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

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Pull x86 asm updates from Ingo Molnar:
 "Two changes:

   - Remove (some) remnants of the vDSO's fake section table mechanism
     that were left behind when the vDSO build process reverted to using
     "objdump -S" to strip the userspace image.

   - Remove hardcoded POPCNT mnemonics now that the minimum binutils
     version supports the symbolic form"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso: Remove a stale/misleading comment from the linker script
  x86/vdso: Remove obsolete "fake section table" reservation
  x86: Use POPCNT mnemonics in arch_hweight.h
This commit is contained in:
Linus Torvalds 2018-12-26 16:25:06 -08:00
commit 38fabca18f
3 changed files with 2 additions and 43 deletions
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27
arch/x86/entry/vdso/vdso-layout.lds.S
View File

@ -7,16 +7,6 @@
* This script controls its layout.
*/
#if defined(BUILD_VDSO64)
# define SHDR_SIZE 64
#elif defined(BUILD_VDSO32) || defined(BUILD_VDSOX32)
# define SHDR_SIZE 40
#else
# error unknown VDSO target
#endif
#define NUM_FAKE_SHDRS 13
SECTIONS
{
/*
@ -60,20 +50,8 @@ SECTIONS
*(.bss*)
*(.dynbss*)
*(.gnu.linkonce.b.*)
/*
* Ideally this would live in a C file, but that won't
* work cleanly for x32 until we start building the x32
* C code using an x32 toolchain.
*/
VDSO_FAKE_SECTION_TABLE_START = .;
. = . + NUM_FAKE_SHDRS * SHDR_SIZE;
VDSO_FAKE_SECTION_TABLE_END = .;
} :text
.fake_shstrtab : { *(.fake_shstrtab) } :text
.note : { *(.note.*) } :text :note
.eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
@ -87,11 +65,6 @@ SECTIONS
.text : { *(.text*) } :text =0x90909090,
/*
* At the end so that eu-elflint stays happy when vdso2c strips
* these. A better implementation would avoid allocating space
* for these.
*/
.altinstructions : { *(.altinstructions) } :text
.altinstr_replacement : { *(.altinstr_replacement) } :text

8
arch/x86/entry/vdso/vdso2c.c
View File

@ -76,8 +76,6 @@ enum {
sym_hpet_page,
sym_pvclock_page,
sym_hvclock_page,
sym_VDSO_FAKE_SECTION_TABLE_START,
sym_VDSO_FAKE_SECTION_TABLE_END,
};
const int special_pages[] = {
@ -98,12 +96,6 @@ struct vdso_sym required_syms[] = {
[sym_hpet_page] = {"hpet_page", true},
[sym_pvclock_page] = {"pvclock_page", true},
[sym_hvclock_page] = {"hvclock_page", true},
[sym_VDSO_FAKE_SECTION_TABLE_START] = {
"VDSO_FAKE_SECTION_TABLE_START", false
},
[sym_VDSO_FAKE_SECTION_TABLE_END] = {
"VDSO_FAKE_SECTION_TABLE_END", false
},
{"VDSO32_NOTE_MASK", true},
{"__kernel_vsyscall", true},
{"__kernel_sigreturn", true},

10
arch/x86/include/asm/arch_hweight.h
View File

@ -5,15 +5,9 @@
#include <asm/cpufeatures.h>
#ifdef CONFIG_64BIT
/* popcnt %edi, %eax */
#define POPCNT32 ".byte 0xf3,0x0f,0xb8,0xc7"
/* popcnt %rdi, %rax */
#define POPCNT64 ".byte 0xf3,0x48,0x0f,0xb8,0xc7"
#define REG_IN "D"
#define REG_OUT "a"
#else
/* popcnt %eax, %eax */
#define POPCNT32 ".byte 0xf3,0x0f,0xb8,0xc0"
#define REG_IN "a"
#define REG_OUT "a"
#endif
@ -24,7 +18,7 @@ static __always_inline unsigned int __arch_hweight32(unsigned int w)
{
unsigned int res;
asm (ALTERNATIVE("call __sw_hweight32", POPCNT32, X86_FEATURE_POPCNT)
asm (ALTERNATIVE("call __sw_hweight32", "popcntl %1, %0", X86_FEATURE_POPCNT)
: "="REG_OUT (res)
: REG_IN (w));
@ -52,7 +46,7 @@ static __always_inline unsigned long __arch_hweight64(__u64 w)
{
unsigned long res;
asm (ALTERNATIVE("call __sw_hweight64", POPCNT64, X86_FEATURE_POPCNT)
asm (ALTERNATIVE("call __sw_hweight64", "popcntq %1, %0", X86_FEATURE_POPCNT)
: "="REG_OUT (res)
: REG_IN (w));