diff options
| author | Jan Beulich <jbeulich@suse.com> | 2019-11-18 16:21:12 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-11-19 21:58:28 +0100 |
| commit | 81ff2c37f9e5d77593928df0536d86443195fd64 (patch) | |
| tree | b3c5ddb89e3740c3cbd640f3f98517f5d4becb33 /arch/x86/include/asm/segment.h | |
| parent | af42d3466bdc8f39806b26f593604fdc54140bcb (diff) | |
x86/stackframe/32: Repair 32-bit Xen PV
Once again RPL checks have been introduced which don't account for a 32-bit
kernel living in ring 1 when running in a PV Xen domain. The case in
FIXUP_FRAME has been preventing boot.
Adjust BUG_IF_WRONG_CR3 as well to guard against future uses of the macro
on a code path reachable when running in PV mode under Xen; I have to admit
that I stopped at a certain point trying to figure out whether there are
present ones.
Fixes: 3c88c692c287 ("x86/stackframe/32: Provide consistent pt_regs")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Stable Team <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/0fad341f-b7f5-f859-d55d-f0084ee7087e@suse.com
Diffstat (limited to 'arch/x86/include/asm/segment.h')
| -rw-r--r-- | arch/x86/include/asm/segment.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index ac3892920419..6669164abadc 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -31,6 +31,18 @@ */ #define SEGMENT_RPL_MASK 0x3 +/* + * When running on Xen PV, the actual privilege level of the kernel is 1, + * not 0. Testing the Requested Privilege Level in a segment selector to + * determine whether the context is user mode or kernel mode with + * SEGMENT_RPL_MASK is wrong because the PV kernel's privilege level + * matches the 0x3 mask. + * + * Testing with USER_SEGMENT_RPL_MASK is valid for both native and Xen PV + * kernels because privilege level 2 is never used. + */ +#define USER_SEGMENT_RPL_MASK 0x2 + /* User mode is privilege level 3: */ #define USER_RPL 0x3 |