From: Vasily Gorbik Date: Thu, 26 Mar 2026 18:50:14 +0000 (+0100) Subject: s390/entry: Scrub r12 register on kernel entry X-Git-Tag: v7.0-rc6~16^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0738d395aab8fae3b5a3ad3fc640630c91693c27;p=thirdparty%2Fkernel%2Flinux.git s390/entry: Scrub r12 register on kernel entry Before commit f33f2d4c7c80 ("s390/bp: remove TIF_ISOLATE_BP"), all entry handlers loaded r12 with the current task pointer (lg %r12,__LC_CURRENT) for use by the BPENTER/BPEXIT macros. That commit removed TIF_ISOLATE_BP, dropping both the branch prediction macros and the r12 load, but did not add r12 to the register clearing sequence. Add the missing xgr %r12,%r12 to make the register scrub consistent across all entry points. Fixes: f33f2d4c7c80 ("s390/bp: remove TIF_ISOLATE_BP") Cc: stable@kernel.org Reviewed-by: Ilya Leoshkevich Signed-off-by: Vasily Gorbik --- diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 4873fe9d891ba..689d253e1afc7 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -271,6 +271,7 @@ SYM_CODE_START(system_call) xgr %r9,%r9 xgr %r10,%r10 xgr %r11,%r11 + xgr %r12,%r12 la %r2,STACK_FRAME_OVERHEAD(%r15) # pointer to pt_regs mvc __PT_R8(64,%r2),__LC_SAVE_AREA(%r13) MBEAR %r2,%r13 @@ -407,6 +408,7 @@ SYM_CODE_START(\name) xgr %r6,%r6 xgr %r7,%r7 xgr %r10,%r10 + xgr %r12,%r12 xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11) mvc __PT_R8(64,%r11),__LC_SAVE_AREA(%r13) MBEAR %r11,%r13 @@ -496,6 +498,7 @@ SYM_CODE_START(mcck_int_handler) xgr %r6,%r6 xgr %r7,%r7 xgr %r10,%r10 + xgr %r12,%r12 stmg %r8,%r9,__PT_PSW(%r11) xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11) xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)