arm64: fix el2_setup check of CurrentEL

The CurrentEL system register reports the Current Exception Level
of the CPU. It doesn't say anything about the stack handling, and
yet we compare it to PSR_MODE_EL2t and PSR_MODE_EL2h.

It works by chance because PSR_MODE_EL2t happens to match the right
bits, but that's otherwise a very bad idea. Just check for the EL
value instead.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[catalin.marinas@arm.com: fixed arch/arm64/kernel/efi-entry.S]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

3 files changed, 6 insertions, 4 deletions

diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index a429b5940be2..501000fadb6f 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -21,6 +21,10 @@
 
 #include <uapi/asm/ptrace.h>
 
+/* Current Exception Level values, as contained in CurrentEL */
+#define CurrentEL_EL1           (1 << 2)
+#define CurrentEL_EL2           (2 << 2)
+
 /* AArch32-specific ptrace requests */
 #define COMPAT_PTRACE_GETREGS           12
 #define COMPAT_PTRACE_SETREGS           13
diff --git a/arch/arm64/kernel/efi-entry.S b/arch/arm64/kernel/efi-entry.S
index 66716c9b9e5f..619b1dd7bcde 100644
--- a/arch/arm64/kernel/efi-entry.S
+++ b/arch/arm64/kernel/efi-entry.S
@@ -78,8 +78,7 @@ ENTRY(efi_stub_entry)
 
         /* Turn off Dcache and MMU */
         mrs     x0, CurrentEL
-        cmp     x0, #PSR_MODE_EL2t
-        ccmp    x0, #PSR_MODE_EL2h, #0x4, ne
+        cmp     x0, #CurrentEL_EL2
         b.ne    1f
         mrs     x0, sctlr_el2
         bic     x0, x0, #1 << 0 // clear SCTLR.M
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index a96d3a6a63f6..a2c1195abb7f 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -270,8 +270,7 @@ ENDPROC(stext)
  */
 ENTRY(el2_setup)
         mrs     x0, CurrentEL
-        cmp     x0, #PSR_MODE_EL2t
-        ccmp    x0, #PSR_MODE_EL2h, #0x4, ne
+        cmp     x0, #CurrentEL_EL2
         b.ne    1f
         mrs     x0, sctlr_el2
 CPU_BE( orr     x0, x0, #(1 << 25)      )       // Set the EE bit for EL2