From fff184adc6e0622a9fa50ce9d6c7155e21898243 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Thu, 20 Feb 2020 16:05:17 -0800
Subject: drm/i915: Distribute switch variables for initialization
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Git-commit: 2713eb41a1a9149b330b80e03b2fbfa17c514c3f
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Variables declared in a switch statement before any case statements
cannot be automatically initialized with compiler instrumentation (as
they are not part of any execution flow). With GCC's proposed automatic
stack variable initialization feature, this triggers a warning (and they
don't get initialized). Clang's automatic stack variable initialization
(via CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also
doesn't initialize such variables[1]. Note that these warnings (or silent
skipping) happen before the dead-store elimination optimization phase,
so even when the automatic initializations are later elided in favor of
direct initializations, the warnings remain.
To avoid these problems, move such variables into the "case" where
they're used or lift them up into the main function body.
drivers/gpu/drm/i915/display/intel_display.c: In function ‘check_digital_port_conflicts’:
drivers/gpu/drm/i915/display/intel_display.c:12963:17: warning: statement will never be executed [-Wswitch-unreachable]
12963 | unsigned int port_mask;
| ^~~~~~~~~
drivers/gpu/drm/i915/intel_pm.c: In function ‘vlv_get_fifo_size’:
drivers/gpu/drm/i915/intel_pm.c:474:7: warning: statement will never be executed [-Wswitch-unreachable]
474 | u32 dsparb, dsparb2, dsparb3;
| ^~~~~~
drivers/gpu/drm/i915/intel_pm.c: In function ‘vlv_atomic_update_fifo’:
drivers/gpu/drm/i915/intel_pm.c:1997:7: warning: statement will never be executed [-Wswitch-unreachable]
1997 | u32 dsparb, dsparb2, dsparb3;
| ^~~~~~
[1] https://bugs.llvm.org/show_bug.cgi?id=44916
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/202002201602.92CADF7D@keescook
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/display/intel_display.c | 7 ++-----
drivers/gpu/drm/i915/intel_pm.c | 4 ++--
2 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index f950af561aca..0742cd478040 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -13155,7 +13155,6 @@ static bool check_digital_port_conflicts(struct intel_atomic_state *state)
WARN_ON(!connector_state->crtc);
switch (encoder->type) {
- unsigned int port_mask;
case INTEL_OUTPUT_DDI:
if (WARN_ON(!HAS_DDI(to_i915(dev))))
break;
@@ -13163,13 +13162,11 @@ static bool check_digital_port_conflicts(struct intel_atomic_state *state)
case INTEL_OUTPUT_DP:
case INTEL_OUTPUT_HDMI:
case INTEL_OUTPUT_EDP:
- port_mask = 1 << encoder->port;
-
/* the same port mustn't appear more than once */
- if (used_ports & port_mask)
+ if (used_ports & BIT(encoder->port))
ret = false;
- used_ports |= port_mask;
+ used_ports |= BIT(encoder->port);
break;
case INTEL_OUTPUT_DP_MST:
used_mst_ports |=
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 9b74c37e4fa4..22aa205793e5 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -469,9 +469,9 @@ static void vlv_get_fifo_size(struct intel_crtc_state *crtc_state)
struct vlv_fifo_state *fifo_state = &crtc_state->wm.vlv.fifo_state;
enum pipe pipe = crtc->pipe;
int sprite0_start, sprite1_start;
+ u32 dsparb, dsparb2, dsparb3;
switch (pipe) {
- u32 dsparb, dsparb2, dsparb3;
case PIPE_A:
dsparb = I915_READ(DSPARB);
dsparb2 = I915_READ(DSPARB2);
@@ -1969,6 +1969,7 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state,
const struct vlv_fifo_state *fifo_state =
&crtc_state->wm.vlv.fifo_state;
int sprite0_start, sprite1_start, fifo_size;
+ u32 dsparb, dsparb2, dsparb3;
if (!crtc_state->fifo_changed)
return;
@@ -1994,7 +1995,6 @@ static void vlv_atomic_update_fifo(struct intel_atomic_state *state,
spin_lock(&uncore->lock);
switch (crtc->pipe) {
- u32 dsparb, dsparb2, dsparb3;
case PIPE_A:
dsparb = intel_uncore_read_fw(uncore, DSPARB);
dsparb2 = intel_uncore_read_fw(uncore, DSPARB2);
--
2.28.0