Hi Christophe,

quoted

          max_len = DAWR_MAX_LEN;
          /* DAWR region can't cross 512 bytes boundary */
-        if ((start_addr >> 9) != (end_addr >> 9))
+        if ((start_addr >> 9) != ((end_addr - 1) >> 9))

What about:
     if (ALIGN(start_addr, SZ_512M) != ALIGN(end - 1, SZ_512M))

ok.

quoted

              return -EINVAL;
      } else if (IS_ENABLED(CONFIG_PPC_8xx)) {
          /* 8xx can setup a range without limitation */

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index aab82ab80dfa..06679adac447 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c

@@ -800,12 +800,12 @@ static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)

      unsigned long lctrl1 = LCTRL1_CTE_GT | LCTRL1_CTF_LT | LCTRL1_CRWE_RW |
                     LCTRL1_CRWF_RW;
      unsigned long lctrl2 = LCTRL2_LW0EN | LCTRL2_LW0LADC | LCTRL2_SLW0EN;
-    unsigned long start_addr = brk->address & ~HW_BREAKPOINT_ALIGN;
-    unsigned long end_addr = (brk->address + brk->len - 1) | HW_BREAKPOINT_ALIGN;
+    unsigned long start_addr = ALIGN_DOWN(brk->address, HW_BREAKPOINT_SIZE);
+    unsigned long end_addr = ALIGN(brk->address + brk->len, HW_BREAKPOINT_SIZE);
      if (start_addr == 0)
          lctrl2 |= LCTRL2_LW0LA_F;
-    else if (end_addr == ~0U)
+    else if (end_addr - 1 == ~0U)

What about:
     else if (end_addr == 0)

That's better.

Thanks,
Ravi