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linux-stable/arch/powerpc/kernel/interrupt_64.S
Naveen N Rao 76d3ad7d02 powerpc/64: Set task pt_regs->link to the LR value on scv entry 
commit aad98efd0b upstream.

Nysal reported that userspace backtraces are missing in offcputime bcc
tool. As an example:
    $ sudo ./bcc/tools/offcputime.py -uU
    Tracing off-CPU time (us) of user threads by user stack... Hit Ctrl-C to end.

    ^C
	write
	-                python (9107)
	    8

	write
	-                sudo (9105)
	    9

	mmap
	-                python (9107)
	    16

	clock_nanosleep
	-                multipathd (697)
	    3001604

The offcputime bcc tool attaches a bpf program to a kprobe on
finish_task_switch(), which is usually hit on a syscall from userspace.
With the switch to system call vectored, we started setting
pt_regs->link to zero. This is because system call vectored behaves like
a function call with LR pointing to the system call return address, and
with no modification to SRR0/SRR1. The LR value does indicate our next
instruction, so it is being saved as pt_regs->nip, and pt_regs->link is
being set to zero. This is not a problem by itself, but BPF uses perf
callchain infrastructure for capturing stack traces, and that stores LR
as the second entry in the stack trace. perf has code to cope with the
second entry being zero, and skips over it. However, generic userspace
unwinders assume that a zero entry indicates end of the stack trace,
resulting in a truncated userspace stack trace.

Rather than fixing all userspace unwinders to ignore/skip past the
second entry, store the real LR value in pt_regs->link so that there
continues to be a valid, though duplicate entry in the stack trace.

With this change:
    $ sudo ./bcc/tools/offcputime.py -uU
    Tracing off-CPU time (us) of user threads by user stack... Hit Ctrl-C to end.

    ^C
	write
	write
	[unknown]
	[unknown]
	[unknown]
	[unknown]
	[unknown]
	PyObject_VectorcallMethod
	[unknown]
	[unknown]
	PyObject_CallOneArg
	PyFile_WriteObject
	PyFile_WriteString
	[unknown]
	[unknown]
	PyObject_Vectorcall
	_PyEval_EvalFrameDefault
	PyEval_EvalCode
	[unknown]
	[unknown]
	[unknown]
	_PyRun_SimpleFileObject
	_PyRun_AnyFileObject
	Py_RunMain
	[unknown]
	Py_BytesMain
	[unknown]
	__libc_start_main
	-                python (1293)
	    7

	write
	write
	[unknown]
	sudo_ev_loop_v1
	sudo_ev_dispatch_v1
	[unknown]
	[unknown]
	[unknown]
	[unknown]
	__libc_start_main
	-                sudo (1291)
	    7

	syscall
	syscall
	bpf_open_perf_buffer_opts
	[unknown]
	[unknown]
	[unknown]
	[unknown]
	_PyObject_MakeTpCall
	PyObject_Vectorcall
	_PyEval_EvalFrameDefault
	PyEval_EvalCode
	[unknown]
	[unknown]
	[unknown]
	_PyRun_SimpleFileObject
	_PyRun_AnyFileObject
	Py_RunMain
	[unknown]
	Py_BytesMain
	[unknown]
	__libc_start_main
	-                python (1293)
	    11

	clock_nanosleep
	clock_nanosleep
	nanosleep
	sleep
	[unknown]
	[unknown]
	__clone
	-                multipathd (698)
	    3001661

Fixes: 7fa95f9ada ("powerpc/64s: system call support for scv/rfscv instructions")
Cc: stable@vger.kernel.org
Reported-by: "Nysal Jan K.A" <nysal@linux.ibm.com>
Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240202154316.395276-1-naveen@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-02-23 09:12:42 +01:00

734 lines
17 KiB
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#include <asm/asm-offsets.h>
#include <asm/bug.h>
#ifdef CONFIG_PPC_BOOK3S
#include <asm/exception-64s.h>
#else
#include <asm/exception-64e.h>
#endif
#include <asm/feature-fixups.h>
#include <asm/head-64.h>
#include <asm/hw_irq.h>
#include <asm/kup.h>
#include <asm/mmu.h>
#include <asm/ppc_asm.h>
#include <asm/ptrace.h>
.align 7
.macro DEBUG_SRR_VALID srr
#ifdef CONFIG_PPC_RFI_SRR_DEBUG
.ifc \srr,srr
mfspr r11,SPRN_SRR0
ld r12,_NIP(r1)
clrrdi r11,r11,2
clrrdi r12,r12,2
100: tdne r11,r12
EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
mfspr r11,SPRN_SRR1
ld r12,_MSR(r1)
100: tdne r11,r12
EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
.else
mfspr r11,SPRN_HSRR0
ld r12,_NIP(r1)
clrrdi r11,r11,2
clrrdi r12,r12,2
100: tdne r11,r12
EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
mfspr r11,SPRN_HSRR1
ld r12,_MSR(r1)
100: tdne r11,r12
EMIT_WARN_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE)
.endif
#endif
.endm
#ifdef CONFIG_PPC_BOOK3S
.macro system_call_vectored name trapnr
.globl system_call_vectored_\name
system_call_vectored_\name:
_ASM_NOKPROBE_SYMBOL(system_call_vectored_\name)
SCV_INTERRUPT_TO_KERNEL
mr r10,r1
ld r1,PACAKSAVE(r13)
std r10,0(r1)
std r11,_LINK(r1)
std r11,_NIP(r1) /* Saved LR is also the next instruction */
std r12,_MSR(r1)
std r0,GPR0(r1)
std r10,GPR1(r1)
std r2,GPR2(r1)
LOAD_PACA_TOC()
mfcr r12
li r11,0
/* Save syscall parameters in r3-r8 */
SAVE_GPRS(3, 8, r1)
/* Zero r9-r12, this should only be required when restoring all GPRs */
std r11,GPR9(r1)
std r11,GPR10(r1)
std r11,GPR11(r1)
std r11,GPR12(r1)
std r9,GPR13(r1)
SAVE_NVGPRS(r1)
std r11,_XER(r1)
std r11,_CTR(r1)
li r11,\trapnr
std r11,_TRAP(r1)
std r12,_CCR(r1)
std r3,ORIG_GPR3(r1)
/* Calling convention has r3 = regs, r4 = orig r0 */
addi r3,r1,STACK_FRAME_OVERHEAD
mr r4,r0
LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
std r11,-16(r3) /* "regshere" marker */
BEGIN_FTR_SECTION
HMT_MEDIUM
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
/*
* scv enters with MSR[EE]=1 and is immediately considered soft-masked.
* The entry vector already sets PACAIRQSOFTMASK to IRQS_ALL_DISABLED,
* and interrupts may be masked and pending already.
* system_call_exception() will call trace_hardirqs_off() which means
* interrupts could already have been blocked before trace_hardirqs_off,
* but this is the best we can do.
*/
bl system_call_exception
.Lsyscall_vectored_\name\()_exit:
addi r4,r1,STACK_FRAME_OVERHEAD
li r5,1 /* scv */
bl syscall_exit_prepare
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
.Lsyscall_vectored_\name\()_rst_start:
lbz r11,PACAIRQHAPPENED(r13)
andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
bne- syscall_vectored_\name\()_restart
li r11,IRQS_ENABLED
stb r11,PACAIRQSOFTMASK(r13)
li r11,0
stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS
ld r2,_CCR(r1)
ld r4,_NIP(r1)
ld r5,_MSR(r1)
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
BEGIN_FTR_SECTION
HMT_MEDIUM_LOW
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
cmpdi r3,0
bne .Lsyscall_vectored_\name\()_restore_regs
/* rfscv returns with LR->NIA and CTR->MSR */
mtlr r4
mtctr r5
/* Could zero these as per ABI, but we may consider a stricter ABI
* which preserves these if libc implementations can benefit, so
* restore them for now until further measurement is done. */
REST_GPR(0, r1)
REST_GPRS(4, 8, r1)
/* Zero volatile regs that may contain sensitive kernel data */
ZEROIZE_GPRS(9, 12)
mtspr SPRN_XER,r0
/*
* We don't need to restore AMR on the way back to userspace for KUAP.
* The value of AMR only matters while we're in the kernel.
*/
mtcr r2
REST_GPRS(2, 3, r1)
REST_GPR(13, r1)
REST_GPR(1, r1)
RFSCV_TO_USER
b . /* prevent speculative execution */
.Lsyscall_vectored_\name\()_restore_regs:
mtspr SPRN_SRR0,r4
mtspr SPRN_SRR1,r5
ld r3,_CTR(r1)
ld r4,_LINK(r1)
ld r5,_XER(r1)
REST_NVGPRS(r1)
REST_GPR(0, r1)
mtcr r2
mtctr r3
mtlr r4
mtspr SPRN_XER,r5
REST_GPRS(2, 13, r1)
REST_GPR(1, r1)
RFI_TO_USER
.Lsyscall_vectored_\name\()_rst_end:
syscall_vectored_\name\()_restart:
_ASM_NOKPROBE_SYMBOL(syscall_vectored_\name\()_restart)
GET_PACA(r13)
ld r1,PACA_EXIT_SAVE_R1(r13)
LOAD_PACA_TOC()
ld r3,RESULT(r1)
addi r4,r1,STACK_FRAME_OVERHEAD
li r11,IRQS_ALL_DISABLED
stb r11,PACAIRQSOFTMASK(r13)
bl syscall_exit_restart
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
b .Lsyscall_vectored_\name\()_rst_start
1:
SOFT_MASK_TABLE(.Lsyscall_vectored_\name\()_rst_start, 1b)
RESTART_TABLE(.Lsyscall_vectored_\name\()_rst_start, .Lsyscall_vectored_\name\()_rst_end, syscall_vectored_\name\()_restart)
.endm
system_call_vectored common 0x3000
/*
* We instantiate another entry copy for the SIGILL variant, with TRAP=0x7ff0
* which is tested by system_call_exception when r0 is -1 (as set by vector
* entry code).
*/
system_call_vectored sigill 0x7ff0
#endif /* CONFIG_PPC_BOOK3S */
.balign IFETCH_ALIGN_BYTES
.globl system_call_common_real
system_call_common_real:
_ASM_NOKPROBE_SYMBOL(system_call_common_real)
ld r10,PACAKMSR(r13) /* get MSR value for kernel */
mtmsrd r10
.balign IFETCH_ALIGN_BYTES
.globl system_call_common
system_call_common:
_ASM_NOKPROBE_SYMBOL(system_call_common)
mr r10,r1
ld r1,PACAKSAVE(r13)
std r10,0(r1)
std r11,_NIP(r1)
std r12,_MSR(r1)
std r0,GPR0(r1)
std r10,GPR1(r1)
std r2,GPR2(r1)
#ifdef CONFIG_PPC_E500
START_BTB_FLUSH_SECTION
BTB_FLUSH(r10)
END_BTB_FLUSH_SECTION
#endif
LOAD_PACA_TOC()
mfcr r12
li r11,0
/* Save syscall parameters in r3-r8 */
SAVE_GPRS(3, 8, r1)
/* Zero r9-r12, this should only be required when restoring all GPRs */
std r11,GPR9(r1)
std r11,GPR10(r1)
std r11,GPR11(r1)
std r11,GPR12(r1)
std r9,GPR13(r1)
SAVE_NVGPRS(r1)
std r11,_XER(r1)
std r11,_CTR(r1)
mflr r10
/*
* This clears CR0.SO (bit 28), which is the error indication on
* return from this system call.
*/
rldimi r12,r11,28,(63-28)
li r11,0xc00
std r10,_LINK(r1)
std r11,_TRAP(r1)
std r12,_CCR(r1)
std r3,ORIG_GPR3(r1)
/* Calling convention has r3 = regs, r4 = orig r0 */
addi r3,r1,STACK_FRAME_OVERHEAD
mr r4,r0
LOAD_REG_IMMEDIATE(r11, STACK_FRAME_REGS_MARKER)
std r11,-16(r3) /* "regshere" marker */
#ifdef CONFIG_PPC_BOOK3S
li r11,1
stb r11,PACASRR_VALID(r13)
#endif
/*
* We always enter kernel from userspace with irq soft-mask enabled and
* nothing pending. system_call_exception() will call
* trace_hardirqs_off().
*/
li r11,IRQS_ALL_DISABLED
stb r11,PACAIRQSOFTMASK(r13)
#ifdef CONFIG_PPC_BOOK3S
li r12,-1 /* Set MSR_EE and MSR_RI */
mtmsrd r12,1
#else
wrteei 1
#endif
bl system_call_exception
.Lsyscall_exit:
addi r4,r1,STACK_FRAME_OVERHEAD
li r5,0 /* !scv */
bl syscall_exit_prepare
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
#ifdef CONFIG_PPC_BOOK3S
.Lsyscall_rst_start:
lbz r11,PACAIRQHAPPENED(r13)
andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
bne- syscall_restart
#endif
li r11,IRQS_ENABLED
stb r11,PACAIRQSOFTMASK(r13)
li r11,0
stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS
ld r2,_CCR(r1)
ld r6,_LINK(r1)
mtlr r6
#ifdef CONFIG_PPC_BOOK3S
lbz r4,PACASRR_VALID(r13)
cmpdi r4,0
bne 1f
li r4,0
stb r4,PACASRR_VALID(r13)
#endif
ld r4,_NIP(r1)
ld r5,_MSR(r1)
mtspr SPRN_SRR0,r4
mtspr SPRN_SRR1,r5
1:
DEBUG_SRR_VALID srr
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
END_FTR_SECTION_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
cmpdi r3,0
bne .Lsyscall_restore_regs
/* Zero volatile regs that may contain sensitive kernel data */
ZEROIZE_GPR(0)
ZEROIZE_GPRS(4, 12)
mtctr r0
mtspr SPRN_XER,r0
.Lsyscall_restore_regs_cont:
BEGIN_FTR_SECTION
HMT_MEDIUM_LOW
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
/*
* We don't need to restore AMR on the way back to userspace for KUAP.
* The value of AMR only matters while we're in the kernel.
*/
mtcr r2
REST_GPRS(2, 3, r1)
REST_GPR(13, r1)
REST_GPR(1, r1)
RFI_TO_USER
b . /* prevent speculative execution */
.Lsyscall_restore_regs:
ld r3,_CTR(r1)
ld r4,_XER(r1)
REST_NVGPRS(r1)
mtctr r3
mtspr SPRN_XER,r4
REST_GPR(0, r1)
REST_GPRS(4, 12, r1)
b .Lsyscall_restore_regs_cont
.Lsyscall_rst_end:
#ifdef CONFIG_PPC_BOOK3S
syscall_restart:
_ASM_NOKPROBE_SYMBOL(syscall_restart)
GET_PACA(r13)
ld r1,PACA_EXIT_SAVE_R1(r13)
LOAD_PACA_TOC()
ld r3,RESULT(r1)
addi r4,r1,STACK_FRAME_OVERHEAD
li r11,IRQS_ALL_DISABLED
stb r11,PACAIRQSOFTMASK(r13)
bl syscall_exit_restart
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
b .Lsyscall_rst_start
1:
SOFT_MASK_TABLE(.Lsyscall_rst_start, 1b)
RESTART_TABLE(.Lsyscall_rst_start, .Lsyscall_rst_end, syscall_restart)
#endif
/*
* If MSR EE/RI was never enabled, IRQs not reconciled, NVGPRs not
* touched, no exit work created, then this can be used.
*/
.balign IFETCH_ALIGN_BYTES
.globl fast_interrupt_return_srr
fast_interrupt_return_srr:
_ASM_NOKPROBE_SYMBOL(fast_interrupt_return_srr)
kuap_check_amr r3, r4
ld r5,_MSR(r1)
andi. r0,r5,MSR_PR
#ifdef CONFIG_PPC_BOOK3S
beq 1f
kuap_user_restore r3, r4
b .Lfast_user_interrupt_return_srr
1: kuap_kernel_restore r3, r4
andi. r0,r5,MSR_RI
li r3,0 /* 0 return value, no EMULATE_STACK_STORE */
bne+ .Lfast_kernel_interrupt_return_srr
addi r3,r1,STACK_FRAME_OVERHEAD
bl unrecoverable_exception
b . /* should not get here */
#else
bne .Lfast_user_interrupt_return_srr
b .Lfast_kernel_interrupt_return_srr
#endif
.macro interrupt_return_macro srr
.balign IFETCH_ALIGN_BYTES
.globl interrupt_return_\srr
interrupt_return_\srr\():
_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\())
ld r4,_MSR(r1)
andi. r0,r4,MSR_PR
beq interrupt_return_\srr\()_kernel
interrupt_return_\srr\()_user: /* make backtraces match the _kernel variant */
_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\()_user)
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_user_prepare
cmpdi r3,0
bne- .Lrestore_nvgprs_\srr
.Lrestore_nvgprs_\srr\()_cont:
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
#ifdef CONFIG_PPC_BOOK3S
.Linterrupt_return_\srr\()_user_rst_start:
lbz r11,PACAIRQHAPPENED(r13)
andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
bne- interrupt_return_\srr\()_user_restart
#endif
li r11,IRQS_ENABLED
stb r11,PACAIRQSOFTMASK(r13)
li r11,0
stb r11,PACAIRQHAPPENED(r13) # clear out possible HARD_DIS
.Lfast_user_interrupt_return_\srr\():
#ifdef CONFIG_PPC_BOOK3S
.ifc \srr,srr
lbz r4,PACASRR_VALID(r13)
.else
lbz r4,PACAHSRR_VALID(r13)
.endif
cmpdi r4,0
li r4,0
bne 1f
#endif
ld r11,_NIP(r1)
ld r12,_MSR(r1)
.ifc \srr,srr
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r12
1:
#ifdef CONFIG_PPC_BOOK3S
stb r4,PACASRR_VALID(r13)
#endif
.else
mtspr SPRN_HSRR0,r11
mtspr SPRN_HSRR1,r12
1:
#ifdef CONFIG_PPC_BOOK3S
stb r4,PACAHSRR_VALID(r13)
#endif
.endif
DEBUG_SRR_VALID \srr
#ifdef CONFIG_PPC_IRQ_SOFT_MASK_DEBUG
lbz r4,PACAIRQSOFTMASK(r13)
tdnei r4,IRQS_ENABLED
#endif
BEGIN_FTR_SECTION
ld r10,_PPR(r1)
mtspr SPRN_PPR,r10
END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
FTR_SECTION_ELSE
ldarx r0,0,r1
ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
ld r3,_CCR(r1)
ld r4,_LINK(r1)
ld r5,_CTR(r1)
ld r6,_XER(r1)
li r0,0
REST_GPRS(7, 13, r1)
mtcr r3
mtlr r4
mtctr r5
mtspr SPRN_XER,r6
REST_GPRS(2, 6, r1)
REST_GPR(0, r1)
REST_GPR(1, r1)
.ifc \srr,srr
RFI_TO_USER
.else
HRFI_TO_USER
.endif
b . /* prevent speculative execution */
.Linterrupt_return_\srr\()_user_rst_end:
.Lrestore_nvgprs_\srr\():
REST_NVGPRS(r1)
b .Lrestore_nvgprs_\srr\()_cont
#ifdef CONFIG_PPC_BOOK3S
interrupt_return_\srr\()_user_restart:
_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\()_user_restart)
GET_PACA(r13)
ld r1,PACA_EXIT_SAVE_R1(r13)
LOAD_PACA_TOC()
addi r3,r1,STACK_FRAME_OVERHEAD
li r11,IRQS_ALL_DISABLED
stb r11,PACAIRQSOFTMASK(r13)
bl interrupt_exit_user_restart
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
b .Linterrupt_return_\srr\()_user_rst_start
1:
SOFT_MASK_TABLE(.Linterrupt_return_\srr\()_user_rst_start, 1b)
RESTART_TABLE(.Linterrupt_return_\srr\()_user_rst_start, .Linterrupt_return_\srr\()_user_rst_end, interrupt_return_\srr\()_user_restart)
#endif
.balign IFETCH_ALIGN_BYTES
interrupt_return_\srr\()_kernel:
_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\()_kernel)
addi r3,r1,STACK_FRAME_OVERHEAD
bl interrupt_exit_kernel_prepare
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
.Linterrupt_return_\srr\()_kernel_rst_start:
ld r11,SOFTE(r1)
cmpwi r11,IRQS_ENABLED
stb r11,PACAIRQSOFTMASK(r13)
beq .Linterrupt_return_\srr\()_soft_enabled
/*
* Returning to soft-disabled context.
* Check if a MUST_HARD_MASK interrupt has become pending, in which
* case we need to disable MSR[EE] in the return context.
*
* The MSR[EE] check catches among other things the short incoherency
* in hard_irq_disable() between clearing MSR[EE] and setting
* PACA_IRQ_HARD_DIS.
*/
ld r12,_MSR(r1)
andi. r10,r12,MSR_EE
beq .Lfast_kernel_interrupt_return_\srr\() // EE already disabled
lbz r11,PACAIRQHAPPENED(r13)
andi. r10,r11,PACA_IRQ_MUST_HARD_MASK
bne 1f // HARD_MASK is pending
// No HARD_MASK pending, clear possible HARD_DIS set by interrupt
andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
stb r11,PACAIRQHAPPENED(r13)
b .Lfast_kernel_interrupt_return_\srr\()
1: /* Must clear MSR_EE from _MSR */
#ifdef CONFIG_PPC_BOOK3S
li r10,0
/* Clear valid before changing _MSR */
.ifc \srr,srr
stb r10,PACASRR_VALID(r13)
.else
stb r10,PACAHSRR_VALID(r13)
.endif
#endif
xori r12,r12,MSR_EE
std r12,_MSR(r1)
b .Lfast_kernel_interrupt_return_\srr\()
.Linterrupt_return_\srr\()_soft_enabled:
/*
* In the soft-enabled case, need to double-check that we have no
* pending interrupts that might have come in before we reached the
* restart section of code, and restart the exit so those can be
* handled.
*
* If there are none, it is be possible that the interrupt still
* has PACA_IRQ_HARD_DIS set, which needs to be cleared for the
* interrupted context. This clear will not clobber a new pending
* interrupt coming in, because we're in the restart section, so
* such would return to the restart location.
*/
#ifdef CONFIG_PPC_BOOK3S
lbz r11,PACAIRQHAPPENED(r13)
andi. r11,r11,(~PACA_IRQ_HARD_DIS)@l
bne- interrupt_return_\srr\()_kernel_restart
#endif
li r11,0
stb r11,PACAIRQHAPPENED(r13) // clear the possible HARD_DIS
.Lfast_kernel_interrupt_return_\srr\():
cmpdi cr1,r3,0
#ifdef CONFIG_PPC_BOOK3S
.ifc \srr,srr
lbz r4,PACASRR_VALID(r13)
.else
lbz r4,PACAHSRR_VALID(r13)
.endif
cmpdi r4,0
li r4,0
bne 1f
#endif
ld r11,_NIP(r1)
ld r12,_MSR(r1)
.ifc \srr,srr
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r12
1:
#ifdef CONFIG_PPC_BOOK3S
stb r4,PACASRR_VALID(r13)
#endif
.else
mtspr SPRN_HSRR0,r11
mtspr SPRN_HSRR1,r12
1:
#ifdef CONFIG_PPC_BOOK3S
stb r4,PACAHSRR_VALID(r13)
#endif
.endif
DEBUG_SRR_VALID \srr
BEGIN_FTR_SECTION
stdcx. r0,0,r1 /* to clear the reservation */
FTR_SECTION_ELSE
ldarx r0,0,r1
ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
ld r3,_LINK(r1)
ld r4,_CTR(r1)
ld r5,_XER(r1)
ld r6,_CCR(r1)
li r0,0
REST_GPRS(7, 12, r1)
mtlr r3
mtctr r4
mtspr SPRN_XER,r5
/*
* Leaving a stale STACK_FRAME_REGS_MARKER on the stack can confuse
* the reliable stack unwinder later on. Clear it.
*/
std r0,STACK_FRAME_OVERHEAD-16(r1)
REST_GPRS(2, 5, r1)
bne- cr1,1f /* emulate stack store */
mtcr r6
REST_GPR(6, r1)
REST_GPR(0, r1)
REST_GPR(1, r1)
.ifc \srr,srr
RFI_TO_KERNEL
.else
HRFI_TO_KERNEL
.endif
b . /* prevent speculative execution */
1: /*
* Emulate stack store with update. New r1 value was already calculated
* and updated in our interrupt regs by emulate_loadstore, but we can't
* store the previous value of r1 to the stack before re-loading our
* registers from it, otherwise they could be clobbered. Use
* PACA_EXGEN as temporary storage to hold the store data, as
* interrupts are disabled here so it won't be clobbered.
*/
mtcr r6
std r9,PACA_EXGEN+0(r13)
addi r9,r1,INT_FRAME_SIZE /* get original r1 */
REST_GPR(6, r1)
REST_GPR(0, r1)
REST_GPR(1, r1)
std r9,0(r1) /* perform store component of stdu */
ld r9,PACA_EXGEN+0(r13)
.ifc \srr,srr
RFI_TO_KERNEL
.else
HRFI_TO_KERNEL
.endif
b . /* prevent speculative execution */
.Linterrupt_return_\srr\()_kernel_rst_end:
#ifdef CONFIG_PPC_BOOK3S
interrupt_return_\srr\()_kernel_restart:
_ASM_NOKPROBE_SYMBOL(interrupt_return_\srr\()_kernel_restart)
GET_PACA(r13)
ld r1,PACA_EXIT_SAVE_R1(r13)
LOAD_PACA_TOC()
addi r3,r1,STACK_FRAME_OVERHEAD
li r11,IRQS_ALL_DISABLED
stb r11,PACAIRQSOFTMASK(r13)
bl interrupt_exit_kernel_restart
std r1,PACA_EXIT_SAVE_R1(r13) /* save r1 for restart */
b .Linterrupt_return_\srr\()_kernel_rst_start
1:
SOFT_MASK_TABLE(.Linterrupt_return_\srr\()_kernel_rst_start, 1b)
RESTART_TABLE(.Linterrupt_return_\srr\()_kernel_rst_start, .Linterrupt_return_\srr\()_kernel_rst_end, interrupt_return_\srr\()_kernel_restart)
#endif
.endm
interrupt_return_macro srr
#ifdef CONFIG_PPC_BOOK3S
interrupt_return_macro hsrr
.globl __end_soft_masked
__end_soft_masked:
DEFINE_FIXED_SYMBOL(__end_soft_masked, text)
#endif /* CONFIG_PPC_BOOK3S */
#ifdef CONFIG_PPC_BOOK3S
_GLOBAL(ret_from_fork_scv)
bl schedule_tail
REST_NVGPRS(r1)
li r3,0 /* fork() return value */
b .Lsyscall_vectored_common_exit
#endif
_GLOBAL(ret_from_fork)
bl schedule_tail
REST_NVGPRS(r1)
li r3,0 /* fork() return value */
b .Lsyscall_exit
_GLOBAL(ret_from_kernel_thread)
bl schedule_tail
REST_NVGPRS(r1)
mtctr r14
mr r3,r15
#ifdef CONFIG_PPC64_ELF_ABI_V2
mr r12,r14
#endif
bctrl
li r3,0
b .Lsyscall_exit
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