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

Pull x86 asm updates from Ingo Molnar:

 - Add UMIP emulation/spoofing for 64-bit processes as well, because of
   Wine based gaming.

 - Clean up symbols/labels in low level asm code

 - Add an assembly optimized mul_u64_u32_div() implementation on x86-64.

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/umip: Add emulation (spoofing) for UMIP covered instructions in 64-bit processes as well
  x86/asm: Make some functions local labels
  x86/asm/suspend: Get rid of bogus_64_magic
  x86/math64: Provide a sane mul_u64_u32_div() implementation for x86_64
This commit is contained in:
Linus Torvalds 2019-09-16 18:07:08 -07:00
parent 7e67a85999 e86c2c8b93
commit df4c0b18f2
9 changed files with 96 additions and 70 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/boot/compressed/head_32.S
View File

@ -140,7 +140,7 @@ ENTRY(startup_32)
/*
* Jump to the relocated address.
*/
leal relocated(%ebx), %eax
leal .Lrelocated(%ebx), %eax
jmp *%eax
ENDPROC(startup_32)
@ -209,7 +209,7 @@ ENDPROC(efi32_stub_entry)
#endif
.text
relocated:
.Lrelocated:
/*
* Clear BSS (stack is currently empty)

18
arch/x86/boot/compressed/head_64.S
View File

@ -87,7 +87,7 @@ ENTRY(startup_32)
call verify_cpu
testl %eax, %eax
jnz no_longmode
jnz .Lno_longmode
/*
* Compute the delta between where we were compiled to run at
@ -322,7 +322,7 @@ ENTRY(startup_64)
1: popq %rdi
subq $1b, %rdi
call adjust_got
call .Ladjust_got
/*
* At this point we are in long mode with 4-level paging enabled,
@ -421,7 +421,7 @@ trampoline_return:
/* The new adjustment is the relocation address */
movq %rbx, %rdi
call adjust_got
call .Ladjust_got
/*
* Copy the compressed kernel to the end of our buffer
@ -440,7 +440,7 @@ trampoline_return:
/*
* Jump to the relocated address.
*/
leaq relocated(%rbx), %rax
leaq .Lrelocated(%rbx), %rax
jmp *%rax
#ifdef CONFIG_EFI_STUB
@ -511,7 +511,7 @@ ENDPROC(efi64_stub_entry)
#endif
.text
relocated:
.Lrelocated:
/*
* Clear BSS (stack is currently empty)
@ -548,7 +548,7 @@ relocated:
* first time we touch GOT).
* RDI is the new adjustment to apply.
*/
adjust_got:
.Ladjust_got:
/* Walk through the GOT adding the address to the entries */
leaq _got(%rip), %rdx
leaq _egot(%rip), %rcx
@ -622,7 +622,7 @@ ENTRY(trampoline_32bit_src)
movl %eax, %cr4
/* Calculate address of paging_enabled() once we are executing in the trampoline */
leal paging_enabled - trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_OFFSET(%ecx), %eax
leal .Lpaging_enabled - trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_OFFSET(%ecx), %eax
/* Prepare the stack for far return to Long Mode */
pushl $__KERNEL_CS
@ -635,7 +635,7 @@ ENTRY(trampoline_32bit_src)
lret
.code64
paging_enabled:
.Lpaging_enabled:
/* Return from the trampoline */
jmp *%rdi
@ -647,7 +647,7 @@ paging_enabled:
.org trampoline_32bit_src + TRAMPOLINE_32BIT_CODE_SIZE
.code32
no_longmode:
.Lno_longmode:
/* This isn't an x86-64 CPU, so hang intentionally, we cannot continue */
1:
hlt

4
arch/x86/entry/entry_64.S
View File

@ -1058,10 +1058,10 @@ ENTRY(native_load_gs_index)
ENDPROC(native_load_gs_index)
EXPORT_SYMBOL(native_load_gs_index)
_ASM_EXTABLE(.Lgs_change, bad_gs)
_ASM_EXTABLE(.Lgs_change, .Lbad_gs)
.section .fixup, "ax"
/* running with kernelgs */
bad_gs:
.Lbad_gs:
SWAPGS /* switch back to user gs */
.macro ZAP_GS
/* This can't be a string because the preprocessor needs to see it. */

13
arch/x86/include/asm/div64.h
View File

@ -73,6 +73,19 @@ static inline u64 mul_u32_u32(u32 a, u32 b)
#else
# include <asm-generic/div64.h>
static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div)
{
u64 q;
asm ("mulq %2; divq %3" : "=a" (q)
: "a" (a), "rm" ((u64)mul), "rm" ((u64)div)
: "rdx");
return q;
}
#define mul_u64_u32_div mul_u64_u32_div
#endif /* CONFIG_X86_32 */
#endif /* _ASM_X86_DIV64_H */

10
arch/x86/kernel/acpi/wakeup_64.S
View File

@ -18,8 +18,13 @@ ENTRY(wakeup_long64)
movq saved_magic, %rax
movq $0x123456789abcdef0, %rdx
cmpq %rdx, %rax
jne bogus_64_magic
je 2f
/* stop here on a saved_magic mismatch */
movq $0xbad6d61676963, %rcx
1:
jmp 1b
2:
movw $__KERNEL_DS, %ax
movw %ax, %ss
movw %ax, %ds
@ -37,9 +42,6 @@ ENTRY(wakeup_long64)
jmp *%rax
ENDPROC(wakeup_long64)
bogus_64_magic:
jmp bogus_64_magic
ENTRY(do_suspend_lowlevel)
FRAME_BEGIN
subq $8, %rsp

65
arch/x86/kernel/umip.c
View File

@ -19,7 +19,7 @@
/** DOC: Emulation for User-Mode Instruction Prevention (UMIP)
*
* The feature User-Mode Instruction Prevention present in recent Intel
* processor prevents a group of instructions (sgdt, sidt, sldt, smsw, and str)
* processor prevents a group of instructions (SGDT, SIDT, SLDT, SMSW and STR)
* from being executed with CPL > 0. Otherwise, a general protection fault is
* issued.
*
@ -36,8 +36,8 @@
* DOSEMU2) rely on this subset of instructions to function.
*
* The instructions protected by UMIP can be split in two groups. Those which
* return a kernel memory address (sgdt and sidt) and those which return a
* value (sldt, str and smsw).
* return a kernel memory address (SGDT and SIDT) and those which return a
* value (SLDT, STR and SMSW).
*
* For the instructions that return a kernel memory address, applications
* such as WineHQ rely on the result being located in the kernel memory space,
@ -45,15 +45,13 @@
* value that, lies close to the top of the kernel memory. The limit for the GDT
* and the IDT are set to zero.
*
* Given that sldt and str are not commonly used in programs that run on WineHQ
* Given that SLDT and STR are not commonly used in programs that run on WineHQ
* or DOSEMU2, they are not emulated.
*
* The instruction smsw is emulated to return the value that the register CR0
* has at boot time as set in the head_32.
*
* Also, emulation is provided only for 32-bit processes; 64-bit processes
* that attempt to use the instructions that UMIP protects will receive the
* SIGSEGV signal issued as a consequence of the general protection fault.
* Emulation is provided for both 32-bit and 64-bit processes.
*
* Care is taken to appropriately emulate the results when segmentation is
* used. That is, rather than relying on USER_DS and USER_CS, the function
@ -63,17 +61,18 @@
* application uses a local descriptor table.
*/
#define UMIP_DUMMY_GDT_BASE 0xfffe0000
#define UMIP_DUMMY_IDT_BASE 0xffff0000
#define UMIP_DUMMY_GDT_BASE 0xfffffffffffe0000ULL
#define UMIP_DUMMY_IDT_BASE 0xffffffffffff0000ULL
/*
* The SGDT and SIDT instructions store the contents of the global descriptor
* table and interrupt table registers, respectively. The destination is a
* memory operand of X+2 bytes. X bytes are used to store the base address of
* the table and 2 bytes are used to store the limit. In 32-bit processes, the
* only processes for which emulation is provided, X has a value of 4.
* the table and 2 bytes are used to store the limit. In 32-bit processes X
* has a value of 4, in 64-bit processes X has a value of 8.
*/
#define UMIP_GDT_IDT_BASE_SIZE 4
#define UMIP_GDT_IDT_BASE_SIZE_64BIT 8
#define UMIP_GDT_IDT_BASE_SIZE_32BIT 4
#define UMIP_GDT_IDT_LIMIT_SIZE 2
#define UMIP_INST_SGDT 0 /* 0F 01 /0 */
@ -189,6 +188,7 @@ static int identify_insn(struct insn *insn)
* @umip_inst: A constant indicating the instruction to emulate
* @data: Buffer into which the dummy result is stored
* @data_size: Size of the emulated result
* @x86_64: true if process is 64-bit, false otherwise
*
* Emulate an instruction protected by UMIP and provide a dummy result. The
* result of the emulation is saved in @data. The size of the results depends
@ -202,11 +202,8 @@ static int identify_insn(struct insn *insn)
* 0 on success, -EINVAL on error while emulating.
*/
static int emulate_umip_insn(struct insn *insn, int umip_inst,
unsigned char *data, int *data_size)
unsigned char *data, int *data_size, bool x86_64)
{
unsigned long dummy_base_addr, dummy_value;
unsigned short dummy_limit = 0;
if (!data || !data_size || !insn)
return -EINVAL;
/*
@ -219,6 +216,9 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst,
* is always returned irrespective of the operand size.
*/
if (umip_inst == UMIP_INST_SGDT || umip_inst == UMIP_INST_SIDT) {
u64 dummy_base_addr;
u16 dummy_limit = 0;
/* SGDT and SIDT do not use registers operands. */
if (X86_MODRM_MOD(insn->modrm.value) == 3)
return -EINVAL;
@ -228,13 +228,24 @@ static int emulate_umip_insn(struct insn *insn, int umip_inst,
else
dummy_base_addr = UMIP_DUMMY_IDT_BASE;
*data_size = UMIP_GDT_IDT_LIMIT_SIZE + UMIP_GDT_IDT_BASE_SIZE;
/*
* 64-bit processes use the entire dummy base address.
* 32-bit processes use the lower 32 bits of the base address.
* dummy_base_addr is always 64 bits, but we memcpy the correct
* number of bytes from it to the destination.
*/
if (x86_64)
*data_size = UMIP_GDT_IDT_BASE_SIZE_64BIT;
else
*data_size = UMIP_GDT_IDT_BASE_SIZE_32BIT;
memcpy(data + 2, &dummy_base_addr, UMIP_GDT_IDT_BASE_SIZE);
memcpy(data + 2, &dummy_base_addr, *data_size);
*data_size += UMIP_GDT_IDT_LIMIT_SIZE;
memcpy(data, &dummy_limit, UMIP_GDT_IDT_LIMIT_SIZE);
} else if (umip_inst == UMIP_INST_SMSW) {
dummy_value = CR0_STATE;
unsigned long dummy_value = CR0_STATE;
/*
* Even though the CR0 register has 4 bytes, the number
@ -290,11 +301,10 @@ static void force_sig_info_umip_fault(void __user *addr, struct pt_regs *regs)
* fixup_umip_exception() - Fixup a general protection fault caused by UMIP
* @regs: Registers as saved when entering the #GP handler
*
* The instructions sgdt, sidt, str, smsw, sldt cause a general protection
* fault if executed with CPL > 0 (i.e., from user space). If the offending
* user-space process is not in long mode, this function fixes the exception
* up and provides dummy results for sgdt, sidt and smsw; str and sldt are not
* fixed up. Also long mode user-space processes are not fixed up.
* The instructions SGDT, SIDT, STR, SMSW and SLDT cause a general protection
* fault if executed with CPL > 0 (i.e., from user space). This function fixes
* the exception up and provides dummy results for SGDT, SIDT and SMSW; STR
* and SLDT are not fixed up.
*
* If operands are memory addresses, results are copied to user-space memory as
* indicated by the instruction pointed by eIP using the registers indicated in
@ -373,13 +383,14 @@ bool fixup_umip_exception(struct pt_regs *regs)
umip_pr_warning(regs, "%s instruction cannot be used by applications.\n",
umip_insns[umip_inst]);
/* Do not emulate SLDT, STR or user long mode processes. */
if (umip_inst == UMIP_INST_STR || umip_inst == UMIP_INST_SLDT || user_64bit_mode(regs))
/* Do not emulate (spoof) SLDT or STR. */
if (umip_inst == UMIP_INST_STR || umip_inst == UMIP_INST_SLDT)
return false;
umip_pr_warning(regs, "For now, expensive software emulation returns the result.\n");
if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size))
if (emulate_umip_insn(&insn, umip_inst, dummy_data, &dummy_data_size,
user_64bit_mode(regs)))
return false;
/*

14
arch/x86/lib/copy_user_64.S
View File

@ -33,7 +33,7 @@
102:
.section .fixup,"ax"
103: addl %ecx,%edx /* ecx is zerorest also */
jmp copy_user_handle_tail
jmp .Lcopy_user_handle_tail
.previous
_ASM_EXTABLE_UA(100b, 103b)
@ -113,7 +113,7 @@ ENTRY(copy_user_generic_unrolled)
40: leal (%rdx,%rcx,8),%edx
jmp 60f
50: movl %ecx,%edx
60: jmp copy_user_handle_tail /* ecx is zerorest also */
60: jmp .Lcopy_user_handle_tail /* ecx is zerorest also */
.previous
_ASM_EXTABLE_UA(1b, 30b)
@ -177,7 +177,7 @@ ENTRY(copy_user_generic_string)
.section .fixup,"ax"
11: leal (%rdx,%rcx,8),%ecx
12: movl %ecx,%edx /* ecx is zerorest also */
jmp copy_user_handle_tail
jmp .Lcopy_user_handle_tail
.previous
_ASM_EXTABLE_UA(1b, 11b)
@ -210,7 +210,7 @@ ENTRY(copy_user_enhanced_fast_string)
.section .fixup,"ax"
12: movl %ecx,%edx /* ecx is zerorest also */
jmp copy_user_handle_tail
jmp .Lcopy_user_handle_tail
.previous
_ASM_EXTABLE_UA(1b, 12b)
@ -231,7 +231,7 @@ EXPORT_SYMBOL(copy_user_enhanced_fast_string)
* eax uncopied bytes or 0 if successful.
*/
ALIGN;
copy_user_handle_tail:
.Lcopy_user_handle_tail:
movl %edx,%ecx
1: rep movsb
2: mov %ecx,%eax
@ -239,7 +239,7 @@ copy_user_handle_tail:
ret
_ASM_EXTABLE_UA(1b, 2b)
END(copy_user_handle_tail)
END(.Lcopy_user_handle_tail)
/*
* copy_user_nocache - Uncached memory copy with exception handling
@ -364,7 +364,7 @@ ENTRY(__copy_user_nocache)
movl %ecx,%edx
.L_fixup_handle_tail:
sfence
jmp copy_user_handle_tail
jmp .Lcopy_user_handle_tail
.previous
_ASM_EXTABLE_UA(1b, .L_fixup_4x8b_copy)

16
arch/x86/lib/getuser.S
View File

@ -115,7 +115,7 @@ ENDPROC(__get_user_8)
EXPORT_SYMBOL(__get_user_8)
bad_get_user_clac:
.Lbad_get_user_clac:
ASM_CLAC
bad_get_user:
xor %edx,%edx
@ -123,7 +123,7 @@ bad_get_user:
ret
#ifdef CONFIG_X86_32
bad_get_user_8_clac:
.Lbad_get_user_8_clac:
ASM_CLAC
bad_get_user_8:
xor %edx,%edx
@ -132,12 +132,12 @@ bad_get_user_8:
ret
#endif
_ASM_EXTABLE_UA(1b, bad_get_user_clac)
_ASM_EXTABLE_UA(2b, bad_get_user_clac)
_ASM_EXTABLE_UA(3b, bad_get_user_clac)
_ASM_EXTABLE_UA(1b, .Lbad_get_user_clac)
_ASM_EXTABLE_UA(2b, .Lbad_get_user_clac)
_ASM_EXTABLE_UA(3b, .Lbad_get_user_clac)
#ifdef CONFIG_X86_64
_ASM_EXTABLE_UA(4b, bad_get_user_clac)
_ASM_EXTABLE_UA(4b, .Lbad_get_user_clac)
#else
_ASM_EXTABLE_UA(4b, bad_get_user_8_clac)
_ASM_EXTABLE_UA(5b, bad_get_user_8_clac)
_ASM_EXTABLE_UA(4b, .Lbad_get_user_8_clac)
_ASM_EXTABLE_UA(5b, .Lbad_get_user_8_clac)
#endif

22
arch/x86/lib/putuser.S
View File

@ -37,7 +37,7 @@
ENTRY(__put_user_1)
ENTER
cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
jae bad_put_user
jae .Lbad_put_user
ASM_STAC
1: movb %al,(%_ASM_CX)
xor %eax,%eax
@ -51,7 +51,7 @@ ENTRY(__put_user_2)
mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
sub $1,%_ASM_BX
cmp %_ASM_BX,%_ASM_CX
jae bad_put_user
jae .Lbad_put_user
ASM_STAC
2: movw %ax,(%_ASM_CX)
xor %eax,%eax
@ -65,7 +65,7 @@ ENTRY(__put_user_4)
mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
sub $3,%_ASM_BX
cmp %_ASM_BX,%_ASM_CX
jae bad_put_user
jae .Lbad_put_user
ASM_STAC
3: movl %eax,(%_ASM_CX)
xor %eax,%eax
@ -79,7 +79,7 @@ ENTRY(__put_user_8)
mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
sub $7,%_ASM_BX
cmp %_ASM_BX,%_ASM_CX
jae bad_put_user
jae .Lbad_put_user
ASM_STAC
4: mov %_ASM_AX,(%_ASM_CX)
#ifdef CONFIG_X86_32
@ -91,16 +91,16 @@ ENTRY(__put_user_8)
ENDPROC(__put_user_8)
EXPORT_SYMBOL(__put_user_8)
bad_put_user_clac:
.Lbad_put_user_clac:
ASM_CLAC
bad_put_user:
.Lbad_put_user:
movl $-EFAULT,%eax
RET
_ASM_EXTABLE_UA(1b, bad_put_user_clac)
_ASM_EXTABLE_UA(2b, bad_put_user_clac)
_ASM_EXTABLE_UA(3b, bad_put_user_clac)
_ASM_EXTABLE_UA(4b, bad_put_user_clac)
_ASM_EXTABLE_UA(1b, .Lbad_put_user_clac)
_ASM_EXTABLE_UA(2b, .Lbad_put_user_clac)
_ASM_EXTABLE_UA(3b, .Lbad_put_user_clac)
_ASM_EXTABLE_UA(4b, .Lbad_put_user_clac)
#ifdef CONFIG_X86_32
_ASM_EXTABLE_UA(5b, bad_put_user_clac)
_ASM_EXTABLE_UA(5b, .Lbad_put_user_clac)
#endif