On Fri, 2021-11-05 at 11:03 +0200, Kalle Valo wrote: > Takashi Iwai <tiwai@xxxxxxx> writes: > > > On Fri, 05 Nov 2021 09:25:13 +0100, > > Kalle Valo wrote: > > > Takashi Iwai <tiwai@xxxxxxx> writes: > > > > > > > On Fri, 05 Nov 2021 08:17:25 +0100, > > > > Takashi Iwai wrote: > > > > > When a firmware is loaded in the compressed format or via user-mode > > > > > helper, it's mapped in read-only, and the rtw89 driver crashes at > > > > > rtw89_fw_download() when it tries to modify some data. > > > > > > > > > > This patch is an attemp to avoid the crash by re-allocating the data > > > > > via vmalloc() for the data modification. > > > > > > > > Alternatively, we may drop the code that modifies the loaded firmware > > > > data? At least SET_FW_HDR_PART_SIZE() in rtw89_fw_hdr_parser() looks > > > > writing it, and I have no idea why this overwrite is needed. > > > > > > Strange, isn't the firmware data marked as const just to avoid this kind > > > of problem? Does rtw89 have wrong casts somewhere which removes the > > > const? > > > > Yes. SET_FW_HDR_PART_SIZE() does the cast, dropping the const. > > Oh man, all of GET and SET macros in fw.h have those casts: > > #define GET_FW_HDR_MAJOR_VERSION(fwhdr) \ > le32_get_bits(*((__le32 *)(fwhdr) + 1), GENMASK(7, 0)) > #define GET_FW_HDR_MINOR_VERSION(fwhdr) \ > le32_get_bits(*((__le32 *)(fwhdr) + 1), GENMASK(15, 8)) > #define GET_FW_HDR_SUBVERSION(fwhdr) \ > le32_get_bits(*((__le32 *)(fwhdr) + 1), GENMASK(23, 16)) > > I don't know how I missed those during my review :( But this is exactly > why I prefer having a proper struct for commands and events, instead of > u8 buf used with these macros. > I can use a struct to access firmware header, becuase their fields are multiple of 8 bits. But, the "firmware section header" that is additional header followed by firmware header, and it contains bit fields, likes: #define GET_FWSECTION_HDR_SEC_SIZE(fwhdr) \ le32_get_bits(*((__le32 *)(fwhdr) + 1), GENMASK(23, 0)) #define GET_FWSECTION_HDR_CHECKSUM(fwhdr) \ le32_get_bits(*((__le32 *)(fwhdr) + 1), BIT(28)) #define GET_FWSECTION_HDR_REDL(fwhdr) \ le32_get_bits(*((__le32 *)(fwhdr) + 1), BIT(29)) #define GET_FWSECTION_HDR_DL_ADDR(fwhdr) \ le32_get_bits(*((__le32 *)(fwhdr)), GENMASK(31, 0)) If we use a struct, it needs big-/little- endians parts. Then, we will access firmware header with two methods; is it reasonable? The macro SET_FW_HDR_PART_SIZE() is used to set the firmware partition size we are going to download, and it is only used by rtw89_fw_download_hdr(). So, I will set the partition size after copying constant firmware header into skb->data. -- Ping-Ke
