From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id F359F1A0EB8 for ; Tue, 26 May 2015 15:46:57 +1000 (AEST) From: Anton Blanchard To: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, mikey@neuling.org Cc: linuxppc-dev@lists.ozlabs.org Subject: [PATCH 1/2] powerpc: Relocatable system call no longer uses the LR Date: Tue, 26 May 2015 15:46:54 +1000 Message-Id: <1432619215-13490-1-git-send-email-anton@samba.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , We had some code to restore the LR in the relocatable system call path back when we used the LR to do an indirect branch. Commit 6a404806dfce ("powerpc: Avoid link stack corruption in MMU on syscall entry path") changed this to use the CTR which is volatile across system calls so does not need restoring. Remove the stale comment and the restore of the LR. Signed-off-by: Anton Blanchard --- arch/powerpc/kernel/exceptions-64s.S | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 9519e6b..cf8c1b5 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -59,14 +59,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \ #if defined(CONFIG_RELOCATABLE) /* - * We can't branch directly; in the direct case we use LR - * and system_call_entry restores LR. (We thus need to move - * LR to r10 in the RFID case too.) + * We can't branch directly so we do it via the CTR which + * is volatile across system calls. */ #define SYSCALL_PSERIES_2_DIRECT \ mflr r10 ; \ ld r12,PACAKBASE(r13) ; \ - LOAD_HANDLER(r12, system_call_entry_direct) ; \ + LOAD_HANDLER(r12, system_call_entry) ; \ mtctr r12 ; \ mfspr r12,SPRN_SRR1 ; \ /* Re-use of r13... No spare regs to do this */ \ @@ -80,7 +79,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \ mfspr r12,SPRN_SRR1 ; \ li r10,MSR_RI ; \ mtmsrd r10,1 ; /* Set RI (EE=0) */ \ - b system_call_entry_direct ; + b system_call_entry ; #endif /* @@ -969,13 +968,6 @@ hv_facility_unavailable_relon_trampoline: __end_interrupts: .align 7 -system_call_entry_direct: -#if defined(CONFIG_RELOCATABLE) - /* The first level prologue may have used LR to get here, saving - * orig in r10. To save hacking/ifdeffing common code, restore here. - */ - mtlr r10 -#endif system_call_entry: b system_call_common -- 2.1.4