trans_rvv.c.inc: mark_vs_dirty() before loads and stores

While discussing a problem with how we're (not) setting vstart_eq_zero
Richard had the following to say w.r.t the conditional mark_vs_dirty()
calls on load/store functions [1]:

"I think it's required to have stores set dirty unconditionally, before
the operation.

Consider a store that traps on the 2nd element, leaving vstart = 2, and
exiting to the main loop via exception. The exception enters the kernel
page fault handler. The kernel may need to fault in the page for the
process, and in the meantime task switch.

If vs dirty is not already set, the kernel won't know to save vector
state on task switch."

Do a mark_vs_dirty() before both loads and stores.

[1] https://lore.kernel.org/qemu-riscv/72c7503b-0f43-44b8-aa82-fbafed2aac0c@linaro.org/

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240306171932.549549-2-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

diff --git a/target/riscv/insn_trans/trans_rvv.c.inc b/target/riscv/insn_trans/trans_rvv.c.inc
index 742008f58b874c8f952cca117fa1cd12f10764c4..b838b8ea5b8fd2d23dfa440338cc13785fe717f8 100644 (file)
--- a/target/riscv/insn_trans/trans_rvv.c.inc
+++ b/target/riscv/insn_trans/trans_rvv.c.inc
@@ -652,16 +652,14 @@ static bool ldst_us_trans(uint32_t vd, uint32_t rs1, uint32_t data,
         tcg_gen_mb(TCG_MO_ALL | TCG_BAR_STRL);
     }
 
+    mark_vs_dirty(s);
+
     fn(dest, mask, base, tcg_env, desc);
 
     if (!is_store && s->ztso) {
         tcg_gen_mb(TCG_MO_ALL | TCG_BAR_LDAQ);
     }
 
-    if (!is_store) {
-        mark_vs_dirty(s);
-    }
-
     gen_set_label(over);
     return true;
 }
@@ -817,11 +815,9 @@ static bool ldst_stride_trans(uint32_t vd, uint32_t rs1, uint32_t rs2,
     tcg_gen_addi_ptr(dest, tcg_env, vreg_ofs(s, vd));
     tcg_gen_addi_ptr(mask, tcg_env, vreg_ofs(s, 0));
 
-    fn(dest, mask, base, stride, tcg_env, desc);
+    mark_vs_dirty(s);
 
-    if (!is_store) {
-        mark_vs_dirty(s);
-    }
+    fn(dest, mask, base, stride, tcg_env, desc);
 
     gen_set_label(over);
     return true;
@@ -924,11 +920,9 @@ static bool ldst_index_trans(uint32_t vd, uint32_t rs1, uint32_t vs2,
     tcg_gen_addi_ptr(index, tcg_env, vreg_ofs(s, vs2));
     tcg_gen_addi_ptr(mask, tcg_env, vreg_ofs(s, 0));
 
-    fn(dest, mask, base, index, tcg_env, desc);
+    mark_vs_dirty(s);
 
-    if (!is_store) {
-        mark_vs_dirty(s);
-    }
+    fn(dest, mask, base, index, tcg_env, desc);
 
     gen_set_label(over);
     return true;
@@ -1122,11 +1116,10 @@ static bool ldst_whole_trans(uint32_t vd, uint32_t rs1, uint32_t nf,
     base = get_gpr(s, rs1, EXT_NONE);
     tcg_gen_addi_ptr(dest, tcg_env, vreg_ofs(s, vd));
 
+    mark_vs_dirty(s);
+
     fn(dest, base, tcg_env, desc);
 
-    if (!is_store) {
-        mark_vs_dirty(s);
-    }
     gen_set_label(over);
 
     return true;