[Valgrind-developers] [valgrind] s390: Add VEX_HWCAPS_S390X_MRMM

[Florian K. <fk...@so...>]

https://sourceware.org/cgit/valgrind/commit/?id=f86f6e5a157c533d69558dc629c13ab3f6c75309

commit f86f6e5a157c533d69558dc629c13ab3f6c75309
Author: Florian Krohm <fl...@ei...>
Date:   Fri Mar 13 22:36:23 2026 +0000

    s390: Add VEX_HWCAPS_S390X_MRMM
    
    In b640fa64b8 z196 was chosen to be the minimum required machine
    model. That machine provides a list of facilities (aka hardware
    capabilities). But show_hwcaps_s390x did not show them.
    This patch adds VEX_HWCAPS_S390X_MRMM (where MRMM means Minimum Required
    Machine Model) which represents all hardware capabilities of that machine.
    
    Also: drop the "s390x" prefix in show_hwcaps_s390x because "s390x" isn't
    a hardware capability.
    
    When running with -d hardware capabilities are shown like so:
    --1085356:1:    main ... arch = S390X, hwcaps = z196-vx-msa5-mi2-lsc2-vxe-dflt-vxe2-vxd-msa8-msa9-msa12

Diff:
---
 VEX/priv/main_main.c  | 9 ++++-----
 VEX/pub/libvex.h      | 4 +++-
 coregrind/m_machine.c | 3 +++
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/VEX/priv/main_main.c b/VEX/priv/main_main.c
index e2f20fc31c..b9a18a9d28 100644
--- a/VEX/priv/main_main.c
+++ b/VEX/priv/main_main.c
@@ -1899,11 +1899,11 @@ static const HChar* show_hwcaps_arm64 ( UInt hwcaps )
 
 static const HChar* show_hwcaps_s390x ( UInt hwcaps )
 {
-   static const HChar prefix[] = "s390x";
    static const struct {
       UInt  hwcaps_bit;
       HChar name[6];
    } hwcaps_list[] = {
+      { VEX_HWCAPS_S390X_MRMM,  "z196" },   /* always first */
       { VEX_HWCAPS_S390X_VX,    "vx" },
       { VEX_HWCAPS_S390X_MSA5,  "msa5" },
       { VEX_HWCAPS_S390X_MI2,   "mi2" },
@@ -1919,8 +1919,7 @@ static const HChar* show_hwcaps_s390x ( UInt hwcaps )
       { VEX_HWCAPS_S390X_MSA12, "msa12" },
    };
    /* Allocate a large enough buffer */
-   static HChar buf[sizeof prefix + 
-                    NUM_HWCAPS * (sizeof hwcaps_list[0].name + 1) + 1]; // '\0'
+   static HChar buf[NUM_HWCAPS * (sizeof hwcaps_list[0].name + 1) + 1]; // '\0'
 
    if (buf[0] != '\0') return buf;  /* already constructed */
 
@@ -1929,8 +1928,8 @@ static const HChar* show_hwcaps_s390x ( UInt hwcaps )
 
    hwcaps = VEX_HWCAPS_S390X(hwcaps);
 
-   p = buf + vex_sprintf(buf, "%s", prefix);
-   for (i = 0 ; i < NUM_HWCAPS; ++i) {
+   p = buf + vex_sprintf(buf, "%s", hwcaps_list[0].name);
+   for (i = 1 ; i < NUM_HWCAPS; ++i) {
       if (hwcaps & hwcaps_list[i].hwcaps_bit)
          p = p + vex_sprintf(p, "-%s", hwcaps_list[i].name);
    }
diff --git a/VEX/pub/libvex.h b/VEX/pub/libvex.h
index f22a264f81..fe41048d9e 100644
--- a/VEX/pub/libvex.h
+++ b/VEX/pub/libvex.h
@@ -176,6 +176,7 @@ typedef
 #define VEX_HWCAPS_S390X_MI3   (1 << 17) /* Miscellaneous-instruction-extensions facility 3 */
 #define VEX_HWCAPS_S390X_VXE3  (1 << 18) /* Vector-enhancements facility 3 */
 #define VEX_HWCAPS_S390X_MSA12 (1 << 19) /* Msg.-security-assist extension 12 */
+#define VEX_HWCAPS_S390X_MRMM  (1 << 19) /* Minimum required machine model */
 
 /* Special value representing all available s390x hwcaps */
 #define VEX_HWCAPS_S390X_ALL   (VEX_HWCAPS_S390X_VX    | \
@@ -191,7 +192,8 @@ typedef
                                 VEX_HWCAPS_S390X_MSA9  | \
                                 VEX_HWCAPS_S390X_MI3   | \
                                 VEX_HWCAPS_S390X_VXE3  | \
-                                VEX_HWCAPS_S390X_MSA12)
+                                VEX_HWCAPS_S390X_MSA12 | \
+                                VEX_HWCAPS_S390X_MRMM)
 
 #define VEX_HWCAPS_S390X(x)  ((x) & ~VEX_S390X_MODEL_MASK)
 #define VEX_S390X_MODEL(x)   ((x) &  VEX_S390X_MODEL_MASK)
diff --git a/coregrind/m_machine.c b/coregrind/m_machine.c
index 7676b4353e..c564a10b19 100644
--- a/coregrind/m_machine.c
+++ b/coregrind/m_machine.c
@@ -1535,6 +1535,8 @@ Bool VG_(machine_get_hwcaps)( void )
         identification yet. Keeping fingers crossed. */
      model = VG_(get_machine_model)();
 
+     /* When upgrading the minimum machine model do not forget to adjust
+        VEX_HWCAPS_S390X_MMM below and in main_main.c */
      if (model < VEX_S390X_MODEL_Z196) {
         VG_(message)(Vg_FailMsg, "Your machine is too old. "
                      "You need at least a z196 to run valgrind.\n");
@@ -1574,6 +1576,7 @@ Bool VG_(machine_get_hwcaps)( void )
         const UInt hwcaps_bit;
         const HChar name[6];   // may need adjustment for new facility names
      } fac_hwcaps[] = {
+        { True,    0,  VEX_HWCAPS_S390X_MRMM,  "Z196"  }, /* always first */
         { False, 129,  VEX_HWCAPS_S390X_VX,    "VX"    },
         { False,  57,  VEX_HWCAPS_S390X_MSA5,  "MSA5"  },
         { False,  58,  VEX_HWCAPS_S390X_MI2,   "MI2"   },