diff mbox series

[v4,37/57] tcg/loongarch64: Support softmmu unaligned accesses

Message ID 20230503070656.1746170-38-richard.henderson@linaro.org
State New
Headers show
Series tcg: Improve atomicity support | expand

Commit Message

Richard Henderson May 3, 2023, 7:06 a.m. UTC 
Test the final byte of an unaligned access.
Use BSTRINS.D to clear the range of bits, rather than AND.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/loongarch64/tcg-target.c.inc | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

Comments

Peter Maydell May 5, 2023, 12:35 p.m. UTC | #1 
On Wed, 3 May 2023 at 08:25, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Test the final byte of an unaligned access.
> Use BSTRINS.D to clear the range of bits, rather than AND.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

(at least, it's the same general shape as other architectures;
I have no loongarch-specific knowledge)

thanks
-- PMM
diff mbox series

Patch

diff --git a/tcg/loongarch64/tcg-target.c.inc b/tcg/loongarch64/tcg-target.c.inc
index ccc13ffdb4..20cb21b264 100644
--- a/tcg/loongarch64/tcg-target.c.inc
+++ b/tcg/loongarch64/tcg-target.c.inc
@@ -848,7 +848,6 @@  static TCGLabelQemuLdst *prepare_host_addr(TCGContext *s, HostAddress *h,
     int fast_ofs = TLB_MASK_TABLE_OFS(mem_index);
     int mask_ofs = fast_ofs + offsetof(CPUTLBDescFast, mask);
     int table_ofs = fast_ofs + offsetof(CPUTLBDescFast, table);
-    tcg_target_long compare_mask;
 
     ldst = new_ldst_label(s);
     ldst->is_ld = is_ld;
@@ -872,14 +871,20 @@  static TCGLabelQemuLdst *prepare_host_addr(TCGContext *s, HostAddress *h,
     tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_TMP2, TCG_REG_TMP2,
                offsetof(CPUTLBEntry, addend));
 
-    /* We don't support unaligned accesses.  */
+    /*
+     * For aligned accesses, we check the first byte and include the alignment
+     * bits within the address.  For unaligned access, we check that we don't
+     * cross pages using the address of the last byte of the access.
+     */
     if (a_bits < s_bits) {
-        a_bits = s_bits;
+        unsigned a_mask = (1u << a_bits) - 1;
+        unsigned s_mask = (1u << s_bits) - 1;
+        tcg_out_addi(s, TCG_TYPE_TL, TCG_REG_TMP1, addr_reg, s_mask - a_mask);
+    } else {
+        tcg_out_mov(s, TCG_TYPE_TL, TCG_REG_TMP1, addr_reg);
     }
-    /* Clear the non-page, non-alignment bits from the address.  */
-    compare_mask = (tcg_target_long)TARGET_PAGE_MASK | ((1 << a_bits) - 1);
-    tcg_out_movi(s, TCG_TYPE_TL, TCG_REG_TMP1, compare_mask);
-    tcg_out_opc_and(s, TCG_REG_TMP1, TCG_REG_TMP1, addr_reg);
+    tcg_out_opc_bstrins_d(s, TCG_REG_TMP1, TCG_REG_ZERO,
+                          a_bits, TARGET_PAGE_BITS - 1);
 
     /* Compare masked address with the TLB entry.  */
     ldst->label_ptr[0] = s->code_ptr;