Merge branch 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 build bits from Peter Anvin:
 "Various build-related minor bits.

  Most of this is work by David Woodhouse to be able to compile the
  early boot code with clang/llvm; we have also managed to push an
  actual -m16 option into gcc 4.9 so this makes us use that option if
  available instead of hacking it.

  The balance is a patch from Michael Davidson to the relocs program to
  help manual debugging.

  None of these should change the actual compiled binary with currently
  released compilers"

* 'x86-build-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, build: Build 16-bit code with -m16 where possible
  x86, boot: Fix word-size assumptions in has_eflag() inline asm
  x86, boot: Use __attribute__((used)) to ensure videocard structs are emitted
  x86: Remove duplication of 16-bit CFLAGS
  x86, relocs: Add manual debug mode
This commit is contained in:
Linus Torvalds 2014-01-30 18:13:20 -08:00
commit 10ffe3dbf7
8 changed files with 91 additions and 43 deletions

View File

@ -11,6 +11,28 @@ else
KBUILD_DEFCONFIG := $(ARCH)_defconfig
endif
# How to compile the 16-bit code. Note we always compile for -march=i386;
# that way we can complain to the user if the CPU is insufficient.
#
# The -m16 option is supported by GCC >= 4.9 and clang >= 3.5. For
# older versions of GCC, we need to play evil and unreliable tricks to
# attempt to ensure that our asm(".code16gcc") is first in the asm
# output.
CODE16GCC_CFLAGS := -m32 -include $(srctree)/arch/x86/boot/code16gcc.h \
$(call cc-option, -fno-toplevel-reorder,\
$(call cc-option, -fno-unit-at-a-time))
M16_CFLAGS := $(call cc-option, -m16, $(CODE16GCC_CFLAGS))
REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os -D__KERNEL__ \
-DDISABLE_BRANCH_PROFILING \
-Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
-mno-mmx -mno-sse \
$(call cc-option, -ffreestanding) \
$(call cc-option, -fno-stack-protector) \
$(call cc-option, -mpreferred-stack-boundary=2)
export REALMODE_CFLAGS
# BITS is used as extension for files which are available in a 32 bit
# and a 64 bit version to simplify shared Makefiles.
# e.g.: obj-y += foo_$(BITS).o

View File

@ -51,20 +51,7 @@ $(obj)/cpustr.h: $(obj)/mkcpustr FORCE
# ---------------------------------------------------------------------------
# How to compile the 16-bit code. Note we always compile for -march=i386,
# that way we can complain to the user if the CPU is insufficient.
KBUILD_CFLAGS := $(USERINCLUDE) -m32 -g -Os -D_SETUP -D__KERNEL__ \
-DDISABLE_BRANCH_PROFILING \
-Wall -Wstrict-prototypes \
-march=i386 -mregparm=3 \
-include $(srctree)/$(src)/code16gcc.h \
-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
-mno-mmx -mno-sse \
$(call cc-option, -ffreestanding) \
$(call cc-option, -fno-toplevel-reorder,\
$(call cc-option, -fno-unit-at-a-time)) \
$(call cc-option, -fno-stack-protector) \
$(call cc-option, -mpreferred-stack-boundary=2)
KBUILD_CFLAGS := $(USERINCLUDE) $(REALMODE_CFLAGS) -D_SETUP
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n

View File

@ -28,20 +28,35 @@ static int has_fpu(void)
return fsw == 0 && (fcw & 0x103f) == 0x003f;
}
/*
* For building the 16-bit code we want to explicitly specify 32-bit
* push/pop operations, rather than just saying 'pushf' or 'popf' and
* letting the compiler choose. But this is also included from the
* compressed/ directory where it may be 64-bit code, and thus needs
* to be 'pushfq' or 'popfq' in that case.
*/
#ifdef __x86_64__
#define PUSHF "pushfq"
#define POPF "popfq"
#else
#define PUSHF "pushfl"
#define POPF "popfl"
#endif
int has_eflag(unsigned long mask)
{
unsigned long f0, f1;
asm volatile("pushf \n\t"
"pushf \n\t"
asm volatile(PUSHF " \n\t"
PUSHF " \n\t"
"pop %0 \n\t"
"mov %0,%1 \n\t"
"xor %2,%1 \n\t"
"push %1 \n\t"
"popf \n\t"
"pushf \n\t"
POPF " \n\t"
PUSHF " \n\t"
"pop %1 \n\t"
"popf"
POPF
: "=&r" (f0), "=&r" (f1)
: "ri" (mask));

View File

@ -80,7 +80,7 @@ struct card_info {
u16 xmode_n; /* Size of unprobed mode range */
};
#define __videocard struct card_info __attribute__((section(".videocards")))
#define __videocard struct card_info __attribute__((used,section(".videocards")))
extern struct card_info video_cards[], video_cards_end[];
int mode_defined(u16 mode); /* video.c */

View File

@ -64,20 +64,7 @@ $(obj)/realmode.relocs: $(obj)/realmode.elf FORCE
# ---------------------------------------------------------------------------
# How to compile the 16-bit code. Note we always compile for -march=i386,
# that way we can complain to the user if the CPU is insufficient.
KBUILD_CFLAGS := $(LINUXINCLUDE) -m32 -g -Os -D_SETUP -D__KERNEL__ -D_WAKEUP \
-I$(srctree)/arch/x86/boot \
-DDISABLE_BRANCH_PROFILING \
-Wall -Wstrict-prototypes \
-march=i386 -mregparm=3 \
-include $(srctree)/$(src)/../../boot/code16gcc.h \
-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
-mno-mmx -mno-sse \
$(call cc-option, -ffreestanding) \
$(call cc-option, -fno-toplevel-reorder,\
$(call cc-option, -fno-unit-at-a-time)) \
$(call cc-option, -fno-stack-protector) \
$(call cc-option, -mpreferred-stack-boundary=2)
KBUILD_CFLAGS := $(LINUXINCLUDE) $(REALMODE_CFLAGS) -D_SETUP -D_WAKEUP \
-I$(srctree)/arch/x86/boot
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n

View File

@ -1025,6 +1025,29 @@ static void emit_relocs(int as_text, int use_real_mode)
}
}
/*
* As an aid to debugging problems with different linkers
* print summary information about the relocs.
* Since different linkers tend to emit the sections in
* different orders we use the section names in the output.
*/
static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
const char *symname)
{
printf("%s\t%s\t%s\t%s\n",
sec_name(sec->shdr.sh_info),
rel_type(ELF_R_TYPE(rel->r_info)),
symname,
sec_name(sym->st_shndx));
return 0;
}
static void print_reloc_info(void)
{
printf("reloc section\treloc type\tsymbol\tsymbol section\n");
walk_relocs(do_reloc_info);
}
#if ELF_BITS == 64
# define process process_64
#else
@ -1032,7 +1055,8 @@ static void emit_relocs(int as_text, int use_real_mode)
#endif
void process(FILE *fp, int use_real_mode, int as_text,
int show_absolute_syms, int show_absolute_relocs)
int show_absolute_syms, int show_absolute_relocs,
int show_reloc_info)
{
regex_init(use_real_mode);
read_ehdr(fp);
@ -1050,5 +1074,9 @@ void process(FILE *fp, int use_real_mode, int as_text,
print_absolute_relocs();
return;
}
if (show_reloc_info) {
print_reloc_info();
return;
}
emit_relocs(as_text, use_real_mode);
}

View File

@ -29,8 +29,9 @@ enum symtype {
};
void process_32(FILE *fp, int use_real_mode, int as_text,
int show_absolute_syms, int show_absolute_relocs);
int show_absolute_syms, int show_absolute_relocs,
int show_reloc_info);
void process_64(FILE *fp, int use_real_mode, int as_text,
int show_absolute_syms, int show_absolute_relocs);
int show_absolute_syms, int show_absolute_relocs,
int show_reloc_info);
#endif /* RELOCS_H */

View File

@ -11,12 +11,13 @@ void die(char *fmt, ...)
static void usage(void)
{
die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode]" \
" vmlinux\n");
}
int main(int argc, char **argv)
{
int show_absolute_syms, show_absolute_relocs;
int show_absolute_syms, show_absolute_relocs, show_reloc_info;
int as_text, use_real_mode;
const char *fname;
FILE *fp;
@ -25,6 +26,7 @@ int main(int argc, char **argv)
show_absolute_syms = 0;
show_absolute_relocs = 0;
show_reloc_info = 0;
as_text = 0;
use_real_mode = 0;
fname = NULL;
@ -39,6 +41,10 @@ int main(int argc, char **argv)
show_absolute_relocs = 1;
continue;
}
if (strcmp(arg, "--reloc-info") == 0) {
show_reloc_info = 1;
continue;
}
if (strcmp(arg, "--text") == 0) {
as_text = 1;
continue;
@ -67,10 +73,12 @@ int main(int argc, char **argv)
rewind(fp);
if (e_ident[EI_CLASS] == ELFCLASS64)
process_64(fp, use_real_mode, as_text,
show_absolute_syms, show_absolute_relocs);
show_absolute_syms, show_absolute_relocs,
show_reloc_info);
else
process_32(fp, use_real_mode, as_text,
show_absolute_syms, show_absolute_relocs);
show_absolute_syms, show_absolute_relocs,
show_reloc_info);
fclose(fp);
return 0;
}