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-rw-r--r--arch/sparc/kernel/etrap_64.S27
1 files changed, 26 insertions, 1 deletions
diff --git a/arch/sparc/kernel/etrap_64.S b/arch/sparc/kernel/etrap_64.S
index 5c77a2e0e991..08cc41f64725 100644
--- a/arch/sparc/kernel/etrap_64.S
+++ b/arch/sparc/kernel/etrap_64.S
@@ -151,7 +151,32 @@ etrap_save: save %g2, -STACK_BIAS, %sp
stx %g6, [%sp + PTREGS_OFF + PT_V9_G6]
stx %g7, [%sp + PTREGS_OFF + PT_V9_G7]
or %l7, %l0, %l7
- sethi %hi(TSTATE_TSO | TSTATE_PEF), %l0
+661: sethi %hi(TSTATE_TSO | TSTATE_PEF), %l0
+ /* If userspace is using ADI, it could potentially pass
+ * a pointer with version tag embedded in it. To maintain
+ * the ADI security, we must enable PSTATE.mcde. Userspace
+ * would have already set TTE.mcd in an earlier call to
+ * kernel and set the version tag for the address being
+ * dereferenced. Setting PSTATE.mcde would ensure any
+ * access to userspace data through a system call honors
+ * ADI and does not allow a rogue app to bypass ADI by
+ * using system calls. Setting PSTATE.mcde only affects
+ * accesses to virtual addresses that have TTE.mcd set.
+ * Set PMCDPER to ensure any exceptions caused by ADI
+ * version tag mismatch are exposed before system call
+ * returns to userspace. Setting PMCDPER affects only
+ * writes to virtual addresses that have TTE.mcd set and
+ * have a version tag set as well.
+ */
+ .section .sun_m7_1insn_patch, "ax"
+ .word 661b
+ sethi %hi(TSTATE_TSO | TSTATE_PEF | TSTATE_MCDE), %l0
+ .previous
+661: nop
+ .section .sun_m7_1insn_patch, "ax"
+ .word 661b
+ .word 0xaf902001 /* wrpr %g0, 1, %pmcdper */
+ .previous
or %l7, %l0, %l7
wrpr %l2, %tnpc
wrpr %l7, (TSTATE_PRIV | TSTATE_IE), %tstate