target/arm: Create pauth_ptr_mask

Keep the logic for pauth within pauth_helper.c, and expose
a helper function for use with the gdbstub pac extension.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230227213329.793795-11-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 32 insertions, 4 deletions

diff --git a/target/arm/internals.h b/target/arm/internals.h
index 15988768be..c891c7a383 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -1368,6 +1368,16 @@ int exception_target_el(CPUARMState *env);
 bool arm_singlestep_active(CPUARMState *env);
 bool arm_generate_debug_exceptions(CPUARMState *env);
 
+/**
+ * pauth_ptr_mask:
+ * @env: cpu context
+ * @ptr: selects between TTBR0 and TTBR1
+ * @data: selects between TBI and TBID
+ *
+ * Return a mask of the bits of @ptr that contain the authentication code.
+ */
+uint64_t pauth_ptr_mask(CPUARMState *env, uint64_t ptr, bool data);
+
 /* Add the cpreg definitions for debug related system registers */
 void define_debug_regs(ARMCPU *cpu);
 
diff --git a/target/arm/tcg/pauth_helper.c b/target/arm/tcg/pauth_helper.c
index d0483bf051..20f347332d 100644
--- a/target/arm/tcg/pauth_helper.c
+++ b/target/arm/tcg/pauth_helper.c
@@ -339,14 +339,32 @@ static uint64_t pauth_addpac(CPUARMState *env, uint64_t ptr, uint64_t modifier,
     return pac | ext | ptr;
 }
 
-static uint64_t pauth_original_ptr(uint64_t ptr, ARMVAParameters param)
+static uint64_t pauth_ptr_mask_internal(ARMVAParameters param)
 {
-    /* Note that bit 55 is used whether or not the regime has 2 ranges. */
-    uint64_t extfield = sextract64(ptr, 55, 1);
     int bot_pac_bit = 64 - param.tsz;
     int top_pac_bit = 64 - 8 * param.tbi;
 
-    return deposit64(ptr, bot_pac_bit, top_pac_bit - bot_pac_bit, extfield);
+    return MAKE_64BIT_MASK(bot_pac_bit, top_pac_bit - bot_pac_bit);
+}
+
+static uint64_t pauth_original_ptr(uint64_t ptr, ARMVAParameters param)
+{
+    uint64_t mask = pauth_ptr_mask_internal(param);
+
+    /* Note that bit 55 is used whether or not the regime has 2 ranges. */
+    if (extract64(ptr, 55, 1)) {
+        return ptr | mask;
+    } else {
+        return ptr & ~mask;
+    }
+}
+
+uint64_t pauth_ptr_mask(CPUARMState *env, uint64_t ptr, bool data)
+{
+    ARMMMUIdx mmu_idx = arm_stage1_mmu_idx(env);
+    ARMVAParameters param = aa64_va_parameters(env, ptr, mmu_idx, data);
+
+    return pauth_ptr_mask_internal(param);
 }
 
 static uint64_t pauth_auth(CPUARMState *env, uint64_t ptr, uint64_t modifier,