Re: [PATCH 1/1] intel_txt: to fix build errors of CONFIG_ACPI_SLEEP

[H. Peter Anvin]

On 08/12/2009 11:46 PM, Ingo Molnar wrote:
> * Wang, Shane <shane.wang@xxxxxxxxx> wrote:
> 
>> Signed-off-by: Shane Wang <shane.wang@xxxxxxxxx>
>>
>> diff -r 7358cf1b3090 arch/x86/kernel/tboot.c
>> --- a/arch/x86/kernel/tboot.c   Wed Aug 12 03:04:23 2009 -0700
>> +++ b/arch/x86/kernel/tboot.c   Wed Aug 12 18:06:21 2009 -0700
>> @@ -169,6 +169,7 @@ void tboot_create_trampoline(void)
>>
>>  static void set_mac_regions(void)
>>  {
>> +#ifdef CONFIG_ACPI_SLEEP
>>         tboot->num_mac_regions = 3;
>>         /* S3 resume code */
>>         tboot->mac_regions[0].start = PFN_PHYS(PFN_DOWN(acpi_wakeup_address));
>> @@ -181,6 +182,7 @@ static void set_mac_regions(void)
>>         tboot->mac_regions[2].start = PFN_PHYS(PFN_DOWN(virt_to_phys(&_text)));
>>         tboot->mac_regions[2].size = PFN_PHYS(PFN_UP(virt_to_phys(&_end))) -
>>                                      PFN_PHYS(PFN_DOWN(virt_to_phys(&_text)));
>> +#endif
> 
> These #ifdefs are quite ugly. Why not add a 'depends on ACPI_SLEEP' 
> rule to the INTEL_TXT Kconfig section?

I *strongly* disagree with that kind of false dependencies.  It makes it
seem like there is something magic going on, which invites cargo cult
programming in the future.  I also think those particular #ifdefs are
fairly innocuous... it's not like they're hiding flow of control or
major chunks of code.

However, I think the actual code to set the sections is ugly as hell,
which is probably why the #ifdef sticks in your eyes.

Consider the attached instead patch, which abstracts some of the (way
more complex than it should be) open-coded stuff and therefore makes it
stick out less.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index 1ab8012..af16d26 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -34,6 +34,7 @@
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/fixmap.h>
+#include <asm/proto.h>
 #include <asm/setup.h>
 #include <asm/tboot.h>
 #include <asm/e820.h>
@@ -164,23 +165,36 @@ void tboot_create_trampoline(void)
 	map_base = PFN_DOWN(tboot->tboot_base);
 	map_size = PFN_UP(tboot->tboot_size);
 	if (map_tboot_pages(map_base << PAGE_SHIFT, map_base, map_size))
-		panic("tboot: Error mapping tboot pages (mfns) @ 0x%x, 0x%x\n", map_base, map_size);
+		panic("tboot: Error mapping tboot pages (mfns) @ 0x%x, 0x%x\n",
+		      map_base, map_size);
+}
+
+static void add_mac_region(phys_addr_t start, unsigned long size)
+{
+	struct tboot_mac_region *mr;
+	phys_addr_t end = start + size;
+
+	if (start && size) {
+		mr = &tboot->mac_regions[tboot->num_mac_regions++];
+		mr->start = round_down(start, PAGE_SIZE);
+		mr->size  = round_up(end, PAGE_SIZE) - mr->start;
+	}
 }
 
 static void set_mac_regions(void)
 {
-	tboot->num_mac_regions = 3;
+	tboot->num_mac_regions = 0;
+
+#ifdef CONFIG_ACPI_SLEEP
 	/* S3 resume code */
-	tboot->mac_regions[0].start = PFN_PHYS(PFN_DOWN(acpi_wakeup_address));
-	tboot->mac_regions[0].size = PFN_UP(WAKEUP_SIZE) << PAGE_SHIFT;
+	add_mac_region(acpi_wakeup_address, WAKEUP_SIZE);
+#endif
+#ifdef CONFIG_X86_TRAMPOLINE
 	/* AP trampoline code */
-	tboot->mac_regions[1].start =
-			PFN_PHYS(PFN_DOWN(virt_to_phys(trampoline_base)));
-	tboot->mac_regions[1].size = PFN_UP(TRAMPOLINE_SIZE) << PAGE_SHIFT;
+	add_mac_region(virt_to_phys(trampoline_base), TRAMPOLINE_SIZE);
+#endif
 	/* kernel code + data + bss */
-	tboot->mac_regions[2].start = PFN_PHYS(PFN_DOWN(virt_to_phys(&_text)));
-	tboot->mac_regions[2].size = PFN_PHYS(PFN_UP(virt_to_phys(&_end))) -
-				     PFN_PHYS(PFN_DOWN(virt_to_phys(&_text)));
+	add_mac_region(virt_to_phys(_text), _end - _text);
 }
 
 void tboot_shutdown(u32 shutdown_type)
@@ -253,7 +267,9 @@ void tboot_sleep(u8 sleep_state, u32 pm1a_control, u32 pm1b_control)
 	tboot->acpi_sinfo.pm1b_cnt_val = pm1b_control;
 	/* we always use the 32b wakeup vector */
 	tboot->acpi_sinfo.vector_width = 32;
+#ifdef CONFIG_ACPI_SLEEP
 	tboot->acpi_sinfo.kernel_s3_resume_vector = acpi_wakeup_address;
+#endif
 
 	if (sleep_state >= ACPI_S_STATE_COUNT ||
 	    acpi_shutdown_map[sleep_state] == -1) {