Perhaps not the biggest deal, but I do like to get low-hanging fixes out
of the way if they appear.
One very significant item I found. It appears GCC is fine with %rbx being
clobbered when building PIC in 64-bit mode, even though it has problems
with %ebx being clobbered when building PIC in 32-bit mode.
One other item I did notice. Are there really any processors in the amd64
class that *don't* support CPUID? I'd like to hardcode
grub_cpu_is_cpuid_supported() to return 1 if __x86_64__ is defined, but
I'm a tad worried I'll be unpleasantly surprised.
--
(\___(\___(\______ --=> 8-) EHM <=-- ______/)___/)___/)
\BS ( | e...@gremlin.m5p.com PGP F6B23DE0 | ) /
\_CS\ | _____ -O #include <stddisclaimer.h> O- _____ | / _/
2477\___\_|_/DC21 03A0 5D61 985B <-PGP-> F2BE 6526 ABD2 F6B2\_|_/___/3DE0
=== modified file 'ChangeLog'
--- ChangeLog 2011-01-05 00:28:28 +0000
+++ ChangeLog 2011-01-05 05:42:55 +0000
@@ -1,3 +1,13 @@
+2011-01-04 Elliott Mitchell <ehem+g...@m5p.com>
+
+ * include/grub/i386/tsc.h: Create shared macros for handling all the
+ tiny little blobs of assembly where we'd like to be able to clobber
+ %ebx. Replace the many uses of #ifdef(APPLE_CC)/#ifdef(__x64_64__)
+ with usage of these macros. Testing found %rbx *can* be clobbered in
+ amd64/64-bit mode.
+ * grub-core/loader/i386/xnu.c: Propogate usage of the macros created
+ above to this file. Removes sections of copy&paste code.
+
2011-01-05 Vladimir Serbinenko <phco...@gmail.com>
* util/grub-install.in: Determine ofpathname, nvsetenv and efibootmgr
=== modified file 'grub-core/loader/i386/xnu.c'
--- grub-core/loader/i386/xnu.c 2010-09-05 11:05:36 +0000
+++ grub-core/loader/i386/xnu.c 2011-01-05 01:47:27 +0000
@@ -1,6 +1,6 @@
/*
* GRUB -- GRand Unified Bootloader
- * Copyright (C) 2009 Free Software Foundation, Inc.
+ * Copyright (C) 2009,2011 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -130,62 +130,35 @@
if (! grub_cpu_is_cpuid_supported ())
return sane_value;
-#ifdef APPLE_CC
asm volatile ("movl $0, %%eax\n"
-#ifdef __x86_64__
- "push %%rbx\n"
-#else
- "push %%ebx\n"
-#endif
+ SAVE_REG_B
"cpuid\n"
-#ifdef __x86_64__
- "pop %%rbx\n"
-#else
- "pop %%ebx\n"
+#ifdef REGISTER_B_PRECIOUS
+ "movl %ebx, %edi"
#endif
+ RESTORE_REG_B
: "=a" (max_cpuid),
- "=d" (manufacturer[1]), "=c" (manufacturer[2]));
-
- /* Only Intel for now is done. */
- if (grub_memcmp (manufacturer + 1, "ineIntel", 12) != 0)
- return sane_value;
-
+#ifdef REGISTER_B_PRECIOUS
+ "=di" (manufacturer[0]),
#else
- asm volatile ("movl $0, %%eax\n"
- "cpuid"
- : "=a" (max_cpuid), "=b" (manufacturer[0]),
- "=d" (manufacturer[1]), "=c" (manufacturer[2]));
+ "=b" (manufacturer[0]),
+#endif
+ "=d" (manufacturer[1]), "=c" (manufacturer[2]));
/* Only Intel for now is done. */
if (grub_memcmp (manufacturer, "GenuineIntel", 12) != 0)
return sane_value;
-#endif
/* Check Speedstep. */
if (max_cpuid < 1)
return sane_value;
-#ifdef APPLE_CC
- asm volatile ("movl $1, %%eax\n"
-#ifdef __x86_64__
- "push %%rbx\n"
-#else
- "push %%ebx\n"
-#endif
- "cpuid\n"
-#ifdef __x86_64__
- "pop %%rbx\n"
-#else
- "pop %%ebx\n"
-#endif
- : "=c" (capabilities):
- : "%rax", "%rdx");
-#else
- asm volatile ("movl $1, %%eax\n"
+ asm volatile ("movl $1, %%eax\n"
+ SAVE_REG_B
"cpuid"
+ RESTORE_REG_B
: "=c" (capabilities):
- : "%rax", "%rbx", "%rdx");
-#endif
+ : "%rax" CLOBBER_REG_B, "%rdx");
if (! (capabilities & (1 << 7)))
return sane_value;
=== modified file 'include/grub/i386/tsc.h'
--- include/grub/i386/tsc.h 2010-01-03 22:05:07 +0000
+++ include/grub/i386/tsc.h 2011-01-05 05:23:07 +0000
@@ -1,6 +1,6 @@
/*
* GRUB -- GRand Unified Bootloader
- * Copyright (C) 2008,2009 Free Software Foundation, Inc.
+ * Copyright (C) 2008,2009,2011 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@@ -21,6 +21,21 @@
#include <grub/types.h>
+/* for use with assembly segments utilizing the B register, alas in PIC
+* non-64-bit mode, GCC can't deal with it being clobbered. */
+#if (defined(APPLE_CC) || defined(__pic__)) && !defined(__x86_64__)
+#define REGISTER_C_PRECIOUS 1
+#define SAVE_REG_B "push %ebx\n"
+#define RESTORE_REG_B "pop %ebx\n"
+#define CLOBBER_REG_B
+
+#else
+#define SAVE_REG_B
+#define RESTORE_REG_B
+#define CLOBBER_REG_B "%rbx".
+#endif
+
+
/* Read the TSC value, which increments with each CPU clock cycle. */
static __inline grub_uint64_t
grub_get_tsc (void)
@@ -29,24 +44,11 @@
/* The CPUID instruction is a 'serializing' instruction, and
avoids out-of-order execution of the RDTSC instruction. */
-#ifdef APPLE_CC
__asm__ __volatile__ ("xorl %%eax, %%eax\n\t"
-#ifdef __x86_64__
- "push %%rbx\n"
-#else
- "push %%ebx\n"
-#endif
+ SAVE_REG_B
"cpuid\n"
-#ifdef __x86_64__
- "pop %%rbx\n"
-#else
- "pop %%ebx\n"
-#endif
- :::"%rax", "%rcx", "%rdx");
-#else
- __asm__ __volatile__ ("xorl %%eax, %%eax\n\t"
- "cpuid":::"%rax", "%rbx", "%rcx", "%rdx");
-#endif
+ RESTORE_REG_B
+ :::"%rax", CLOBBER_REG_B "%rcx", "%rdx");
/* Read TSC value. We cannot use "=A", since this would use
%rax on x86_64. */
__asm__ __volatile__ ("rdtsc":"=a" (lo), "=d" (hi));
@@ -54,12 +56,17 @@
return (((grub_uint64_t) hi) << 32) | lo;
}
-#ifdef __x86_64__
static __inline int
grub_cpu_is_cpuid_supported (void)
{
- grub_uint64_t id_supported;
+#ifdef __x86_64__
+ /* there really any processors in this class that *don't* support cpuid?! */
+#if 0
+ return 1;
+#endif
+
+ grub_size_t id_supported;
__asm__ ("pushfq\n\t"
"popq %%rax /* Get EFLAGS into EAX */\n\t"
@@ -75,14 +82,8 @@
: /* Clobbered: */ "%rcx");
return id_supported != 0;
-}
-
#else
-
-static __inline int
-grub_cpu_is_cpuid_supported (void)
-{
- grub_uint32_t id_supported;
+ grub_size_t id_supported;
__asm__ ("pushfl\n\t"
"popl %%eax /* Get EFLAGS into EAX */\n\t"
@@ -98,6 +99,7 @@
: /* Clobbered: */ "%rcx");
return id_supported != 0;
+#endif
}
#endif
@@ -109,29 +111,13 @@
return 0;
grub_uint32_t features;
-#ifdef APPLE_CC
- __asm__ ("movl $1, %%eax\n\t"
-#ifdef __x86_64__
- "push %%rbx\n"
-#else
- "push %%ebx\n"
-#endif
- "cpuid\n"
-#ifdef __x86_64__
- "pop %%rbx\n"
-#else
- "pop %%ebx\n"
-#endif
- : "=d" (features)
- : /* No inputs. */
- : /* Clobbered: */ "%rax", "%rcx");
-#else
- __asm__ ("movl $1, %%eax\n\t"
- "cpuid\n"
- : "=d" (features)
- : /* No inputs. */
- : /* Clobbered: */ "%rax", "%rbx", "%rcx");
-#endif
+ __asm__ ("movl $1, %%eax\n\t"
+ SAVE_REG_B
+ "cpuid\n"
+ RESTORE_REG_B
+ : "=d" (features)
+ : /* No inputs. */
+ : /* Clobbered: */ "%rax", CLOBBER_REG_B "%rcx");
return (features & (1 << 4)) != 0;
}
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