The patch below does not apply to the 5.11-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b0d31159a46787380353426faaad8febc9bef009 Mon Sep 17 00:00:00 2001
From: Sven Schnelle svens@linux.ibm.com Date: Thu, 28 Jan 2021 13:06:05 +0100 Subject: [PATCH] s390: open code SWITCH_KERNEL macro
This is a preparation patch for two later bugfixes. In the past both int_handler and machine check handler used SWITCH_KERNEL to switch to the kernel stack. However, SWITCH_KERNEL doesn't work properly in machine check context. So instead of adding more complexity to this macro, just remove it.
Signed-off-by: Sven Schnelle svens@linux.ibm.com Cc: stable@kernel.org # v5.8+ Reviewed-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 9b3aea98f886..ed5acf95235f 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -81,32 +81,6 @@ _LPP_OFFSET = __LC_LPP #endif .endm
- .macro SWITCH_KERNEL savearea - tmhh %r8,0x0001 # interrupting from user ? - jnz 1f -#if IS_ENABLED(CONFIG_KVM) - lgr %r14,%r9 - larl %r13,.Lsie_gmap - slgr %r14,%r13 - lghi %r13,.Lsie_done - .Lsie_gmap - clgr %r14,%r13 - jhe 0f - lghi %r11,\savearea # inside critical section, do cleanup - brasl %r14,.Lcleanup_sie -#endif -0: CHECK_STACK \savearea - lgr %r11,%r15 - aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) - stg %r11,__SF_BACKCHAIN(%r15) - j 2f -1: BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP - lctlg %c1,%c1,__LC_KERNEL_ASCE - lg %r15,__LC_KERNEL_STACK - xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) -2: la %r11,STACK_FRAME_OVERHEAD(%r15) - .endm - - # Use STORE CLOCK by default, switch to STORE CLOCK FAST if available. .macro STCK savearea ALTERNATIVE ".insn s,0xb2050000,\savearea", \ ".insn s,0xb27c0000,\savearea", 25 @@ -413,7 +387,28 @@ ENTRY(\name) stmg %r8,%r15,__LC_SAVE_AREA_ASYNC lg %r12,__LC_CURRENT lmg %r8,%r9,\lc_old_psw - SWITCH_KERNEL __LC_SAVE_AREA_ASYNC + tmhh %r8,0x0001 # interrupting from user ? + jnz 1f +#if IS_ENABLED(CONFIG_KVM) + lgr %r14,%r9 + larl %r13,.Lsie_gmap + slgr %r14,%r13 + lghi %r13,.Lsie_done - .Lsie_gmap + clgr %r14,%r13 + jhe 0f + lghi %r11,__LC_SAVE_AREA_ASYNC # inside critical section, do cleanup + brasl %r14,.Lcleanup_sie +#endif +0: CHECK_STACK __LC_SAVE_AREA_ASYNC + lgr %r11,%r15 + aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) + stg %r11,__SF_BACKCHAIN(%r15) + j 2f +1: BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP + lctlg %c1,%c1,__LC_KERNEL_ASCE + lg %r15,__LC_KERNEL_STACK + xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) +2: la %r11,STACK_FRAME_OVERHEAD(%r15) stmg %r0,%r7,__PT_R0(%r11) # clear user controlled registers to prevent speculative use xgr %r0,%r0 @@ -542,7 +537,30 @@ ENTRY(mcck_int_handler) TSTMSK __LC_MCCK_CODE,MCCK_CODE_PSW_IA_VALID jno .Lmcck_panic 4: ssm __LC_PGM_NEW_PSW # turn dat on, keep irqs off - SWITCH_KERNEL __LC_GPREGS_SAVE_AREA+64 + tmhh %r8,0x0001 # interrupting from user ? + jnz .Lmcck_user +#if IS_ENABLED(CONFIG_KVM) + lgr %r14,%r9 + larl %r13,.Lsie_gmap + slgr %r14,%r13 + lghi %r13,.Lsie_done - .Lsie_gmap + clgr %r14,%r13 + jhe .Lmcck_stack + lghi %r11,__LC_GPREGS_SAVE_AREA+64 # inside critical section, do cleanup + brasl %r14,.Lcleanup_sie +.Lmcck_stack: +#endif + CHECK_STACK __LC_GPREGS_SAVE_AREA+64 + lgr %r11,%r15 + aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) + stg %r11,__SF_BACKCHAIN(%r15) + j 5f +.Lmcck_user: + BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP + lctlg %c1,%c1,__LC_KERNEL_ASCE + lg %r15,__LC_KERNEL_STACK + xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) +5: la %r11,STACK_FRAME_OVERHEAD(%r15) .Lmcck_skip: lghi %r14,__LC_GPREGS_SAVE_AREA+64 stmg %r0,%r7,__PT_R0(%r11)