Commit c6ac667b authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64e/interrupt: Fix nvgprs being clobbered 



Some interrupt handlers have an "extra" that saves 1 or 2
registers (r14, r15) in the paca save area and makes them available to
use by the handler.

The change to always save nvgprs in exception handlers lead to some
interrupt handlers saving those scratch r14 / r15 registers into the
interrupt frame's GPR saves, which get restored on interrupt exit.

Fix this by always reloading those scratch registers from paca before
the EXCEPTION_COMMON that saves nvgprs.

Fixes: 4228b2c3 ("powerpc/64e/interrupt: always save nvgprs on interrupt")
Reported-by: default avatarChristian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Tested-by: default avatarChristian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210514044008.1955783-1-npiggin@gmail.com
parent 4ec5feec

arch/powerpc/kernel/exceptions-64e.S

+24 −14
Original line number Diff line number Diff line
@@ -340,6 +340,12 @@ ret_from_mc_except: 
	andi.	r10,r10,IRQS_DISABLED;	/* yes -> go out of line */ \

	bne	masked_interrupt_book3e_##n



/*

 * Additional regs must be re-loaded from paca before EXCEPTION_COMMON* is

 * called, because that does SAVE_NVGPRS which must see the original register

 * values, otherwise the scratch values might be restored when exiting the

 * interrupt.

 */

#define PROLOG_ADDITION_2REGS_GEN(n)					    \

	std	r14,PACA_EXGEN+EX_R14(r13);				    \

	std	r15,PACA_EXGEN+EX_R15(r13)
@@ -535,6 +541,10 @@ __end_interrupts: 
				PROLOG_ADDITION_2REGS)

	mfspr	r14,SPRN_DEAR

	mfspr	r15,SPRN_ESR

	std	r14,_DAR(r1)

	std	r15,_DSISR(r1)

	ld	r14,PACA_EXGEN+EX_R14(r13)

	ld	r15,PACA_EXGEN+EX_R15(r13)

	EXCEPTION_COMMON(0x300)

	b	storage_fault_common
@@ -544,6 +554,10 @@ __end_interrupts: 
				PROLOG_ADDITION_2REGS)

	li	r15,0

	mr	r14,r10

	std	r14,_DAR(r1)

	std	r15,_DSISR(r1)

	ld	r14,PACA_EXGEN+EX_R14(r13)

	ld	r15,PACA_EXGEN+EX_R15(r13)

	EXCEPTION_COMMON(0x400)

	b	storage_fault_common
@@ -557,6 +571,10 @@ __end_interrupts: 
				PROLOG_ADDITION_2REGS)

	mfspr	r14,SPRN_DEAR

	mfspr	r15,SPRN_ESR

	std	r14,_DAR(r1)

	std	r15,_DSISR(r1)

	ld	r14,PACA_EXGEN+EX_R14(r13)

	ld	r15,PACA_EXGEN+EX_R15(r13)

	EXCEPTION_COMMON(0x600)

	b	alignment_more	/* no room, go out of line */
@@ -565,10 +583,10 @@ __end_interrupts: 
	NORMAL_EXCEPTION_PROLOG(0x700, BOOKE_INTERRUPT_PROGRAM,

				PROLOG_ADDITION_1REG)

	mfspr	r14,SPRN_ESR

	EXCEPTION_COMMON(0x700)

	std	r14,_DSISR(r1)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	ld	r14,PACA_EXGEN+EX_R14(r13)

	EXCEPTION_COMMON(0x700)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	bl	program_check_exception

	REST_NVGPRS(r1)

	b	interrupt_return
@@ -725,11 +743,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC) 
	 * normal exception

	 */

	mfspr	r14,SPRN_DBSR

	EXCEPTION_COMMON_CRIT(0xd00)

	std	r14,_DSISR(r1)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	ld	r14,PACA_EXCRIT+EX_R14(r13)

	ld	r15,PACA_EXCRIT+EX_R15(r13)

	EXCEPTION_COMMON_CRIT(0xd00)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	bl	DebugException

	REST_NVGPRS(r1)

	b	interrupt_return
@@ -796,11 +814,11 @@ kernel_dbg_exc: 
	 * normal exception

	 */

	mfspr	r14,SPRN_DBSR

	EXCEPTION_COMMON_DBG(0xd08)

	std	r14,_DSISR(r1)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	ld	r14,PACA_EXDBG+EX_R14(r13)

	ld	r15,PACA_EXDBG+EX_R15(r13)

	EXCEPTION_COMMON_DBG(0xd08)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	bl	DebugException

	REST_NVGPRS(r1)

	b	interrupt_return
@@ -931,11 +949,7 @@ masked_interrupt_book3e_0x2c0: 
 * original values stashed away in the PACA

 */

storage_fault_common:

	std	r14,_DAR(r1)

	std	r15,_DSISR(r1)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	ld	r14,PACA_EXGEN+EX_R14(r13)

	ld	r15,PACA_EXGEN+EX_R15(r13)

	bl	do_page_fault

	b	interrupt_return
@@ -944,11 +958,7 @@ storage_fault_common: 
 * continues here.

 */

alignment_more:

	std	r14,_DAR(r1)

	std	r15,_DSISR(r1)

	addi	r3,r1,STACK_FRAME_OVERHEAD

	ld	r14,PACA_EXGEN+EX_R14(r13)

	ld	r15,PACA_EXGEN+EX_R15(r13)

	bl	alignment_exception

	REST_NVGPRS(r1)

	b	interrupt_return