[PATCH 2/3] x86/EFI: replace ebmalloc()

[Jan Beulich <jbeulich@xxxxxxxx>]

Use the new brk_alloc() instead, with ebmalloc() merely being a thin
wrapper.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
I'm not quite certain whether we ought to permit non-page-granular
reservations. The in-memory image being somewhat larger due to possibly
excessive padding isn't really a big problem, I think.

--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -262,7 +262,7 @@ quiet_cmd_obj_init_o = INIT_O  $@
 define cmd_obj_init_o
     $(OBJDUMP) -h $< | while read idx name sz rest; do \
         case "$$name" in \
-        .*.local) ;; \
+        .*.local|.bss..brk*) ;; \
         .text|.text.*|.data|.data.*|.bss|.bss.*) \
             test $$(echo $$sz | sed 's,00*,0,') != 0 || continue; \
             echo "Error: size of $<:$$name is 0x$$sz" >&2; \
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -10,6 +10,7 @@
 #include <xen/vga.h>
 
 #include <asm/boot-helpers.h>
+#include <asm/brk.h>
 #include <asm/e820.h>
 #include <asm/edd.h>
 #include <asm/microcode.h>
@@ -119,6 +120,18 @@ static void __init relocate_trampoline(u
     reloc_trampoline64();
 }
 
+DEFINE_BRK(efi, MB(1));
+
+static void *__init ebmalloc(size_t size)
+{
+    void *ptr = brk_alloc(size);
+
+    if ( !ptr )
+        blexit(L"Out of BRK memory\r\n");
+
+    return ptr;
+}
+
 static void __init place_string(u32 *addr, const char *s)
 {
     char *alloc = NULL;
--- a/xen/arch/x86/efi/stub.c
+++ b/xen/arch/x86/efi/stub.c
@@ -41,12 +41,4 @@ void __init noreturn efi_multiboot2(EFI_
 
 void __init efi_init_memory(void) { }
 
-bool efi_boot_mem_unused(unsigned long *start, unsigned long *end)
-{
-    /* FIXME: Simplify once the call here with two NULLs goes away. */
-    if ( start || end )
-        *start = *end = (unsigned long)_end;
-    return false;
-}
-
 void efi_update_l4_pgtable(unsigned int l4idx, l4_pgentry_t l4e) { }
--- a/xen/arch/x86/include/asm/brk.h
+++ b/xen/arch/x86/include/asm/brk.h
@@ -2,6 +2,10 @@
 
 #include <xen/types.h>
 
+#define DEFINE_BRK(var, size) \
+    static char __section(".bss..brk.page_aligned") __aligned(PAGE_SIZE) \
+        __used var ## _brk_[size]
+
 void *brk_alloc(size_t size);
 unsigned long brk_get_unused_start(void);
 void brk_free_unused(void);
--- a/xen/arch/x86/include/asm/setup.h
+++ b/xen/arch/x86/include/asm/setup.h
@@ -9,6 +9,8 @@ extern const char __2M_rodata_start[], _
 extern char __2M_init_start[], __2M_init_end[];
 extern char __2M_rwdata_start[], __2M_rwdata_end[];
 
+extern unsigned long brk_end;
+
 extern unsigned long xenheap_initial_phys_start;
 extern uint64_t boot_tsc_stamp;
 
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -31,6 +31,7 @@
 #include <asm/alternative.h>
 #include <asm/apic.h>
 #include <asm/bootinfo.h>
+#include <asm/brk.h>
 #include <asm/bzimage.h>
 #include <asm/cpu-policy.h>
 #include <asm/e820.h>
@@ -163,6 +164,8 @@ cpumask_t __read_mostly cpu_present_map;
 
 unsigned long __read_mostly xen_phys_start;
 
+unsigned long __ro_after_init brk_end;
+
 /* Only used in asm code and within this source file */
 char asmlinkage __section(".init.bss.stack_aligned") __aligned(STACK_SIZE)
     cpu0_stack[STACK_SIZE];
@@ -1109,7 +1112,6 @@ void asmlinkage __init noreturn __start_
     struct boot_info *bi;
     unsigned long nr_pages, raw_max_page;
     int i, j, bytes = 0;
-    unsigned long eb_start, eb_end;
     bool acpi_boot_table_init_done = false, relocated = false;
     bool vm_init_done = false;
     int ret;
@@ -1473,7 +1475,7 @@ void asmlinkage __init noreturn __start_
         /*
          * This needs to remain in sync with remove_xen_ranges() and the
          * respective reserve_e820_ram() invocation below. No need to
-         * query efi_boot_mem_unused() here, though.
+         * query brk_get_unused_start() here, though.
          */
         xen->start = virt_to_maddr(_stext);
         xen->size  = __2M_rwdata_end - _stext;
@@ -1616,18 +1618,11 @@ void asmlinkage __init noreturn __start_
     if ( !xen_phys_start )
         panic("Not enough memory to relocate Xen\n");
 
-    /* FIXME: Putting a hole in .bss would shatter the large page mapping. */
-    if ( using_2M_mapping() )
-        efi_boot_mem_unused(NULL, NULL);
-
     /* This needs to remain in sync with remove_xen_ranges(). */
-    if ( efi_boot_mem_unused(&eb_start, &eb_end) )
-    {
-        reserve_e820_ram(&boot_e820, __pa(_stext), __pa(eb_start));
-        reserve_e820_ram(&boot_e820, __pa(eb_end), __pa(__2M_rwdata_end));
-    }
-    else
-        reserve_e820_ram(&boot_e820, __pa(_stext), __pa(__2M_rwdata_end));
+    brk_end = brk_get_unused_start();
+    if ( using_2M_mapping() )
+        brk_end = PAGE_ALIGN_2M(brk_end);
+    reserve_e820_ram(&boot_e820, __pa(_stext), __pa(brk_end));
 
     /* Late kexec reservation (dynamic start address). */
     kexec_reserve_area();
@@ -2231,7 +2226,6 @@ __initcall(init_xen_cap_info);
 
 int __hwdom_init remove_xen_ranges(struct rangeset *r)
 {
-    paddr_t start, end;
     int rc;
 
     /* S3 resume code (and other real mode trampoline code) */
@@ -2253,26 +2247,10 @@ int __hwdom_init remove_xen_ranges(struc
         return rc;
 
     /* hypervisor .data + .bss */
-    if ( efi_boot_mem_unused(&start, &end) )
-    {
-        ASSERT(__pa(start) >= __pa(&__2M_rwdata_start));
-        rc = rangeset_remove_range(r, PFN_DOWN(__pa(&__2M_rwdata_start)),
-                                   PFN_DOWN(__pa(start) - 1));
-        if ( rc )
-            return rc;
-        ASSERT(__pa(end) <= __pa(&__2M_rwdata_end));
-        rc = rangeset_remove_range(r, PFN_DOWN(__pa(end)),
-                                   PFN_DOWN(__pa(&__2M_rwdata_end) - 1));
-        if ( rc )
-            return rc;
-    }
-    else
-    {
-        rc = rangeset_remove_range(r, PFN_DOWN(__pa(&__2M_rwdata_start)),
-                                   PFN_DOWN(__pa(&__2M_rwdata_end) - 1));
-        if ( rc )
-            return rc;
-    }
+    rc = rangeset_remove_range(r, PFN_DOWN(__pa(&__2M_rwdata_start)),
+                               PFN_DOWN(__pa(brk_end) - 1));
+    if ( rc )
+        return rc;
 
     return 0;
 }
--- a/xen/arch/x86/tboot.c
+++ b/xen/arch/x86/tboot.c
@@ -321,8 +321,6 @@ void tboot_shutdown(uint32_t shutdown_ty
     /* if this is S3 then set regions to MAC */
     if ( shutdown_type == TB_SHUTDOWN_S3 )
     {
-        unsigned long s, e;
-
         /*
          * Xen regions for tboot to MAC. This needs to remain in sync with
          * remove_xen_ranges().
@@ -336,16 +334,8 @@ void tboot_shutdown(uint32_t shutdown_ty
         g_tboot_shared->mac_regions[1].size = __2M_rodata_end - _stext;
         /* hypervisor .data + .bss */
         g_tboot_shared->mac_regions[2].start = 
(uint64_t)__pa(&__2M_rwdata_start);
-        g_tboot_shared->mac_regions[2].size = __2M_rwdata_end - 
__2M_rwdata_start;
-        if ( efi_boot_mem_unused(&s, &e) )
-        {
-            g_tboot_shared->mac_regions[2].size =
-                s - (unsigned long)__2M_rwdata_start;
-            g_tboot_shared->mac_regions[3].start = __pa(e);
-            g_tboot_shared->mac_regions[3].size =
-                (unsigned long)__2M_rwdata_end - e;
-            g_tboot_shared->num_mac_regions = 4;
-        }
+        g_tboot_shared->mac_regions[2].size =
+            brk_end - (unsigned long)__2M_rwdata_start;
 
         /*
          * MAC domains and other Xen memory
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1788,8 +1788,6 @@ void __init efi_init_memory(void)
         pte_attr_t prot;
     } *extra, *extra_head = NULL;
 
-    free_ebmalloc_unused_mem();
-
     if ( !efi_enabled(EFI_BOOT) )
         return;
 
--- a/xen/common/efi/ebmalloc.c
+++ /dev/null
@@ -1,74 +0,0 @@
-#include "efi.h"
-#include <xen/init.h>
-#include <xen/mm.h>
-
-#ifdef CONFIG_ARM
-/*
- * TODO: Enable EFI boot allocator on ARM.
- * This code can be common for x86 and ARM.
- * Things TODO on ARM before enabling ebmalloc:
- *   - estimate required EBMALLOC_SIZE value,
- *   - where (in which section) ebmalloc_mem[] should live; if in
- *     .bss.page_aligned, as it is right now, then whole BSS zeroing
- *     have to be disabled in xen/arch/arm/arm64/head.S; though BSS
- *     should be initialized somehow before use of variables living there,
- *   - use ebmalloc() in ARM/common EFI boot code,
- *   - call free_ebmalloc_unused_mem() somewhere in init code.
- */
-#define EBMALLOC_SIZE  MB(0)
-#else
-#define EBMALLOC_SIZE  MB(1)
-#endif
-
-static char __section(".bss.page_aligned") __aligned(PAGE_SIZE)
-    ebmalloc_mem[EBMALLOC_SIZE];
-static unsigned long __read_mostly ebmalloc_allocated;
-
-/* EFI boot allocator. */
-void __init *ebmalloc(size_t size)
-{
-    void *ptr = ebmalloc_mem + ebmalloc_allocated;
-
-    ebmalloc_allocated += ROUNDUP(size, sizeof(void *));
-
-    if ( ebmalloc_allocated > sizeof(ebmalloc_mem) )
-        blexit(L"Out of static memory\r\n");
-
-    return ptr;
-}
-
-bool efi_boot_mem_unused(unsigned long *start, unsigned long *end)
-{
-    /* FIXME: Drop once the call here with two NULLs goes away. */
-    if ( !start && !end )
-    {
-        ebmalloc_allocated = sizeof(ebmalloc_mem);
-        return false;
-    }
-
-    *start = (unsigned long)ebmalloc_mem + PAGE_ALIGN(ebmalloc_allocated);
-    *end = (unsigned long)ebmalloc_mem + sizeof(ebmalloc_mem);
-
-    return *start < *end;
-}
-
-void __init free_ebmalloc_unused_mem(void)
-{
-    unsigned long start, end;
-
-    if ( !efi_boot_mem_unused(&start, &end) )
-        return;
-
-    destroy_xen_mappings(start, end);
-
-#ifdef CONFIG_X86
-    /*
-     * By reserving the space early in the E820 map, it gets freed way before
-     * we make it here. Don't free the range a 2nd time.
-     */
-#else
-    init_xenheap_pages(__pa(start), __pa(end));
-#endif
-
-    printk(XENLOG_INFO "Freed %lukB unused BSS memory\n", (end - start) >> 10);
-}
--- a/xen/common/efi/efi-common.mk
+++ b/xen/common/efi/efi-common.mk
@@ -1,4 +1,4 @@
-EFIOBJ-y := boot.init.o pe.init.o ebmalloc.o runtime.o
+EFIOBJ-y := boot.init.o pe.init.o runtime.o
 EFIOBJ-$(CONFIG_COMPAT) += compat.o
 
 CFLAGS-y += -fshort-wchar
--- a/xen/common/efi/efi.h
+++ b/xen/common/efi/efi.h
@@ -48,10 +48,6 @@ void noreturn blexit(const CHAR16 *str);
 
 const CHAR16 *wmemchr(const CHAR16 *s, CHAR16 c, UINTN n);
 
-/* EFI boot allocator. */
-void *ebmalloc(size_t size);
-void free_ebmalloc_unused_mem(void);
-
 const void *pe_find_section(const void *image, const UINTN image_size,
                             const CHAR16 *section_name, UINTN *size_out);
 
--- a/xen/include/xen/efi.h
+++ b/xen/include/xen/efi.h
@@ -39,7 +39,6 @@ static inline bool efi_enabled(unsigned
 extern bool efi_secure_boot;
 
 void efi_init_memory(void);
-bool efi_boot_mem_unused(unsigned long *start, unsigned long *end);
 bool efi_rs_using_pgtables(void);
 unsigned long efi_get_time(void);
 void efi_halt_system(void);