sandbox: Enhance map_to_sysmem() to handle foreign pointers

At present map_sysmem() maps an address into the sandbox RAM buffer,
return a pointer, while map_to_sysmem() goes the other way.

The mapping is currently just 1:1 since a case was not found where a more
flexible mapping was needed. PCI does have a separate and more complex
mapping, but uses its own mechanism.

However this arrange cannot handle one important case, which is where a
test declares a stack variable and passes a pointer to it into a U-Boot
function which uses map_to_sysmem() to turn it into a address. Since the
pointer is not inside emulated DRAM, this will fail.

Add a mapping feature which can handle any such pointer, mapping it to a
simple tag value which can be passed around in U-Boot as an address.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/arch/sandbox/cpu/cpu.c b/arch/sandbox/cpu/cpu.c
index cde0b05..e523223 100644 (file)
--- a/arch/sandbox/cpu/cpu.c
+++ b/arch/sandbox/cpu/cpu.c
@@ -57,14 +57,104 @@ int cleanup_before_linux_select(int flags)
        return 0;
 }
 
+/**
+ * is_in_sandbox_mem() - Checks if a pointer is within sandbox's emulated DRAM
+ *
+ * This provides a way to check if a pointer is owned by sandbox (and is within
+ * its RAM) or not. Sometimes pointers come from a test which conceptually runs
+ * output sandbox, potentially with direct access to the C-library malloc()
+ * function, or the sandbox stack (which is not actually within the emulated
+ * DRAM.
+ *
+ * Such pointers obviously cannot be mapped into sandbox's DRAM, so we must
+ * detect them an process them separately, by recording a mapping to a tag,
+ * which we can use to map back to the pointer later.
+ *
+ * @ptr: Pointer to check
+ * @return true if this is within sandbox emulated DRAM, false if not
+ */
+static bool is_in_sandbox_mem(const void *ptr)
+{
+       return (const uint8_t *)ptr >= gd->arch.ram_buf &&
+               (const uint8_t *)ptr < gd->arch.ram_buf + gd->ram_size;
+}
+
+/**
+ * phys_to_virt() - Converts a sandbox RAM address to a pointer
+ *
+ * Sandbox uses U-Boot addresses from 0 to the size of DRAM. These index into
+ * the emulated DRAM buffer used by sandbox. This function converts such an
+ * address to a pointer into this buffer, which can be used to access the
+ * memory.
+ *
+ * If the address is outside this range, it is assumed to be a tag
+ */
 void *phys_to_virt(phys_addr_t paddr)
 {
-       return (void *)(gd->arch.ram_buf + paddr);
+       struct sandbox_mapmem_entry *mentry;
+       struct sandbox_state *state;
+
+       /* If the address is within emulated DRAM, calculate the value */
+       if (paddr < gd->ram_size)
+               return (void *)(gd->arch.ram_buf + paddr);
+
+       /*
+        * Otherwise search out list of tags for the correct pointer previously
+        * created by map_to_sysmem()
+        */
+       state = state_get_current();
+       list_for_each_entry(mentry, &state->mapmem_head, sibling_node) {
+               if (mentry->tag == paddr) {
+                       printf("%s: Used map from %lx to %p\n", __func__,
+                              (ulong)paddr, mentry->ptr);
+                       return mentry->ptr;
+               }
+       }
+
+       printf("%s: Cannot map sandbox address %lx (SDRAM from 0 to %lx)\n",
+              __func__, (ulong)paddr, (ulong)gd->ram_size);
+       os_abort();
+
+       /* Not reached */
+       return NULL;
+}
+
+struct sandbox_mapmem_entry *find_tag(const void *ptr)
+{
+       struct sandbox_mapmem_entry *mentry;
+       struct sandbox_state *state = state_get_current();
+
+       list_for_each_entry(mentry, &state->mapmem_head, sibling_node) {
+               if (mentry->ptr == ptr) {
+                       debug("%s: Used map from %p to %lx\n", __func__, ptr,
+                             mentry->tag);
+                       return mentry;
+               }
+       }
+       return NULL;
 }
 
-phys_addr_t virt_to_phys(void *vaddr)
+phys_addr_t virt_to_phys(void *ptr)
 {
-       return (phys_addr_t)((uint8_t *)vaddr - gd->arch.ram_buf);
+       struct sandbox_mapmem_entry *mentry;
+
+       /*
+        * If it is in emulated RAM, don't bother looking for a tag. Just
+        * calculate the pointer using the provides offset into the RAM buffer.
+        */
+       if (is_in_sandbox_mem(ptr))
+               return (phys_addr_t)((uint8_t *)ptr - gd->arch.ram_buf);
+
+       mentry = find_tag(ptr);
+       if (!mentry) {
+               /* Abort so that gdb can be used here */
+               printf("%s: Cannot map sandbox address %p (SDRAM from 0 to %lx)\n",
+                      __func__, ptr, (ulong)gd->ram_size);
+               os_abort();
+       }
+       printf("%s: Used map from %p to %lx\n", __func__, ptr, mentry->tag);
+
+       return mentry->tag;
 }
 
 void *map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags)
@@ -87,24 +177,57 @@ void *map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags)
        return phys_to_virt(paddr);
 }
 
-void unmap_physmem(const void *vaddr, unsigned long flags)
+void unmap_physmem(const void *ptr, unsigned long flags)
 {
 #ifdef CONFIG_PCI
        if (map_dev) {
-               pci_unmap_physmem(vaddr, map_len, map_dev);
+               pci_unmap_physmem(ptr, map_len, map_dev);
                map_dev = NULL;
        }
 #endif
 }
 
-void sandbox_set_enable_pci_map(int enable)
+phys_addr_t map_to_sysmem(const void *ptr)
 {
-       enable_pci_map = enable;
+       struct sandbox_mapmem_entry *mentry;
+
+       /*
+        * If it is in emulated RAM, don't bother creating a tag. Just return
+        * the offset into the RAM buffer.
+        */
+       if (is_in_sandbox_mem(ptr))
+               return (u8 *)ptr - gd->arch.ram_buf;
+
+       /*
+        * See if there is an existing tag with this pointer. If not, set up a
+        * new one.
+        */
+       mentry = find_tag(ptr);
+       if (!mentry) {
+               struct sandbox_state *state = state_get_current();
+
+               mentry = malloc(sizeof(*mentry));
+               if (!mentry) {
+                       printf("%s: Error: Out of memory\n", __func__);
+                       os_exit(ENOMEM);
+               }
+               mentry->tag = state->next_tag++;
+               mentry->ptr = (void *)ptr;
+               list_add_tail(&mentry->sibling_node, &state->mapmem_head);
+               debug("%s: Added map from %p to %lx\n", __func__, ptr,
+                     (ulong)mentry->tag);
+       }
+
+       /*
+        * Return the tag as the address to use. A later call to map_sysmem()
+        * will return ptr
+        */
+       return mentry->tag;
 }
 
-phys_addr_t map_to_sysmem(const void *ptr)
+void sandbox_set_enable_pci_map(int enable)
 {
-       return (u8 *)ptr - gd->arch.ram_buf;
+       enable_pci_map = enable;
 }
 
 void flush_dcache_range(unsigned long start, unsigned long stop)

diff --git a/arch/sandbox/cpu/state.c b/arch/sandbox/cpu/state.c
index cc50819..04a11fe 100644 (file)
--- a/arch/sandbox/cpu/state.c
+++ b/arch/sandbox/cpu/state.c
@@ -359,6 +359,14 @@ void state_reset_for_test(struct sandbox_state *state)
 
        memset(&state->wdt, '\0', sizeof(state->wdt));
        memset(state->spi, '\0', sizeof(state->spi));
+
+       /*
+        * Set up the memory tag list. Use the top of emulated SDRAM for the
+        * first tag number, since that address offset is outside the legal
+        * range, and can be assumed to be a tag.
+        */
+       INIT_LIST_HEAD(&state->mapmem_head);
+       state->next_tag = state->ram_size;
 }
 
 int state_init(void)

diff --git a/arch/sandbox/include/asm/state.h b/arch/sandbox/include/asm/state.h
index 7ed4b51..a612ce8 100644 (file)
--- a/arch/sandbox/include/asm/state.h
+++ b/arch/sandbox/include/asm/state.h
@@ -9,6 +9,7 @@
 #include <config.h>
 #include <sysreset.h>
 #include <stdbool.h>
+#include <linux/list.h>
 #include <linux/stringify.h>
 
 /**
@@ -45,6 +46,23 @@ struct sandbox_wdt_info {
        bool running;
 };
 
+/**
+ * struct sandbox_mapmem_entry - maps pointers to/from U-Boot addresses
+ *
+ * When map_to_sysmem() is called with an address outside sandbox's emulated
+ * RAM, a record is created with a tag that can be used to reference that
+ * pointer. When map_sysmem() is called later with that tag, the pointer will
+ * 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)
+ * @ptr: Associated pointer for that tag
+ */
+struct sandbox_mapmem_entry {
+       ulong tag;
+       void *ptr;
+       struct list_head sibling_node;
+};
+
 /* The complete state of the test system */
 struct sandbox_state {
        const char *cmd;                /* Command to execute */
@@ -78,6 +96,9 @@ struct sandbox_state {
 
        /* Information about Watchdog */
        struct sandbox_wdt_info wdt;
+
+       ulong next_tag;                 /* Next address tag to allocate */
+       struct list_head mapmem_head;   /* struct sandbox_mapmem_entry */
 };
 
 /* Minimum space we guarantee in the state FDT when calling read/write*/