[PATCH v7 07/14] x86/cet/ibt: Add arch_prctl functions for IBT

[Yu-cheng Yu]

Update ARCH_X86_CET_STATUS and ARCH_X86_CET_DISABLE to include
Indirect Branch Tracking features.

Introduce:

arch_prctl(ARCH_X86_CET_SET_LEGACY_BITMAP, unsigned long *addr)
    Enable the Indirect Branch Tracking legacy code bitmap.

    The parameter 'addr' is a pointer to a user buffer that has:

    *addr = IBT bitmap base address
    *(addr + 1) = IBT bitmap size

Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng...@intel.com>
---
 arch/x86/include/uapi/asm/prctl.h |  2 ++
 arch/x86/kernel/cet_prctl.c       | 21 +++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/arch/x86/include/uapi/asm/prctl.h 
b/arch/x86/include/uapi/asm/prctl.h
index d962f0ec9ccf..5eb9aeb5c662 100644
--- a/arch/x86/include/uapi/asm/prctl.h
+++ b/arch/x86/include/uapi/asm/prctl.h
@@ -18,5 +18,7 @@
 #define ARCH_X86_CET_DISABLE           0x3002
 #define ARCH_X86_CET_LOCK              0x3003
 #define ARCH_X86_CET_ALLOC_SHSTK       0x3004
+#define ARCH_X86_CET_GET_LEGACY_BITMAP 0x3005 /* deprecated */
+#define ARCH_X86_CET_SET_LEGACY_BITMAP 0x3006
 
 #endif /* _ASM_X86_PRCTL_H */
diff --git a/arch/x86/kernel/cet_prctl.c b/arch/x86/kernel/cet_prctl.c
index 9c9d4262b07e..b7f37bbc0dd3 100644
--- a/arch/x86/kernel/cet_prctl.c
+++ b/arch/x86/kernel/cet_prctl.c
@@ -20,6 +20,8 @@ static int handle_get_status(unsigned long arg2)
 
        if (current->thread.cet.shstk_enabled)
                features |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
+       if (current->thread.cet.ibt_enabled)
+               features |= GNU_PROPERTY_X86_FEATURE_1_IBT;
 
        shstk_base = current->thread.cet.shstk_base;
        shstk_size = current->thread.cet.shstk_size;
@@ -55,6 +57,17 @@ static int handle_alloc_shstk(unsigned long arg2)
        return 0;
 }
 
+static int handle_bitmap(unsigned long arg2)
+{
+       unsigned long addr, size;
+
+       if (get_user(addr, (unsigned long __user *)arg2) ||
+           get_user(size, (unsigned long __user *)arg2 + 1))
+               return -EFAULT;
+
+       return cet_setup_ibt_bitmap(addr, size);
+}
+
 int prctl_cet(int option, unsigned long arg2)
 {
        if (!cpu_x86_cet_enabled())
@@ -69,6 +82,8 @@ int prctl_cet(int option, unsigned long arg2)
                        return -EPERM;
                if (arg2 & GNU_PROPERTY_X86_FEATURE_1_SHSTK)
                        cet_disable_free_shstk(current);
+               if (arg2 & GNU_PROPERTY_X86_FEATURE_1_IBT)
+                       cet_disable_ibt();
 
                return 0;
 
@@ -79,6 +94,12 @@ int prctl_cet(int option, unsigned long arg2)
        case ARCH_X86_CET_ALLOC_SHSTK:
                return handle_alloc_shstk(arg2);
 
+       /*
+        * Allocate legacy bitmap and return address & size to user.
+        */
+       case ARCH_X86_CET_SET_LEGACY_BITMAP:
+               return handle_bitmap(arg2);
+
        default:
                return -EINVAL;
        }
-- 
2.17.1