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| author | Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> | 2017-04-19 14:52:24 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-24 11:07:57 +0200 |
| commit | 2f59be5b970b503ca8db1cb723b155e455ebac8e (patch) | |
| tree | ad022579451aa590a33450abed9fd5d4426e7460 /arch/powerpc/kernel | |
| parent | powerpc/kprobes: Emulate instructions on kprobe handler re-entry (diff) | |
| download | linux-2f59be5b970b503ca8db1cb723b155e455ebac8e.tar.xz linux-2f59be5b970b503ca8db1cb723b155e455ebac8e.zip | |
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 <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 13 |
1 files changed, 7 insertions, 6 deletions
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 |