From: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Date: Mon, 12 Aug 2024 14:13:18 +0000 (+0200)
Subject: kern/riscv/efi/init: Use time register in grub_efi_get_time_ms()
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c5ae124e11f28f637cbd38cb4d6c1b9817baa135;p=thirdparty%2Fgrub.git

kern/riscv/efi/init: Use time register in grub_efi_get_time_ms()

The cycle register is not guaranteed to count at constant frequency.
If it is counting at all depends on the state the performance monitoring
unit. Use the time register to measure time.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---

diff --git a/grub-core/kern/riscv/efi/init.c b/grub-core/kern/riscv/efi/init.c
index 38795fe67..0d7de4f54 100644
--- a/grub-core/kern/riscv/efi/init.c
+++ b/grub-core/kern/riscv/efi/init.c
@@ -33,16 +33,15 @@ grub_efi_get_time_ms (void)
   grub_uint64_t tmr;
 
 #if __riscv_xlen == 64
-  asm volatile ("rdcycle %0" : "=r" (tmr));
+  asm volatile ("rdtime %0" : "=r"(tmr));
 #else
   grub_uint32_t lo, hi, tmp;
-  asm volatile (
-    "1:\n"
-    "rdcycleh %0\n"
-    "rdcycle %1\n"
-    "rdcycleh %2\n"
-    "bne %0, %2, 1b"
-    : "=&r" (hi), "=&r" (lo), "=&r" (tmp));
+  asm volatile ("1:\n"
+                "rdtimeh %0\n"
+                "rdtime %1\n"
+                "rdtimeh %2\n"
+                "bne %0, %2, 1b"
+                : "=&r" (hi), "=&r" (lo), "=&r" (tmp));
   tmr = ((grub_uint64_t)hi << 32) | lo;
 #endif