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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 5/5] x86/boot: Do not use trampoline for no-real-mode boot paths
From: David Woodhouse <dwmw@xxxxxxxxxxxx>
Where booted from EFI or with no-real-mode, there is no need to stomp
on low memory with the 16-boot code. Instead, just go straight to
trampoline_protmode_entry() at its physical location within the Xen
image, having applied suitable relocations.
This means that the GDT has to be loaded with lgdtl because the 16-bit
lgdt instruction would drop the high 8 bits of the gdt_trampoline
address, causing failures if the Xen image was loaded above 16MiB.
For now, the boot code (including the EFI loader path) still determines
what the trampoline_phys address should be for the permanent 16-bit
trampoline (used for AP startup, and wakeup). But that trampoline is
now only relocated for that address and copied into low memory later,
from a relocate_trampoline() call made from __start_xen().
The permanent trampoline can't trivially use the 32-bit code in place in
its physical location in the Xen image, as idle_pg_table doesn't have a
full physical mapping. Fixing that is theoretically possible but it's
actually much simpler just to relocate the 32-bit code (again) into low
memory, alongside the 16-bit code for the permanent trampoline.
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
xen/arch/x86/acpi/power.c | 6 +--
xen/arch/x86/boot/head.S | 67 ++++++++++++++++------------------
xen/arch/x86/boot/trampoline.S | 32 ++++++++++++----
xen/arch/x86/cpu/common.c | 2 +-
xen/arch/x86/cpu/intel.c | 2 +-
xen/arch/x86/efi/efi-boot.h | 31 ++--------------
xen/arch/x86/setup.c | 46 +++++++++++++++++++++--
xen/arch/x86/smpboot.c | 6 +--
xen/arch/x86/tboot.c | 6 +--
xen/arch/x86/x86_64/mm.c | 2 +-
xen/include/asm-x86/acpi.h | 2 +-
xen/include/asm-x86/config.h | 12 +++---
12 files changed, 122 insertions(+), 92 deletions(-)
diff --git a/xen/arch/x86/acpi/power.c b/xen/arch/x86/acpi/power.c
index aecc754fdb..d2a355429e 100644
--- a/xen/arch/x86/acpi/power.c
+++ b/xen/arch/x86/acpi/power.c
@@ -152,9 +152,9 @@ static void acpi_sleep_prepare(u32 state)
return;
if ( acpi_sinfo.vector_width == 32 )
- *(uint32_t *)wakeup_vector_va = bootsym_phys(wakeup_start);
+ *(uint32_t *)wakeup_vector_va = trampsym_phys(wakeup_start);
else
- *(uint64_t *)wakeup_vector_va = bootsym_phys(wakeup_start);
+ *(uint64_t *)wakeup_vector_va = trampsym_phys(wakeup_start);
}
static void acpi_sleep_post(u32 state) {}
@@ -388,7 +388,7 @@ static void tboot_sleep(u8 sleep_state)
g_tboot_shared->acpi_sinfo.wakeup_vector = acpi_sinfo.wakeup_vector;
g_tboot_shared->acpi_sinfo.vector_width = acpi_sinfo.vector_width;
g_tboot_shared->acpi_sinfo.kernel_s3_resume_vector =
- bootsym_phys(wakeup_start);
+ trampsym_phys(wakeup_start);
switch ( sleep_state )
{
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 6d315020d2..cebad00c13 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -689,16 +689,23 @@ trampoline_setup:
lea __PAGE_HYPERVISOR+sym_esi(l1_identmap),%edi
mov %edi,sym_fs(l2_bootmap)
- /* Apply relocations to bootstrap trampoline. */
- mov sym_fs(trampoline_phys),%edx
- mov $sym_offs(__trampoline_rel_start),%edi
-1:
- mov %fs:(%edi),%eax
- add %edx,%fs:(%edi,%eax)
- add $4,%edi
- cmp $sym_offs(__trampoline_rel_stop),%edi
- jb 1b
+ /* Do not parse command line on EFI platform here. */
+ cmpb $0,sym_fs(efi_platform)
+ jnz 1f
+ /* Bail if there is no command line to parse. */
+ mov sym_fs(multiboot_ptr),%ebx
+ testl $MBI_CMDLINE,MB_flags(%ebx)
+ jz 1f
+
+ lea sym_esi(early_boot_opts),%eax
+ push %eax
+ pushl MB_cmdline(%ebx)
+ call cmdline_parse_early
+
+1:
+ /* Apply relocations to 32-bit trampoline for execution in place. */
+ lea sym_esi(perm_trampoline_start),%edx
mov $sym_offs(__trampoline32_rel_start),%edi
1:
mov %fs:(%edi),%eax
@@ -707,6 +714,21 @@ trampoline_setup:
cmp $sym_offs(__trampoline32_rel_stop),%edi
jb 1b
+ cmp $0,sym_esi(skip_realmode)
+ jz .Ldo_realmode
+
+ /* Go directly to trampoline_protmode_entry at its physical address */
+ lea trampoline_protmode_entry-__XEN_VIRT_START(%esi),%eax
+ pushl $BOOT_CS32
+ push %eax
+
+ /* EBX == 0 indicates we are the BP (Boot Processor). */
+ xor %ebx,%ebx
+ retl
+
+.Ldo_realmode:
+ /* Apply relocations to 16-bit boot code. */
+ mov sym_fs(trampoline_phys),%edx
mov $sym_offs(__bootsym_rel_start),%edi
1:
mov %fs:(%edi),%eax
@@ -736,35 +758,12 @@ trampoline_setup:
cmp $sym_offs(__bootdatasym_rel_stop),%edi
jb 1b
- /* Do not parse command line on EFI platform here. */
- cmpb $0,sym_fs(efi_platform)
- jnz 1f
-
- /* Bail if there is no command line to parse. */
- mov sym_fs(multiboot_ptr),%ebx
- testl $MBI_CMDLINE,MB_flags(%ebx)
- jz 1f
-
- lea sym_esi(early_boot_opts),%eax
- push %eax
- pushl MB_cmdline(%ebx)
- call cmdline_parse_early
-
-1:
/* Switch to low-memory stack which lives at the end of trampoline
region. */
mov sym_fs(trampoline_phys),%edi
lea TRAMPOLINE_SPACE+TRAMPOLINE_STACK_SPACE(%edi),%esp
- cmpb $0, sym_fs(skip_realmode)
- jz 1f
- /* If no-real-mode, jump straight to trampoline_protmode_entry */
- lea trampoline_protmode_entry-boot_trampoline_start(%edi),%eax
- /* EBX == 0 indicates we are the BP (Boot Processor). */
- xor %ebx,%ebx
- jmp 2f
-1:
+
/* Go via 16-bit code in trampoline_boot_cpu_entry */
lea trampoline_boot_cpu_entry-boot_trampoline_start(%edi),%eax
-2:
pushl $BOOT_CS32
push %eax
@@ -787,8 +786,6 @@ cmdline_parse_early:
reloc:
#include "reloc.S"
-ENTRY(boot_trampoline_start)
#include "trampoline.S"
-ENTRY(boot_trampoline_end)
#include "x86_64.S"
diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S
index c747d70404..b846977ad0 100644
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -60,7 +60,7 @@ GLOBAL(bootdata_start)
.popsection
#undef trampsym
-#define trampsym(s) ((s)-boot_trampoline_start)
+#define trampsym(s) ((s)-perm_trampoline_start)
#define trampsym_rel(sym, off, opnd...) \
trampsym(sym),##opnd; \
@@ -70,7 +70,7 @@ GLOBAL(bootdata_start)
.popsection
#undef tramp32sym
-#define tramp32sym(s) ((s)-boot_trampoline_start)
+#define tramp32sym(s) ((s)-perm_trampoline_start)
#define tramp32sym_rel(sym, off, opnd...) \
tramp32sym(sym),##opnd; \
@@ -83,6 +83,8 @@ GLOBAL(bootdata_start)
.code16
+ENTRY(perm_trampoline_start)
+
/*
* do_boot_cpu() programs the Startup-IPI to point here. Due to the SIPI
* format, the relocated entrypoint must be 4k aligned.
@@ -90,6 +92,7 @@ GLOBAL(bootdata_start)
* It is entered in Real Mode, with %cs = trampoline_realmode_entry >> 4 and
* %ip = 0.
*/
+
GLOBAL(trampoline_realmode_entry)
mov %cs,%ax
mov %ax,%ds
@@ -97,7 +100,7 @@ GLOBAL(trampoline_realmode_entry)
cld
cli
lidt trampsym(idt_48)
- lgdt trampsym(gdt_48)
+ lgdtl trampsym(gdt_48)
mov $1,%bl # EBX != 0 indicates we are an AP
xor %ax, %ax
inc %ax
@@ -236,11 +239,23 @@ gdt_48: .word 7*8-1
/* The first page of trampoline is permanent, the rest boot-time only. */
/* Reuse the boot trampoline on the 1st trampoline page as stack for wakeup. */
- .equ wakeup_stack, boot_trampoline_start + PAGE_SIZE
+ .equ wakeup_stack, perm_trampoline_start + PAGE_SIZE
.global wakeup_stack
+ENTRY(perm_trampoline_end)
+
/* From here on early boot only. */
+ENTRY(boot_trampoline_start)
+
+ .word 0
+boot16_idt:
+ .word 0, 0, 0 # base = limit = 0
+ .word 0
+boot16_gdt:
+ .word 7*8-1
+ .long tramp32sym_rel(trampoline_gdt,4)
+
.code32
trampoline_boot_cpu_entry:
/* Load pseudo-real-mode segments. */
@@ -304,8 +319,8 @@ trampoline_boot_cpu_entry:
cli
/* Reset GDT and IDT. Some BIOSes clobber GDTR. */
- lidt bootsym(idt_48)
- lgdt bootsym(gdt_48)
+ lidt bootsym(boot16_idt)
+ lgdtl bootsym(boot16_gdt)
/* Enter protected mode, and flush insn queue. */
xor %ax,%ax
@@ -343,7 +358,8 @@ trampoline_boot_cpu_entry:
xor %ebx,%ebx
/* Jump to the common bootstrap entry point. */
- jmp trampoline_protmode_entry
+ mov $tramp32sym_rel(trampoline_protmode_entry,4,%eax)
+ jmp *%eax
#include "video.h"
@@ -379,6 +395,8 @@ rm_idt: .word 256*4-1, 0, 0
#include "video.S"
#endif
+ENTRY(boot_trampoline_end)
+
.pushsection .data.boot16, "aw", @progbits
GLOBAL(bootdata_end)
.popsection
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index a074176c00..05ced26597 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -389,7 +389,7 @@ static void generic_identify(struct cpuinfo_x86 *c)
&c->x86_capability[cpufeat_word(X86_FEATURE_LAHF_LM)],
&c->x86_capability[cpufeat_word(X86_FEATURE_SYSCALL)]);
if (c == &boot_cpu_data)
- bootsym(cpuid_ext_features) =
+ trampsym(cpuid_ext_features) =
c->x86_capability[cpufeat_word(X86_FEATURE_NX)];
if (c->extended_cpuid_level >= 0x80000004)
diff --git a/xen/arch/x86/cpu/intel.c b/xen/arch/x86/cpu/intel.c
index 5356a6ae10..1970eb1848 100644
--- a/xen/arch/x86/cpu/intel.c
+++ b/xen/arch/x86/cpu/intel.c
@@ -269,7 +269,7 @@ static void early_init_intel(struct cpuinfo_x86 *c)
MSR_IA32_MISC_ENABLE_XD_DISABLE);
if (disable) {
wrmsrl(MSR_IA32_MISC_ENABLE, misc_enable & ~disable);
- bootsym(trampoline_misc_enable_off) |= disable;
+ trampsym(trampoline_misc_enable_off) |= disable;
}
if (disable & MSR_IA32_MISC_ENABLE_LIMIT_CPUID)
diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index fac2b5e12a..f8c6ea100c 100644
--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -98,29 +98,6 @@ static void __init efi_arch_relocate_image(unsigned long
delta)
}
}
-extern const s32 __trampoline_rel_start[], __trampoline_rel_stop[];
-extern const s32 __trampoline32_rel_start[], __trampoline32_rel_stop[];
-
-static void __init relocate_trampoline(unsigned long phys)
-{
- const s32 *trampoline_ptr;
-
- trampoline_phys = phys;
-
- if ( !efi_enabled(EFI_LOADER) )
- return;
-
- /* Apply relocations to trampoline. */
- for ( trampoline_ptr = __trampoline_rel_start;
- trampoline_ptr < __trampoline_rel_stop;
- ++trampoline_ptr )
- *(u32 *)(*trampoline_ptr + (long)trampoline_ptr) += phys;
- for ( trampoline_ptr = __trampoline32_rel_start;
- trampoline_ptr < __trampoline32_rel_stop;
- ++trampoline_ptr )
- *(u32 *)(*trampoline_ptr + (long)trampoline_ptr) += phys;
-}
-
static void __init place_string(u32 *addr, const char *s)
{
char *alloc = NULL;
@@ -223,7 +200,7 @@ static void __init efi_arch_pre_exit_boot(void)
{
if ( !cfg.addr )
blexit(L"No memory for trampoline");
- relocate_trampoline(cfg.addr);
+ trampoline_phys = cfg.addr;
}
}
@@ -232,7 +209,6 @@ static void __init noreturn efi_arch_post_exit_boot(void)
u64 cr4 = XEN_MINIMAL_CR4 & ~X86_CR4_PGE, efer;
efi_arch_relocate_image(__XEN_VIRT_START - xen_phys_start);
- memcpy((void *)trampoline_phys, boot_trampoline_start, cfg.size);
/* Set system registers and transfer control. */
asm volatile("pushq $0\n\tpopfq");
@@ -566,14 +542,14 @@ static void __init efi_arch_memory_setup(void)
cfg.addr = 0x100000;
if ( efi_enabled(EFI_LOADER) )
- cfg.size = boot_trampoline_end - boot_trampoline_start;
+ cfg.size = perm_trampoline_end - perm_trampoline_start;
else
cfg.size = TRAMPOLINE_SPACE + TRAMPOLINE_STACK_SPACE;
status = efi_bs->AllocatePages(AllocateMaxAddress, EfiLoaderData,
PFN_UP(cfg.size), &cfg.addr);
if ( status == EFI_SUCCESS )
- relocate_trampoline(cfg.addr);
+ trampoline_phys = cfg.addr;
else
{
cfg.addr = 0;
@@ -665,7 +641,6 @@ static void __init
efi_arch_load_addr_check(EFI_LOADED_IMAGE *loaded_image)
blexit(L"Xen must be loaded below 4Gb.");
if ( xen_phys_start & ((1 << L2_PAGETABLE_SHIFT) - 1) )
blexit(L"Xen must be loaded at a 2Mb boundary.");
- trampoline_xen_phys_start = xen_phys_start;
}
static bool __init efi_arch_use_config_file(EFI_SYSTEM_TABLE *SystemTable)
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 5c818caed2..4faafc180c 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -679,6 +679,45 @@ static unsigned int __init copy_bios_e820(struct e820entry
*map, unsigned int li
return n;
}
+extern const s32 __trampoline_rel_start[], __trampoline_rel_stop[];
+extern const s32 __trampoline32_rel_start[], __trampoline32_rel_stop[];
+
+static void __init relocate_trampoline(unsigned long phys)
+{
+ const s32 *trampoline_ptr;
+ uint32_t tramp32_delta;
+
+ /* Apply relocations to trampoline. */
+ for ( trampoline_ptr = __trampoline_rel_start;
+ trampoline_ptr < __trampoline_rel_stop;
+ ++trampoline_ptr )
+ *(u32 *)(*trampoline_ptr + (long)trampoline_ptr) += phys;
+
+ tramp32_delta = phys;
+ if ( !efi_enabled(EFI_LOADER) )
+ {
+ /*
+ * The non-EFI boot code uses the 32-bit trampoline in place
+ * so will have relocated it to the physical address of
+ * perm_trampoline_start already. Undo that as it needs to
+ * run from low memory for AP startup, because the Xen
+ * physical address range won't be mapped.
+ */
+ tramp32_delta -= trampoline_xen_phys_start;
+ tramp32_delta -= (unsigned long)(perm_trampoline_start -
__XEN_VIRT_START);
+ }
+ for ( trampoline_ptr = __trampoline32_rel_start;
+ trampoline_ptr < __trampoline32_rel_stop;
+ ++trampoline_ptr )
+ {
+ *(u32 *)(*trampoline_ptr + (long)trampoline_ptr) += tramp32_delta;
+ }
+ trampoline_xen_phys_start = xen_phys_start;
+
+ memcpy(trampsym(perm_trampoline_start), perm_trampoline_start,
+ perm_trampoline_end - perm_trampoline_start);
+}
+
void __init noreturn __start_xen(unsigned long mbi_p)
{
char *memmap_type = NULL;
@@ -1073,7 +1112,6 @@ void __init noreturn __start_xen(unsigned long mbi_p)
/* Select relocation address. */
e = end - reloc_size;
xen_phys_start = e;
- bootsym(trampoline_xen_phys_start) = e;
/*
* No PTEs pointing above this address are candidates for
relocation.
@@ -1506,6 +1544,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
else
end_boot_allocator();
+ relocate_trampoline(trampoline_phys);
+
system_state = SYS_STATE_boot;
/*
* No calls involving ACPI code should go between the setting of
@@ -1876,8 +1916,8 @@ int __hwdom_init xen_in_range(unsigned long mfn)
if ( !xen_regions[0].s )
{
/* S3 resume code (and other real mode trampoline code) */
- xen_regions[region_s3].s = bootsym_phys(boot_trampoline_start);
- xen_regions[region_s3].e = bootsym_phys(boot_trampoline_end);
+ xen_regions[region_s3].s = trampsym_phys(perm_trampoline_start);
+ xen_regions[region_s3].e = trampsym_phys(perm_trampoline_end);
/*
* This needs to remain in sync with the uses of the same symbols in
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 5c4254ac87..8e0c844e37 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -47,7 +47,7 @@
#include <asm/tboot.h>
#include <mach_apic.h>
-#define setup_trampoline() (bootsym_phys(trampoline_realmode_entry))
+#define setup_trampoline() (trampsym_phys(trampoline_realmode_entry))
unsigned long __read_mostly trampoline_phys;
@@ -598,7 +598,7 @@ static int do_boot_cpu(int apicid, int cpu)
{
boot_error = 1;
smp_mb();
- if ( bootsym(trampoline_cpu_started) == 0xA5 )
+ if ( trampsym(trampoline_cpu_started) == 0xA5 )
/* trampoline started but...? */
printk("Stuck ??\n");
else
@@ -614,7 +614,7 @@ static int do_boot_cpu(int apicid, int cpu)
}
/* mark "stuck" area as not stuck */
- bootsym(trampoline_cpu_started) = 0;
+ trampsym(trampoline_cpu_started) = 0;
smp_mb();
return rc;
diff --git a/xen/arch/x86/tboot.c b/xen/arch/x86/tboot.c
index 2769e1ccd9..ad2591578d 100644
--- a/xen/arch/x86/tboot.c
+++ b/xen/arch/x86/tboot.c
@@ -369,9 +369,9 @@ void tboot_shutdown(uint32_t shutdown_type)
*/
g_tboot_shared->num_mac_regions = 3;
/* S3 resume code (and other real mode trampoline code) */
- g_tboot_shared->mac_regions[0].start =
bootsym_phys(boot_trampoline_start);
- g_tboot_shared->mac_regions[0].size =
bootsym_phys(boot_trampoline_end) -
-
bootsym_phys(boot_trampoline_start);
+ g_tboot_shared->mac_regions[0].start =
trampsym_phys(perm_trampoline_start);
+ g_tboot_shared->mac_regions[0].size =
trampsym_phys(perm_trampoline_end) -
+
trampsym_phys(perm_trampoline_start);
/* hypervisor .text + .rodata */
g_tboot_shared->mac_regions[1].start = (uint64_t)__pa(&_stext);
g_tboot_shared->mac_regions[1].size = __pa(&__2M_rodata_end) -
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 149cc4f7b5..05d476c423 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -697,7 +697,7 @@ void __init zap_low_mappings(void)
/* Replace with mapping of the boot trampoline only. */
map_pages_to_xen(trampoline_phys, maddr_to_mfn(trampoline_phys),
- PFN_UP(boot_trampoline_end - boot_trampoline_start),
+ PFN_UP(perm_trampoline_end - perm_trampoline_start),
__PAGE_HYPERVISOR);
}
diff --git a/xen/include/asm-x86/acpi.h b/xen/include/asm-x86/acpi.h
index 7032f3a001..8c5381aa47 100644
--- a/xen/include/asm-x86/acpi.h
+++ b/xen/include/asm-x86/acpi.h
@@ -106,7 +106,7 @@ extern int acpi_scan_nodes(u64 start, u64 end);
#define NR_NODE_MEMBLKS (MAX_NUMNODES*2)
extern struct acpi_sleep_info acpi_sinfo;
-#define acpi_video_flags bootsym(video_flags)
+#define acpi_video_flags trampsym(video_flags)
struct xenpf_enter_acpi_sleep;
extern int acpi_enter_sleep(struct xenpf_enter_acpi_sleep *sleep);
extern int acpi_enter_state(u32 state);
diff --git a/xen/include/asm-x86/config.h b/xen/include/asm-x86/config.h
index 50481748f6..e5043fafbd 100644
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -89,12 +89,12 @@
#ifndef __ASSEMBLY__
extern unsigned long trampoline_phys;
-#define bootsym_phys(sym) \
- (((unsigned long)&(sym)-(unsigned
long)&boot_trampoline_start)+trampoline_phys)
-#define bootsym(sym) \
- (*RELOC_HIDE((typeof(&(sym)))__va(__pa(&(sym))), \
- trampoline_phys-__pa(boot_trampoline_start)))
-extern char boot_trampoline_start[], boot_trampoline_end[];
+#define trampsym_phys(sym) \
+ (((unsigned long)&(sym) - (unsigned long)&perm_trampoline_start) +
trampoline_phys)
+#define trampsym(sym) \
+ (*RELOC_HIDE((typeof(&(sym)))__va(__pa(&(sym))), \
+ trampoline_phys - __pa(perm_trampoline_start)))
+extern char perm_trampoline_start[], perm_trampoline_end[];
extern char trampoline_realmode_entry[];
extern unsigned int trampoline_xen_phys_start;
extern unsigned char trampoline_cpu_started;
--
2.21.0
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