From: Naveen N. Rao Date: Wed, 19 Apr 2017 12:52:24 +0000 (+0530) Subject: powerpc/ftrace: Restore LR from pt_regs X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2f59be5b970b503ca8db1cb723b155e455ebac8e;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git powerpc/ftrace: Restore LR from pt_regs Pass the real LR to the ftrace handler. This is needed for KPROBES_ON_FTRACE for the pre handlers. Also, with KPROBES_ON_FTRACE, the link register may be updated by the pre handlers or by a registed kretprobe. Honor updated LR by restoring it from pt_regs, rather than from the stack save area. Live patch and function graph continue to work fine with this change. Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 6432d4bf08c8..b846f75d7584 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1248,9 +1248,10 @@ _GLOBAL(ftrace_caller) /* Get the _mcount() call site out of LR */ mflr r7 - /* Save it as pt_regs->nip & pt_regs->link */ + /* Save it as pt_regs->nip */ std r7, _NIP(r1) - std r7, _LINK(r1) + /* Save the read LR in pt_regs->link */ + std r0, _LINK(r1) /* Save callee's TOC in the ABI compliant location */ std r2, 24(r1) @@ -1297,16 +1298,16 @@ ftrace_call: REST_8GPRS(16,r1) REST_8GPRS(24,r1) + /* Restore possibly modified LR */ + ld r0, _LINK(r1) + mtlr r0 + /* Restore callee's TOC */ ld r2, 24(r1) /* Pop our stack frame */ addi r1, r1, SWITCH_FRAME_SIZE - /* Restore original LR for return to B */ - ld r0, LRSAVE(r1) - mtlr r0 - #ifdef CONFIG_LIVEPATCH /* Based on the cmpd above, if the NIP was altered handle livepatch */ bne- livepatch_handler