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x86/unwind/orc: Detect the end of the stack

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The existing UNWIND_HINT_EMPTY annotations happen to be good indicators
of where entry code calls into C code for the first time.  So also use
them to mark the end of the stack for the ORC unwinder.

Use that information to set unwind->error if the ORC unwinder doesn't
unwind all the way to the end.  This will be needed for enabling
HAVE_RELIABLE_STACKTRACE for the ORC unwinder so we can use it with the
livepatch consistency model.

Thanks to Jiri Slaby for teaching the ORCs about the unwind hints.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/lkml/20180518064713.26440-5-jslaby@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf
2018-05-18 08:47:12 +02:00
committed by Ingo Molnar
parent 0c414367c0
commit d31a580266
9 changed files with 52 additions and 29 deletions
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52
arch/x86/kernel/unwind_orc.c
View File

@@ -198,7 +198,7 @@ static int orc_sort_cmp(const void *_a, const void *_b)
* whitelisted .o files which didn't get objtool generation.
*/
orc_a = cur_orc_table + (a - cur_orc_ip_table);
return orc_a->sp_reg == ORC_REG_UNDEFINED ? -1 : 1;
return orc_a->sp_reg == ORC_REG_UNDEFINED && !orc_a->end ? -1 : 1;
}
#ifdef CONFIG_MODULES
@@ -352,7 +352,7 @@ static bool deref_stack_iret_regs(struct unwind_state *state, unsigned long addr
bool unwind_next_frame(struct unwind_state *state)
{
unsigned long ip_p, sp, orig_ip, prev_sp = state->sp;
unsigned long ip_p, sp, orig_ip = state->ip, prev_sp = state->sp;
enum stack_type prev_type = state->stack_info.type;
struct orc_entry *orc;
bool indirect = false;
@@ -363,9 +363,9 @@ bool unwind_next_frame(struct unwind_state *state)
/* Don't let modules unload while we're reading their ORC data. */
preempt_disable();
/* Have we reached the end? */
/* End-of-stack check for user tasks: */
if (state->regs && user_mode(state->regs))
goto done;
goto the_end;
/*
* Find the orc_entry associated with the text address.
@@ -374,9 +374,16 @@ bool unwind_next_frame(struct unwind_state *state)
* calls and calls to noreturn functions.
*/
orc = orc_find(state->signal ? state->ip : state->ip - 1);
if (!orc || orc->sp_reg == ORC_REG_UNDEFINED)
goto done;
orig_ip = state->ip;
if (!orc)
goto err;
/* End-of-stack check for kernel threads: */
if (orc->sp_reg == ORC_REG_UNDEFINED) {
if (!orc->end)
goto err;
goto the_end;
}
/* Find the previous frame's stack: */
switch (orc->sp_reg) {
@@ -402,7 +409,7 @@ bool unwind_next_frame(struct unwind_state *state)
if (!state->regs || !state->full_regs) {
orc_warn("missing regs for base reg R10 at ip %pB\n",
(void *)state->ip);
goto done;
goto err;
}
sp = state->regs->r10;
break;
@@ -411,7 +418,7 @@ bool unwind_next_frame(struct unwind_state *state)
if (!state->regs || !state->full_regs) {
orc_warn("missing regs for base reg R13 at ip %pB\n",
(void *)state->ip);
goto done;
goto err;
}
sp = state->regs->r13;
break;
@@ -420,7 +427,7 @@ bool unwind_next_frame(struct unwind_state *state)
if (!state->regs || !state->full_regs) {
orc_warn("missing regs for base reg DI at ip %pB\n",
(void *)state->ip);
goto done;
goto err;
}
sp = state->regs->di;
break;
@@ -429,7 +436,7 @@ bool unwind_next_frame(struct unwind_state *state)
if (!state->regs || !state->full_regs) {
orc_warn("missing regs for base reg DX at ip %pB\n",
(void *)state->ip);
goto done;
goto err;
}
sp = state->regs->dx;
break;
@@ -437,12 +444,12 @@ bool unwind_next_frame(struct unwind_state *state)
default:
orc_warn("unknown SP base reg %d for ip %pB\n",
orc->sp_reg, (void *)state->ip);
goto done;
goto err;
}
if (indirect) {
if (!deref_stack_reg(state, sp, &sp))
goto done;
goto err;
}
/* Find IP, SP and possibly regs: */
@@ -451,7 +458,7 @@ bool unwind_next_frame(struct unwind_state *state)
ip_p = sp - sizeof(long);
if (!deref_stack_reg(state, ip_p, &state->ip))
goto done;
goto err;
state->ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
state->ip, (void *)ip_p);
@@ -465,7 +472,7 @@ bool unwind_next_frame(struct unwind_state *state)
if (!deref_stack_regs(state, sp, &state->ip, &state->sp)) {
orc_warn("can't dereference registers at %p for ip %pB\n",
(void *)sp, (void *)orig_ip);
goto done;
goto err;
}
state->regs = (struct pt_regs *)sp;
@@ -477,7 +484,7 @@ bool unwind_next_frame(struct unwind_state *state)
if (!deref_stack_iret_regs(state, sp, &state->ip, &state->sp)) {
orc_warn("can't dereference iret registers at %p for ip %pB\n",
(void *)sp, (void *)orig_ip);
goto done;
goto err;
}
state->regs = (void *)sp - IRET_FRAME_OFFSET;
@@ -500,18 +507,18 @@ bool unwind_next_frame(struct unwind_state *state)
case ORC_REG_PREV_SP:
if (!deref_stack_reg(state, sp + orc->bp_offset, &state->bp))
goto done;
goto err;
break;
case ORC_REG_BP:
if (!deref_stack_reg(state, state->bp + orc->bp_offset, &state->bp))
goto done;
goto err;
break;
default:
orc_warn("unknown BP base reg %d for ip %pB\n",
orc->bp_reg, (void *)orig_ip);
goto done;
goto err;
}
/* Prevent a recursive loop due to bad ORC data: */
@@ -520,13 +527,16 @@ bool unwind_next_frame(struct unwind_state *state)
state->sp <= prev_sp) {
orc_warn("stack going in the wrong direction? ip=%pB\n",
(void *)orig_ip);
goto done;
goto err;
}
preempt_enable();
return true;
done:
err:
state->error = true;
the_end:
preempt_enable();
state->stack_info.type = STACK_TYPE_UNKNOWN;
return false;