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

torvalds · torvalds · commit 38fabca18fc4 · 2018-12-26T16:25:06.000-08:00
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
diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S
@@ -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
 
diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c
@@ -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},
diff --git a/arch/x86/include/asm/arch_hweight.h b/arch/x86/include/asm/arch_hweight.h
@@ -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));
 
