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[PATCH] x86/HPET: avoid an indirect call


  • To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Tue, 16 Jan 2024 17:56:10 +0100
  • Autocrypt: addr=jbeulich@xxxxxxxx; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL
  • Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Tue, 16 Jan 2024 16:56:17 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

When this code was written, indirect branches still weren't considered
much of a problem (besides being a little slower). Instead of a function
pointer, pass a boolean to _disable_pit_irq(), thus allowing to
eliminate two ENDBR (one of them in .text).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/hpet.c
+++ b/xen/arch/x86/hpet.c
@@ -563,7 +563,7 @@ static void cf_check handle_rtc_once(uin
     }
 }
 
-void __init cf_check hpet_broadcast_init(void)
+void __init hpet_broadcast_init(void)
 {
     u64 hpet_rate = hpet_setup();
     u32 hpet_id, cfg;
@@ -634,7 +634,7 @@ void __init cf_check hpet_broadcast_init
         hpet_events->flags = HPET_EVT_LEGACY;
 }
 
-void cf_check hpet_broadcast_resume(void)
+void hpet_broadcast_resume(void)
 {
     u32 cfg;
     unsigned int i, n;
--- a/xen/arch/x86/include/asm/hpet.h
+++ b/xen/arch/x86/include/asm/hpet.h
@@ -89,8 +89,8 @@ void hpet_disable_legacy_replacement_mod
  * Temporarily use an HPET event counter for timer interrupt handling,
  * rather than using the LAPIC timer. Used for Cx state entry.
  */
-void cf_check hpet_broadcast_init(void);
-void cf_check hpet_broadcast_resume(void);
+void hpet_broadcast_init(void);
+void hpet_broadcast_resume(void);
 void cf_check hpet_broadcast_enter(void);
 void cf_check hpet_broadcast_exit(void);
 int hpet_broadcast_is_available(void);
--- a/xen/arch/x86/time.c
+++ b/xen/arch/x86/time.c
@@ -2427,7 +2427,7 @@ void __init early_time_init(void)
 }
 
 /* keep pit enabled for pit_broadcast working while cpuidle enabled */
-static int _disable_pit_irq(void(*hpet_broadcast_setup)(void))
+static int _disable_pit_irq(bool init)
 {
     int ret = 1;
 
@@ -2442,13 +2442,13 @@ static int _disable_pit_irq(void(*hpet_b
      */
     if ( cpuidle_using_deep_cstate() && !boot_cpu_has(X86_FEATURE_ARAT) )
     {
-        hpet_broadcast_setup();
+        init ? hpet_broadcast_init() : hpet_broadcast_resume();
         if ( !hpet_broadcast_is_available() )
         {
             if ( xen_cpuidle > 0 )
             {
-                printk("%ps() failed, turning to PIT broadcast\n",
-                       hpet_broadcast_setup);
+                printk("hpet_broadcast_%s() failed, turning to PIT 
broadcast\n",
+                       init ? "init" : "resume");
                 return -1;
             }
             ret = 0;
@@ -2465,7 +2465,7 @@ static int _disable_pit_irq(void(*hpet_b
 
 static int __init cf_check disable_pit_irq(void)
 {
-    if ( !_disable_pit_irq(hpet_broadcast_init) )
+    if ( !_disable_pit_irq(true) )
     {
         xen_cpuidle = 0;
         printk("CPUIDLE: disabled due to no HPET. "
@@ -2526,7 +2526,7 @@ int time_resume(void)
 
     resume_platform_timer();
 
-    if ( !_disable_pit_irq(hpet_broadcast_resume) )
+    if ( !_disable_pit_irq(false) )
         BUG();
 
     init_percpu_time();



 


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