[PATCH 2/2] clk: bcm2835: Remove casting to bcm2835_clk_register

From: Nathan Chancellor
Date: Sat May 16 2020 - 04:08:25 EST

There are four different callback functions that are used for the
clk_register callback that all have different second parameter types.

bcm2835_register_pll -> struct bcm2835_pll_data
bcm2835_register_pll_divider -> struct bcm2835_pll_divider_data
bcm2835_register_clock -> struct bcm2835_clock_data
bcm2835_register_date -> struct bcm2835_gate_data

These callbacks are cast to bcm2835_clk_register so that there is no
error about incompatible pointer types. Unfortunately, this is a control
flow integrity violation, which verifies that the callback function's
types match the prototypes exactly before jumping.

[ 0.857913] CFI failure (target: 0xffffff9334a81820):
[ 0.857977] WARNING: CPU: 3 PID: 35 at kernel/cfi.c:29 __cfi_check_fail+0x50/0x58
[ 0.857985] Modules linked in:
[ 0.858007] CPU: 3 PID: 35 Comm: kworker/3:1 Not tainted 4.19.123-v8-01301-gdbb48f16956e4-dirty #1
[ 0.858015] Hardware name: Raspberry Pi 3 Model B Rev 1.2 (DT)
[ 0.858031] Workqueue: events 0xffffff9334a925c8
[ 0.858046] pstate: 60000005 (nZCv daif -PAN -UAO)
[ 0.858058] pc : __cfi_check_fail+0x50/0x58
[ 0.858070] lr : __cfi_check_fail+0x50/0x58
[ 0.858078] sp : ffffff800814ba90
[ 0.858086] x29: ffffff800814ba90 x28: 000fffffffdfff3d
[ 0.858101] x27: 00000000002000c2 x26: ffffff93355fdb18
[ 0.858116] x25: 0000000000000000 x24: ffffff9334a81820
[ 0.858131] x23: ffffff93357f3580 x22: ffffff9334af1000
[ 0.858146] x21: a79b57e88f8ebc81 x20: ffffff93357f3580
[ 0.858161] x19: ffffff9334a81820 x18: fffffff679769070
[ 0.858175] x17: 0000000000000000 x16: 0000000000000000
[ 0.858190] x15: 0000000000000004 x14: 000000000000003c
[ 0.858205] x13: 0000000000003044 x12: 0000000000000000
[ 0.858220] x11: b57e91cd641bae00 x10: b57e91cd641bae00
[ 0.858235] x9 : b57e91cd641bae00 x8 : b57e91cd641bae00
[ 0.858250] x7 : 0000000000000000 x6 : ffffff933591d4e5
[ 0.858264] x5 : 0000000000000000 x4 : 0000000000000000
[ 0.858279] x3 : ffffff800814b718 x2 : ffffff9334a84818
[ 0.858293] x1 : ffffff9334bba66c x0 : 0000000000000029
[ 0.858308] Call trace:
[ 0.858321] __cfi_check_fail+0x50/0x58
[ 0.858337] __cfi_check+0x3ab3c/0x4467c
[ 0.858351] bcm2835_clk_probe+0x210/0x2dc
[ 0.858369] platform_drv_probe+0xb0/0xfc
[ 0.858380] really_probe+0x4a0/0x5a8
[ 0.858391] driver_probe_device+0x68/0x104
[ 0.858403] __device_attach_driver+0x100/0x148
[ 0.858418] bus_for_each_drv+0xb0/0x12c
[ 0.858431] __device_attach.llvm.17225159516306086099+0xc0/0x168
[ 0.858443] bus_probe_device+0x44/0xfc
[ 0.858455] deferred_probe_work_func+0xa0/0xe0
[ 0.858472] process_one_work+0x210/0x538
[ 0.858485] worker_thread+0x2e8/0x478
[ 0.858500] kthread+0x154/0x164
[ 0.858515] ret_from_fork+0x10/0x18

To fix this, change the second parameter of all functions void * and use
a local variable with the correct type so that everything works
properly. With this, the only use of bcm2835_clk_register is in struct
bcm2835_clk_desc so we can just remove it and use the type directly.

Fixes: 56eb3a2ed972 ("clk: bcm2835: remove use of BCM2835_CLOCK_COUNT in driver")
Link: https://github.com/ClangBuiltLinux/linux/issues/1028
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
---
drivers/clk/bcm/clk-bcm2835.c | 68 +++++++++++++++++++----------------
1 file changed, 37 insertions(+), 31 deletions(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 7c845c293af0..0d0eeb3b0dd5 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1296,8 +1296,9 @@ static const struct clk_ops bcm2835_vpu_clock_clk_ops = {
};

static struct clk_hw *bcm2835_register_pll(struct bcm2835_cprman *cprman,
- const struct bcm2835_pll_data *data)
+ const void *data)
{
+ const struct bcm2835_pll_data *pll_data = data;
struct bcm2835_pll *pll;
struct clk_init_data init;
int ret;
@@ -1307,7 +1308,7 @@ static struct clk_hw *bcm2835_register_pll(struct bcm2835_cprman *cprman,
/* All of the PLLs derive from the external oscillator. */
init.parent_names = &cprman->real_parent_names[0];
init.num_parents = 1;
- init.name = data->name;
+ init.name = pll_data->name;
init.ops = &bcm2835_pll_clk_ops;
init.flags = CLK_IGNORE_UNUSED;

@@ -1316,7 +1317,7 @@ static struct clk_hw *bcm2835_register_pll(struct bcm2835_cprman *cprman,
return NULL;

pll->cprman = cprman;
- pll->data = data;
+ pll->data = pll_data;
pll->hw.init = &init;

ret = devm_clk_hw_register(cprman->dev, &pll->hw);
@@ -1327,35 +1328,36 @@ static struct clk_hw *bcm2835_register_pll(struct bcm2835_cprman *cprman,

static struct clk_hw *
bcm2835_register_pll_divider(struct bcm2835_cprman *cprman,
- const struct bcm2835_pll_divider_data *data)
+ const void *data)
{
+ const struct bcm2835_pll_divider_data *divider_data = data;
struct bcm2835_pll_divider *divider;
struct clk_init_data init;
const char *divider_name;
int ret;

- if (data->fixed_divider != 1) {
+ if (divider_data->fixed_divider != 1) {
divider_name = devm_kasprintf(cprman->dev, GFP_KERNEL,
- "%s_prediv", data->name);
+ "%s_prediv", divider_data->name);
if (!divider_name)
return NULL;
} else {
- divider_name = data->name;
+ divider_name = divider_data->name;
}

memset(&init, 0, sizeof(init));

- init.parent_names = &data->source_pll;
+ init.parent_names = &divider_data->source_pll;
init.num_parents = 1;
init.name = divider_name;
init.ops = &bcm2835_pll_divider_clk_ops;
- init.flags = data->flags | CLK_IGNORE_UNUSED;
+ init.flags = divider_data->flags | CLK_IGNORE_UNUSED;

divider = devm_kzalloc(cprman->dev, sizeof(*divider), GFP_KERNEL);
if (!divider)
return NULL;

- divider->div.reg = cprman->regs + data->a2w_reg;
+ divider->div.reg = cprman->regs + divider_data->a2w_reg;
divider->div.shift = A2W_PLL_DIV_SHIFT;
divider->div.width = A2W_PLL_DIV_BITS;
divider->div.flags = CLK_DIVIDER_MAX_AT_ZERO;
@@ -1364,7 +1366,7 @@ bcm2835_register_pll_divider(struct bcm2835_cprman *cprman,
divider->div.table = NULL;

divider->cprman = cprman;
- divider->data = data;
+ divider->data = divider_data;

ret = devm_clk_hw_register(cprman->dev, &divider->div.hw);
if (ret)
@@ -1374,20 +1376,22 @@ bcm2835_register_pll_divider(struct bcm2835_cprman *cprman,
* PLLH's channels have a fixed divide by 10 afterwards, which
* is what our consumers are actually using.
*/
- if (data->fixed_divider != 1) {
- return clk_hw_register_fixed_factor(cprman->dev, data->name,
+ if (divider_data->fixed_divider != 1) {
+ return clk_hw_register_fixed_factor(cprman->dev,
+ divider_data->name,
divider_name,
CLK_SET_RATE_PARENT,
1,
- data->fixed_divider);
+ divider_data->fixed_divider);
}

return &divider->div.hw;
}

static struct clk_hw *bcm2835_register_clock(struct bcm2835_cprman *cprman,
- const struct bcm2835_clock_data *data)
+ const void *data)
{
+ const struct bcm2835_clock_data *clock_data = data;
struct bcm2835_clock *clock;
struct clk_init_data init;
const char *parents[1 << CM_SRC_BITS];
@@ -1398,8 +1402,8 @@ static struct clk_hw *bcm2835_register_clock(struct bcm2835_cprman *cprman,
* Replace our strings referencing parent clocks with the
* actual clock-output-name of the parent.
*/
- for (i = 0; i < data->num_mux_parents; i++) {
- parents[i] = data->parents[i];
+ for (i = 0; i < clock_data->num_mux_parents; i++) {
+ parents[i] = clock_data->parents[i];

ret = match_string(cprman_parent_names,
ARRAY_SIZE(cprman_parent_names),
@@ -1410,18 +1414,18 @@ static struct clk_hw *bcm2835_register_clock(struct bcm2835_cprman *cprman,

memset(&init, 0, sizeof(init));
init.parent_names = parents;
- init.num_parents = data->num_mux_parents;
- init.name = data->name;
- init.flags = data->flags | CLK_IGNORE_UNUSED;
+ init.num_parents = clock_data->num_mux_parents;
+ init.name = clock_data->name;
+ init.flags = clock_data->flags | CLK_IGNORE_UNUSED;

/*
* Pass the CLK_SET_RATE_PARENT flag if we are allowed to propagate
* rate changes on at least of the parents.
*/
- if (data->set_rate_parent)
+ if (clock_data->set_rate_parent)
init.flags |= CLK_SET_RATE_PARENT;

- if (data->is_vpu_clock) {
+ if (clock_data->is_vpu_clock) {
init.ops = &bcm2835_vpu_clock_clk_ops;
} else {
init.ops = &bcm2835_clock_clk_ops;
@@ -1430,7 +1434,7 @@ static struct clk_hw *bcm2835_register_clock(struct bcm2835_cprman *cprman,
/* If the clock wasn't actually enabled at boot, it's not
* critical.
*/
- if (!(cprman_read(cprman, data->ctl_reg) & CM_ENABLE))
+ if (!(cprman_read(cprman, clock_data->ctl_reg) & CM_ENABLE))
init.flags &= ~CLK_IS_CRITICAL;
}

@@ -1439,7 +1443,7 @@ static struct clk_hw *bcm2835_register_clock(struct bcm2835_cprman *cprman,
return NULL;

clock->cprman = cprman;
- clock->data = data;
+ clock->data = clock_data;
clock->hw.init = &init;

ret = devm_clk_hw_register(cprman->dev, &clock->hw);
@@ -1449,24 +1453,26 @@ static struct clk_hw *bcm2835_register_clock(struct bcm2835_cprman *cprman,
}

static struct clk_hw *bcm2835_register_gate(struct bcm2835_cprman *cprman,
- const struct bcm2835_gate_data *data)
+ const void *data)
{
- return clk_hw_register_gate(cprman->dev, data->name, data->parent,
+ const struct bcm2835_gate_data *gate_data = data;
+
+ return clk_hw_register_gate(cprman->dev, gate_data->name,
+ gate_data->parent,
CLK_IGNORE_UNUSED | CLK_SET_RATE_GATE,
- cprman->regs + data->ctl_reg,
+ cprman->regs + gate_data->ctl_reg,
CM_GATE_BIT, 0, &cprman->regs_lock);
}

-typedef struct clk_hw *(*bcm2835_clk_register)(struct bcm2835_cprman *cprman,
- const void *data);
struct bcm2835_clk_desc {
- bcm2835_clk_register clk_register;
+ struct clk_hw *(*clk_register)(struct bcm2835_cprman *cprman,
+ const void *data);
unsigned int supported;
const void *data;
};

/* assignment helper macros for different clock types */
-#define _REGISTER(f, s, ...) { .clk_register = (bcm2835_clk_register)f, \
+#define _REGISTER(f, s, ...) { .clk_register = f, \
.supported = s, \
.data = __VA_ARGS__ }
#define REGISTER_PLL(s, ...) _REGISTER(&bcm2835_register_pll, \
--
2.26.2