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Message-Id: <20191106095601.29986-3-mbenes@suse.cz>
Date: Wed, 6 Nov 2019 10:55:59 +0100
From: Miroslav Benes <mbenes@...e.cz>
To: heiko.carstens@...ibm.com, gor@...ux.ibm.com,
borntraeger@...ibm.com, jpoimboe@...hat.com,
joe.lawrence@...hat.com
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
jikos@...nel.org, pmladek@...e.com, nstange@...e.de,
live-patching@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH v3 2/4] s390/unwind: split unwind_next_frame() to several functions
Function unwind_next_frame() becomes less readable with each new
change. Split it to several functions to amend it and prepare for new
additions.
No functional change.
Suggested-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Miroslav Benes <mbenes@...e.cz>
---
arch/s390/kernel/unwind_bc.c | 136 ++++++++++++++++++++++-------------
1 file changed, 88 insertions(+), 48 deletions(-)
diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index 5a78deacb972..96da99ec7b59 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -36,55 +36,10 @@ static bool update_stack_info(struct unwind_state *state, unsigned long sp)
return true;
}
-bool unwind_next_frame(struct unwind_state *state)
+static bool unwind_update_state(struct unwind_state *state,
+ unsigned long sp, unsigned long ip,
+ struct pt_regs *regs, bool reliable)
{
- struct stack_info *info = &state->stack_info;
- struct stack_frame *sf;
- struct pt_regs *regs;
- unsigned long sp, ip;
- bool reliable;
-
- regs = state->regs;
- if (unlikely(regs)) {
- if (state->reuse_sp) {
- sp = state->sp;
- state->reuse_sp = false;
- } else {
- sp = READ_ONCE_NOCHECK(regs->gprs[15]);
- if (unlikely(outside_of_stack(state, sp))) {
- if (!update_stack_info(state, sp))
- goto out_err;
- }
- }
- sf = (struct stack_frame *) sp;
- ip = READ_ONCE_NOCHECK(sf->gprs[8]);
- reliable = false;
- regs = NULL;
- } else {
- sf = (struct stack_frame *) state->sp;
- sp = READ_ONCE_NOCHECK(sf->back_chain);
- if (likely(sp)) {
- /* Non-zero back-chain points to the previous frame */
- if (unlikely(outside_of_stack(state, sp))) {
- if (!update_stack_info(state, sp))
- goto out_err;
- }
- sf = (struct stack_frame *) sp;
- ip = READ_ONCE_NOCHECK(sf->gprs[8]);
- reliable = true;
- } else {
- /* No back-chain, look for a pt_regs structure */
- sp = state->sp + STACK_FRAME_OVERHEAD;
- if (!on_stack(info, sp, sizeof(struct pt_regs)))
- goto out_stop;
- regs = (struct pt_regs *) sp;
- if (READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE)
- goto out_stop;
- ip = READ_ONCE_NOCHECK(regs->psw.addr);
- reliable = true;
- }
- }
-
ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
ip, (void *) sp);
@@ -94,13 +49,98 @@ bool unwind_next_frame(struct unwind_state *state)
state->regs = regs;
state->reliable = reliable;
return true;
+}
+
+static bool unwind_use_regs(struct unwind_state *state)
+{
+ struct stack_frame *sf;
+ unsigned long sp, ip;
+ struct pt_regs *regs = state->regs;
+
+ if (state->reuse_sp) {
+ sp = state->sp;
+ state->reuse_sp = false;
+ } else {
+ sp = READ_ONCE_NOCHECK(regs->gprs[15]);
+ if (unlikely(outside_of_stack(state, sp))) {
+ if (!update_stack_info(state, sp))
+ goto out_err;
+ }
+ }
+
+ sf = (struct stack_frame *) sp;
+ ip = READ_ONCE_NOCHECK(sf->gprs[8]);
+
+ return unwind_update_state(state, sp, ip, NULL, false);
+
+out_err:
+ state->error = true;
+ state->stack_info.type = STACK_TYPE_UNKNOWN;
+ return false;
+}
+
+static bool unwind_use_frame(struct unwind_state *state, unsigned long sp)
+{
+ struct stack_frame *sf;
+ unsigned long ip;
+
+ if (unlikely(outside_of_stack(state, sp))) {
+ if (!update_stack_info(state, sp))
+ goto out_err;
+ }
+
+ sf = (struct stack_frame *) sp;
+ ip = READ_ONCE_NOCHECK(sf->gprs[8]);
+
+ return unwind_update_state(state, sp, ip, NULL, true);
out_err:
state->error = true;
+ state->stack_info.type = STACK_TYPE_UNKNOWN;
+ return false;
+}
+
+static bool unwind_look_for_regs(struct unwind_state *state)
+{
+ struct stack_info *info = &state->stack_info;
+ struct pt_regs *regs;
+ unsigned long sp, ip;
+
+ sp = state->sp + STACK_FRAME_OVERHEAD;
+ if (!on_stack(info, sp, sizeof(struct pt_regs)))
+ goto out_stop;
+
+ regs = (struct pt_regs *) sp;
+ if (READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE)
+ goto out_stop;
+
+ ip = READ_ONCE_NOCHECK(regs->psw.addr);
+
+ return unwind_update_state(state, sp, ip, regs, true);
+
out_stop:
state->stack_info.type = STACK_TYPE_UNKNOWN;
return false;
}
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+ struct stack_frame *sf;
+ unsigned long sp;
+
+ if (unlikely(state->regs))
+ return unwind_use_regs(state);
+
+ sf = (struct stack_frame *) state->sp;
+ sp = READ_ONCE_NOCHECK(sf->back_chain);
+
+ /* Non-zero back-chain points to the previous frame */
+ if (likely(sp))
+ return unwind_use_frame(state, sp);
+
+ /* No back-chain, look for a pt_regs structure */
+ return unwind_look_for_regs(state);
+}
EXPORT_SYMBOL_GPL(unwind_next_frame);
void __unwind_start(struct unwind_state *state, struct task_struct *task,
--
2.23.0
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