Re: [PATCH v2] target/loongarch: fix bad shift in check_ps()

[bibo mao]

On 2025/3/21 上午9:13, Song Gao wrote:

  In expression 1ULL << tlb_ps, left shifting by more than 63 bits has 
undefined behavior.
The shift amount, tlb_ps, is as much as 64. check "tlb_ps >=64" to fix.

Resolves: Coverity CID 1593475

Fixes: d882c284a3 ("target/loongarch: check tlb_ps")
Suggested-by: Peter Maydell <peter.mayd...@linaro.org>
Signed-off-by: Song Gao <gaos...@loongson.cn>
---
v2:  define parameter tlb_ps as uint type

  target/loongarch/internals.h      |  2 +-
  target/loongarch/tcg/csr_helper.c |  2 +-
  target/loongarch/tcg/tlb_helper.c | 10 +++++-----
  3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/target/loongarch/internals.h b/target/loongarch/internals.h
index 1cd959a766..9fdc3059d8 100644
--- a/target/loongarch/internals.h
+++ b/target/loongarch/internals.h
@@ -43,7 +43,7 @@ enum {
      TLBRET_PE = 7,
  };

-bool check_ps(CPULoongArchState *ent, int ps);

+bool check_ps(CPULoongArchState *ent, uint8_t ps);

extern const VMStateDescription vmstate_loongarch_cpu; diff --git a/target/loongarch/tcg/csr_helper.c b/target/loongarch/tcg/csr_helper.c

index 379c71e741..6a7a65c860 100644
--- a/target/loongarch/tcg/csr_helper.c
+++ b/target/loongarch/tcg/csr_helper.c
@@ -115,7 +115,7 @@ target_ulong helper_csrwr_ticlr(CPULoongArchState *env, 
target_ulong val)

target_ulong helper_csrwr_pwcl(CPULoongArchState *env, target_ulong val)

  {
-    int shift, ptbase;
+    uint8_t shift, ptbase;
      int64_t old_v = env->CSR_PWCL;

/*

diff --git a/target/loongarch/tcg/tlb_helper.c 
b/target/loongarch/tcg/tlb_helper.c
index 646dbf59de..bd8081e886 100644
--- a/target/loongarch/tcg/tlb_helper.c
+++ b/target/loongarch/tcg/tlb_helper.c
@@ -19,12 +19,12 @@
  #include "exec/log.h"
  #include "cpu-csr.h"

-bool check_ps(CPULoongArchState *env, int tlb_ps)

+bool check_ps(CPULoongArchState *env, uint8_t tlb_ps)
  {
-     if (tlb_ps > 64) {
-         return false;
-     }
-     return BIT_ULL(tlb_ps) & (env->CSR_PRCFG2);
+    if (tlb_ps >= 64) {
+        return false;
+    }
+    return BIT_ULL(tlb_ps) & (env->CSR_PRCFG2);
  }

void get_dir_base_width(CPULoongArchState *env, uint64_t *dir_base,

Reviewed-by: Bibo Mao <maob...@loongson.cn>