Re: [PATCH v6 08/17] arm64: hibernate: add trans_pgd public functions

quoted

+
+	memcpy(page, src_start, length);
+	__flush_icache_range((unsigned long)page, (unsigned long)page + length);
+
+	trans_pgd = (void *)get_safe_page(GFP_ATOMIC);
+	if (!trans_pgd)
+		return -ENOMEM;
+
+	rc = trans_pgd_map_page(trans_pgd, page, dst_addr,
+				PAGE_KERNEL_EXEC);
+	if (rc)
+		return rc;
+
 	/*
 	 * Load our new page tables. A strict BBM approach requires that we
 	 * ensure that TLBs are free of any entries that may overlap with the

(I suspect you are going to to duplicate this in the kexec code. Kexec has the same
pattern: instructions that have to be copied to do the relocation of the rest of memory)

Yes, the relocation function is also copied, but I do not see an easy
way to unify this particular code with kexec. We can discuss in kexec
part of this series what else can be unified with hibernate's code.

quoted

@@ -462,6 +476,24 @@ static int copy_page_tables(pgd_t *dst_pgdp, unsigned long start,

quoted

+int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
+			  unsigned long end)
+{
+	int rc;
+	pgd_t *trans_pgd = (pgd_t *)get_safe_page(GFP_ATOMIC);
+
+	if (!trans_pgd) {
+		pr_err("Failed to allocate memory for temporary page tables.\n");
+		return -ENOMEM;
+	}
+
+	rc = copy_page_tables(trans_pgd, start, end);
+	if (!rc)
+		*dst_pgdp = trans_pgd;

*dst_pgdp was already allocated in swsusp_arch_resume().

Good catch, I forgot to remove allocation from swsusp_arch_resume().

 

quoted

+
+	return rc;
+}
+
 /*
  * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
  *

@@ -488,7 +520,7 @@ int swsusp_arch_resume(void)
 		pr_err("Failed to allocate memory for temporary page tables.\n");
 		return -ENOMEM;
 	}

If the allocation moves into 'trans_pgd_create_copy()', please move the code just above
here (cut off by the diff) that allocates it in swsusp_arch_resume().

Its actually okay to leak memory like this, hibernate's allocator acts as a memory pool.
It either gets freed if we fail to resume, or vanishes when the resumed kernel takes over.

I did.

Reviewed-by: James Morse <james.morse@arm.com>

Thank you,
Pasha

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