Commit 0d423c4a authored by Alexey Romanov's avatar Alexey Romanov Committed by Neil Armstrong
Browse files

drivers: meson: sm: correct meson_sm_* API retval handling 



1. Following the ARM SMC32 calling convention, the return value
from secure monitor is a 32-bit signed integer. This patch changes
the type of the return value of the function meson_sm_call().

2. Now, when meson_sm_call() returns a 32-bit signed integer, we need
to ensure that this value is not negative. It is important to check
that the return value is not negative in both the meson_sm_call_read()
and meson_sm_call_write() functions.

3. Add a comment explaining why it is necessary to check if the SMC
return value is equal to 0 in the function meson_sm_call_read().
It is not obvious when reading this code.

Signed-off-by: default avatarAlexey Romanov <avromanov@salutedevices.com>
Reviewed-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230830140850.17130-1-avromanov@salutedevices.com


Signed-off-by: default avatarNeil Armstrong <neil.armstrong@linaro.org>
parent 0bb80ecc

drivers/firmware/meson/meson_sm.c

+13 −7
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ static u32 meson_sm_get_cmd(const struct meson_sm_chip *chip, 
	return cmd->smc_id;

}



static u32 __meson_sm_call(u32 cmd, u32 arg0, u32 arg1, u32 arg2,

static s32 __meson_sm_call(u32 cmd, u32 arg0, u32 arg1, u32 arg2,

			   u32 arg3, u32 arg4)

{

	struct arm_smccc_res res;
@@ -102,9 +102,10 @@ static void __iomem *meson_sm_map_shmem(u32 cmd_shmem, unsigned int size) 
 * Return:	0 on success, a negative value on error

 */

int meson_sm_call(struct meson_sm_firmware *fw, unsigned int cmd_index,

		  u32 *ret, u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)

		  s32 *ret, u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)

{

	u32 cmd, lret;

	u32 cmd;

	s32 lret;



	if (!fw->chip)

		return -ENOENT;
@@ -143,7 +144,7 @@ int meson_sm_call_read(struct meson_sm_firmware *fw, void *buffer, 
		       unsigned int bsize, unsigned int cmd_index, u32 arg0,

		       u32 arg1, u32 arg2, u32 arg3, u32 arg4)

{

	u32 size;

	s32 size;

	int ret;



	if (!fw->chip)
@@ -158,11 +159,16 @@ int meson_sm_call_read(struct meson_sm_firmware *fw, void *buffer, 
	if (meson_sm_call(fw, cmd_index, &size, arg0, arg1, arg2, arg3, arg4) < 0)

		return -EINVAL;



	if (size > bsize)

	if (size < 0 || size > bsize)

		return -EINVAL;



	ret = size;



	/* In some cases (for example GET_CHIP_ID command),

	 * SMC doesn't return the number of bytes read, even

	 * though the bytes were actually read into sm_shmem_out.

	 * So this check is needed.

	 */

	if (!size)

		size = bsize;
@@ -192,7 +198,7 @@ int meson_sm_call_write(struct meson_sm_firmware *fw, void *buffer, 
			unsigned int size, unsigned int cmd_index, u32 arg0,

			u32 arg1, u32 arg2, u32 arg3, u32 arg4)

{

	u32 written;

	s32 written;



	if (!fw->chip)

		return -ENOENT;
@@ -208,7 +214,7 @@ int meson_sm_call_write(struct meson_sm_firmware *fw, void *buffer, 
	if (meson_sm_call(fw, cmd_index, &written, arg0, arg1, arg2, arg3, arg4) < 0)

		return -EINVAL;



	if (!written)

	if (written <= 0 || written > size)

		return -EINVAL;



	return written;

include/linux/firmware/meson/meson_sm.h

+1 −1
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ enum { 
struct meson_sm_firmware;



int meson_sm_call(struct meson_sm_firmware *fw, unsigned int cmd_index,

		  u32 *ret, u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4);

		  s32 *ret, u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4);

int meson_sm_call_write(struct meson_sm_firmware *fw, void *buffer,

			unsigned int b_size, unsigned int cmd_index, u32 arg0,

			u32 arg1, u32 arg2, u32 arg3, u32 arg4);