target/i386: Fix carry flag for BLSI

target/i386: Fix tss access size in switch_tss_ra
 linux-user: Handle short reads in mmap_h_gt_g
 bsd-user: Handle short reads in mmap_h_gt_g
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Merge tag 'pull-misc-20240821' of https://gitlab.com/rth7680/qemu into staging

target/i386: Fix carry flag for BLSI
target/i386: Fix tss access size in switch_tss_ra
linux-user: Handle short reads in mmap_h_gt_g
bsd-user: Handle short reads in mmap_h_gt_g

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# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
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# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [ultimate]

* tag 'pull-misc-20240821' of https://gitlab.com/rth7680/qemu:
  target/i386: Fix tss access size in switch_tss_ra
  target/i386: Fix carry flag for BLSI
  target/i386: Split out gen_prepare_val_nz
  bsd-user: Handle short reads in mmap_h_gt_g
  linux-user: Handle short reads in mmap_h_gt_g

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

bsd-user/mmap.c

@@ -128,6 +128,40 @@ error:
     return ret;
 }
 
+/*
+ * Perform a pread on behalf of target_mmap.  We can reach EOF, we can be
+ * interrupted by signals, and in general there's no good error return path.
+ * If @zero, zero the rest of the block at EOF.
+ * Return true on success.
+ */
+static bool mmap_pread(int fd, void *p, size_t len, off_t offset, bool zero)
+{
+    while (1) {
+        ssize_t r = pread(fd, p, len, offset);
+
+        if (likely(r == len)) {
+            /* Complete */
+            return true;
+        }
+        if (r == 0) {
+            /* EOF */
+            if (zero) {
+                memset(p, 0, len);
+            }
+            return true;
+        }
+        if (r > 0) {
+            /* Short read */
+            p += r;
+            len -= r;
+            offset += r;
+        } else if (errno != EINTR) {
+            /* Error */
+            return false;
+        }
+    }
+}
+
 /*
  * map an incomplete host page
  *
@@ -190,7 +224,7 @@ static int mmap_frag(abi_ulong real_start,
             mprotect(host_start, qemu_host_page_size, prot1 | PROT_WRITE);
 
         /* read the corresponding file data */
-        if (pread(fd, g2h_untagged(start), end - start, offset) == -1) {
+        if (!mmap_pread(fd, g2h_untagged(start), end - start, offset, true)) {
             return -1;
         }
 
@@ -565,7 +599,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot,
                                   -1, 0);
             if (retaddr == -1)
                 goto fail;
-            if (pread(fd, g2h_untagged(start), len, offset) == -1) {
+            if (!mmap_pread(fd, g2h_untagged(start), len, offset, false)) {
                 goto fail;
             }
             if (!(prot & PROT_WRITE)) {

linux-user/mmap.c

@@ -283,6 +283,40 @@ static int do_munmap(void *addr, size_t len)
     return munmap(addr, len);
 }
 
+/*
+ * Perform a pread on behalf of target_mmap.  We can reach EOF, we can be
+ * interrupted by signals, and in general there's no good error return path.
+ * If @zero, zero the rest of the block at EOF.
+ * Return true on success.
+ */
+static bool mmap_pread(int fd, void *p, size_t len, off_t offset, bool zero)
+{
+    while (1) {
+        ssize_t r = pread(fd, p, len, offset);
+
+        if (likely(r == len)) {
+            /* Complete */
+            return true;
+        }
+        if (r == 0) {
+            /* EOF */
+            if (zero) {
+                memset(p, 0, len);
+            }
+            return true;
+        }
+        if (r > 0) {
+            /* Short read */
+            p += r;
+            len -= r;
+            offset += r;
+        } else if (errno != EINTR) {
+            /* Error */
+            return false;
+        }
+    }
+}
+
 /*
  * Map an incomplete host page.
  *
@@ -357,11 +391,10 @@ static bool mmap_frag(abi_ulong real_start, abi_ulong start, abi_ulong last,
     /* Read or zero the new guest pages. */
     if (flags & MAP_ANONYMOUS) {
         memset(g2h_untagged(start), 0, last - start + 1);
-    } else {
+    } else if (!mmap_pread(fd, g2h_untagged(start), last - start + 1,
-        if (pread(fd, g2h_untagged(start), last - start + 1, offset) == -1) {
+                           offset, true)) {
         return false;
     }
-    }
 
     /* Put final protection */
     if (host_prot_new != host_prot_old) {
@@ -853,8 +886,7 @@ static abi_long mmap_h_gt_g(abi_ulong start, abi_ulong len,
     }
 
     if (misaligned_offset) {
-        /* TODO: The read could be short. */
+        if (!mmap_pread(fd, p, host_len, offset + real_start - start, false)) {
-        if (pread(fd, p, host_len, offset + real_start - start) != host_len) {
             do_munmap(p, host_len);
             return -1;
         }

target/i386/cpu.h

@@ -1339,6 +1339,11 @@ typedef enum {
     CC_OP_BMILGL,
     CC_OP_BMILGQ,
 
+    CC_OP_BLSIB, /* Z,S via CC_DST, C = SRC!=0; O=0; P,A undefined */
+    CC_OP_BLSIW,
+    CC_OP_BLSIL,
+    CC_OP_BLSIQ,
+
     /*
      * Note that only CC_OP_POPCNT (i.e. the one with MO_TL size)
      * is used or implemented, because the translation needs

target/i386/tcg/cc_helper.c

@@ -186,6 +186,13 @@ target_ulong helper_cc_compute_all(target_ulong dst, target_ulong src1,
     case CC_OP_BMILGL:
         return compute_all_bmilgl(dst, src1);
 
+    case CC_OP_BLSIB:
+        return compute_all_blsib(dst, src1);
+    case CC_OP_BLSIW:
+        return compute_all_blsiw(dst, src1);
+    case CC_OP_BLSIL:
+        return compute_all_blsil(dst, src1);
+
     case CC_OP_ADCX:
         return compute_all_adcx(dst, src1, src2);
     case CC_OP_ADOX:
@@ -216,6 +223,8 @@ target_ulong helper_cc_compute_all(target_ulong dst, target_ulong src1,
         return compute_all_sarq(dst, src1);
     case CC_OP_BMILGQ:
         return compute_all_bmilgq(dst, src1);
+    case CC_OP_BLSIQ:
+        return compute_all_blsiq(dst, src1);
 #endif
     }
 }
@@ -308,6 +317,13 @@ target_ulong helper_cc_compute_c(target_ulong dst, target_ulong src1,
     case CC_OP_BMILGL:
         return compute_c_bmilgl(dst, src1);
 
+    case CC_OP_BLSIB:
+        return compute_c_blsib(dst, src1);
+    case CC_OP_BLSIW:
+        return compute_c_blsiw(dst, src1);
+    case CC_OP_BLSIL:
+        return compute_c_blsil(dst, src1);
+
 #ifdef TARGET_X86_64
     case CC_OP_ADDQ:
         return compute_c_addq(dst, src1);
@@ -321,6 +337,8 @@ target_ulong helper_cc_compute_c(target_ulong dst, target_ulong src1,
         return compute_c_shlq(dst, src1);
     case CC_OP_BMILGQ:
         return compute_c_bmilgq(dst, src1);
+    case CC_OP_BLSIQ:
+        return compute_c_blsiq(dst, src1);
 #endif
     }
 }

target/i386/tcg/cc_helper_template.h.inc

@@ -235,6 +235,24 @@ static int glue(compute_c_bmilg, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
     return src1 == 0;
 }
 
+static int glue(compute_all_blsi, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
+{
+    int cf, pf, af, zf, sf, of;
+
+    cf = (src1 != 0);
+    pf = 0; /* undefined */
+    af = 0; /* undefined */
+    zf = (dst == 0) * CC_Z;
+    sf = lshift(dst, 8 - DATA_BITS) & CC_S;
+    of = 0;
+    return cf | pf | af | zf | sf | of;
+}
+
+static int glue(compute_c_blsi, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
+{
+    return src1 != 0;
+}
+
 #undef DATA_BITS
 #undef SIGN_MASK
 #undef DATA_TYPE

target/i386/tcg/emit.c.inc

@@ -1304,7 +1304,7 @@ static void gen_BLSI(DisasContext *s, X86DecodedInsn *decode)
     /* input in T1, which is ready for prepare_update2_cc  */
     tcg_gen_neg_tl(s->T0, s->T1);
     tcg_gen_and_tl(s->T0, s->T0, s->T1);
-    prepare_update2_cc(decode, s, CC_OP_BMILGB + ot);
+    prepare_update2_cc(decode, s, CC_OP_BLSIB + ot);
 }
 
 static void gen_BLSMSK(DisasContext *s, X86DecodedInsn *decode)

target/i386/tcg/seg_helper.c

@@ -378,7 +378,7 @@ static int switch_tss_ra(CPUX86State *env, int tss_selector,
 
     /* X86Access avoids memory exceptions during the task switch */
     mmu_index = cpu_mmu_index_kernel(env);
-    access_prepare_mmu(&old, env, env->tr.base, old_tss_limit_max,
+    access_prepare_mmu(&old, env, env->tr.base, old_tss_limit_max + 1,
                        MMU_DATA_STORE, mmu_index, retaddr);
 
     if (source == SWITCH_TSS_CALL) {
@@ -386,7 +386,8 @@ static int switch_tss_ra(CPUX86State *env, int tss_selector,
         probe_access(env, tss_base, 2, MMU_DATA_STORE,
                      mmu_index, retaddr);
     }
-    access_prepare_mmu(&new, env, tss_base, tss_limit,
+    /* While true tss_limit may be larger, we don't access the iopb here. */
+    access_prepare_mmu(&new, env, tss_base, tss_limit_max + 1,
                        MMU_DATA_LOAD, mmu_index, retaddr);
 
     /* save the current state in the old TSS */

target/i386/tcg/translate.c

@@ -304,6 +304,7 @@ static const uint8_t cc_op_live[CC_OP_NB] = {
     [CC_OP_SHLB ... CC_OP_SHLQ] = USES_CC_DST | USES_CC_SRC,
     [CC_OP_SARB ... CC_OP_SARQ] = USES_CC_DST | USES_CC_SRC,
     [CC_OP_BMILGB ... CC_OP_BMILGQ] = USES_CC_DST | USES_CC_SRC,
+    [CC_OP_BLSIB ... CC_OP_BLSIQ] = USES_CC_DST | USES_CC_SRC,
     [CC_OP_ADCX] = USES_CC_DST | USES_CC_SRC,
     [CC_OP_ADOX] = USES_CC_SRC | USES_CC_SRC2,
     [CC_OP_ADCOX] = USES_CC_DST | USES_CC_SRC | USES_CC_SRC2,
@@ -865,6 +866,18 @@ static CCPrepare gen_prepare_sign_nz(TCGv src, MemOp size)
     }
 }
 
+static CCPrepare gen_prepare_val_nz(TCGv src, MemOp size, bool eqz)
+{
+    if (size == MO_TL) {
+        return (CCPrepare) { .cond = eqz ? TCG_COND_EQ : TCG_COND_NE,
+                             .reg = src };
+    } else {
+        return (CCPrepare) { .cond = eqz ? TCG_COND_TSTEQ : TCG_COND_TSTNE,
+                             .imm = MAKE_64BIT_MASK(0, 8 << size),
+                             .reg = src };
+    }
+}
+
 /* compute eflags.C, trying to store it in reg if not NULL */
 static CCPrepare gen_prepare_eflags_c(DisasContext *s, TCGv reg)
 {
@@ -908,8 +921,11 @@ static CCPrepare gen_prepare_eflags_c(DisasContext *s, TCGv reg)
 
     case CC_OP_BMILGB ... CC_OP_BMILGQ:
         size = s->cc_op - CC_OP_BMILGB;
-        gen_ext_tl(cpu_cc_src, cpu_cc_src, size, false);
+        return gen_prepare_val_nz(cpu_cc_src, size, true);
-        return (CCPrepare) { .cond = TCG_COND_EQ, .reg = cpu_cc_src };
+
+    case CC_OP_BLSIB ... CC_OP_BLSIQ:
+        size = s->cc_op - CC_OP_BLSIB;
+        return gen_prepare_val_nz(cpu_cc_src, size, false);
 
     case CC_OP_ADCX:
     case CC_OP_ADCOX:
@@ -1006,12 +1022,7 @@ static CCPrepare gen_prepare_eflags_z(DisasContext *s, TCGv reg)
     default:
         {
             MemOp size = (s->cc_op - CC_OP_ADDB) & 3;
-            if (size == MO_TL) {
+            return gen_prepare_val_nz(cpu_cc_dst, size, true);
-                return (CCPrepare) { .cond = TCG_COND_EQ, .reg = cpu_cc_dst };
-            } else {
-                return (CCPrepare) { .cond = TCG_COND_TSTEQ, .reg = cpu_cc_dst,
-                                     .imm = (1ull << (8 << size)) - 1 };
-            }
         }
     }
 }

tests/tcg/x86_64/Makefile.target

@@ -16,6 +16,7 @@ X86_64_TESTS += noexec
 X86_64_TESTS += cmpxchg
 X86_64_TESTS += adox
 X86_64_TESTS += test-1648
+X86_64_TESTS += test-2175
 TESTS=$(MULTIARCH_TESTS) $(X86_64_TESTS) test-x86_64
 else
 TESTS=$(MULTIARCH_TESTS)

tests/tcg/x86_64/test-2175.c

@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* See https://gitlab.com/qemu-project/qemu/-/issues/2185 */
+
+#include <assert.h>
+
+int test_setc(unsigned int x, unsigned int y)
+{
+    asm("blsi %1, %0; setc %b0" : "+r"(x) : "r"(y));
+    return (unsigned char)x;
+}
+
+int test_pushf(unsigned int x, unsigned int y)
+{
+    asm("blsi %1, %0; pushf; pop %q0" : "+r"(x) : "r"(y));
+    return x & 1;
+}
+
+int main()
+{
+    assert(test_setc(1, 0xedbf530a));
+    assert(test_pushf(1, 0xedbf530a));
+    return 0;
+}
+