From f452e8f092b3e500ac955e44b7a3f1680d62d8f7 Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Sun, 1 Sep 2024 16:26:27 -0600
Subject: [PATCH] sandbox: Implement reference counting for address mapping
An address may be mapped twice and unmapped twice. Delete the mapping
only when the last user unmaps it.
Fix a missing comment while here.
Signed-off-by: Simon Glass <sjg@chromium.org>
---
arch/sandbox/cpu/cpu.c | 14 ++++++++++----
arch/sandbox/include/asm/state.h | 3 +++
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/arch/sandbox/cpu/cpu.c b/arch/sandbox/cpu/cpu.c
index 3e1c0dd583..51ce40e7f0 100644
--- a/arch/sandbox/cpu/cpu.c
+++ b/arch/sandbox/cpu/cpu.c
@@ -111,6 +111,7 @@ void *phys_to_virt(phys_addr_t paddr)
if (mentry->tag == paddr) {
log_debug("Used map from %lx to %p\n", (ulong)paddr,
mentry->ptr);
+ mentry->refcnt++;
return mentry->ptr;
}
}
@@ -200,10 +201,12 @@ void unmap_physmem(const void *ptr, unsigned long flags)
mentry = find_tag(ptr);
if (mentry) {
- list_del(&mentry->sibling_node);
- log_debug("Removed map from %p to %lx\n", ptr,
- (ulong)mentry->tag);
- free(mentry);
+ if (!--mentry->refcnt) {
+ list_del(&mentry->sibling_node);
+ log_debug("Removed map from %p to %lx\n", ptr,
+ (ulong)mentry->tag);
+ free(mentry);
+ }
} else {
log_warning("Address not mapped: %p\n", ptr);
}
@@ -235,11 +238,14 @@ phys_addr_t map_to_sysmem(const void *ptr)
}
mentry->tag = state->next_tag++;
mentry->ptr = (void *)ptr;
+ mentry->refcnt = 0;
list_add_tail(&mentry->sibling_node, &state->mapmem_head);
log_debug("Added map from %p to %lx\n", ptr,
(ulong)mentry->tag);
}
+ mentry->refcnt++;
+
/*
* Return the tag as the address to use. A later call to map_sysmem()
* will return ptr
diff --git a/arch/sandbox/include/asm/state.h b/arch/sandbox/include/asm/state.h
index 6b50473ed4..e7dc01759e 100644
--- a/arch/sandbox/include/asm/state.h
+++ b/arch/sandbox/include/asm/state.h
@@ -53,10 +53,13 @@ struct sandbox_wdt_info {
* be returned, just as it would for a normal sandbox address.
*
* @tag: Address tag (a value which U-Boot uses to refer to the address)
+ * @refcnt: Number of references to this tag
* @ptr: Associated pointer for that tag
+ * @sibling_node: Next node
*/
struct sandbox_mapmem_entry {
ulong tag;
+ uint refcnt;
void *ptr;
struct list_head sibling_node;
};
--
2.39.5