smap: Add STAC and CLAC instructions to control user space access x86, uaccess: Merge prototypes for clear_user/__clear_user x86, smap: Add a header file with macros for STAC/CLAC x86, alternative: Add header guards to <asm/alternative-asm.h> x86, alternative: Use .pushsection/.popsection x86, smap: Add CR4 bit for SMAP x86-32, mm: The WP test should be done on a kernel page
Diffstat (limited to 'arch/x86/mm')
-rw-r--r--arch/x86/mm/fault.c18
-rw-r--r--arch/x86/mm/init_32.c2
2 files changed, 19 insertions, 1 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 7dde46d68a25..a530b230e7d7 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -996,6 +996,17 @@ static int fault_in_kernel_space(unsigned long address)
return address >= TASK_SIZE_MAX;
}
+static inline bool smap_violation(int error_code, struct pt_regs *regs)
+{
+ if (error_code & PF_USER)
+ return false;
+
+ if (!user_mode_vm(regs) && (regs->flags & X86_EFLAGS_AC))
+ return false;
+
+ return true;
+}
+
/*
* This routine handles page faults. It determines the address,
* and the problem, and then passes it off to one of the appropriate
@@ -1089,6 +1100,13 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
if (unlikely(error_code & PF_RSVD))
pgtable_bad(regs, error_code, address);
+ if (static_cpu_has(X86_FEATURE_SMAP)) {
+ if (unlikely(smap_violation(error_code, regs))) {
+ bad_area_nosemaphore(regs, error_code, address);
+ return;
+ }
+ }
+
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
/*
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 4f04db150027..11a58001b4ce 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -709,7 +709,7 @@ static void __init test_wp_bit(void)
"Checking if this processor honours the WP bit even in supervisor mode...");
/* Any page-aligned address will do, the test is non-destructive */
- __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_READONLY);
+ __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_KERNEL_RO);
boot_cpu_data.wp_works_ok = do_test_wp_bit();
clear_fixmap(FIX_WP_TEST);
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