ACPI: sysfs: copy ACPI data using io memory copying
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Message ID 20200312111345.1057569-1-colin.king@canonical.com
State In Next
Commit 08c07cefb3042a55bc9f8243814b504d5eff93f3
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Series
  • ACPI: sysfs: copy ACPI data using io memory copying
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Commit Message

Colin Ian King March 12, 2020, 11:13 a.m. UTC
From: Colin Ian King <colin.king@canonical.com>

Reading ACPI data on ARM64 at a non-aligned offset from
/sys/firmware/acpi/tables/data/BERT will cause a splat because
the data is I/O memory mapped and being read with just a memcpy.
Fix this by introducing an I/O variant of memory_read_from_buffer
and using I/O memory mapped copies instead.

Fixes the following splat:

[  439.789355] Unable to handle kernel paging request at virtual address ffff800041ac0007
[  439.797275] Mem abort info:
[  439.800078]   ESR = 0x96000021
[  439.803131]   EC = 0x25: DABT (current EL), IL = 32 bits
[  439.808437]   SET = 0, FnV = 0
[  439.811486]   EA = 0, S1PTW = 0
[  439.814621] Data abort info:
[  439.817489]   ISV = 0, ISS = 0x00000021
[  439.821319]   CM = 0, WnR = 0
[  439.824282] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000817fc000
[  439.830979] [ffff800041ac0007] pgd=000000bffcfff003, pud=0000009f27cee003, pmd=000000bf4b993003, pte=0068000080280703
[  439.841584] Internal error: Oops: 96000021 [#1] SMP
[  439.846449] Modules linked in: nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua ipmi_ssif input_leds joydev ipmi_devintf ipmi_msghandler thunderx2_pmu sch_fq_codel ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq libcrc32c raid1 raid0 multipath linear i2c_smbus ast i2c_algo_bit crct10dif_ce drm_vram_helper uas ttm ghash_ce drm_kms_helper sha2_ce syscopyarea sha256_arm64 qede sysfillrect mpt3sas sha1_ce sysimgblt fb_sys_fops raid_class qed drm scsi_transport_sas usb_storage ahci crc8 gpio_xlp i2c_xlp9xx hid_generic usbhid hid aes_neon_bs aes_neon_blk aes_ce_blk crypto_simd cryptd aes_ce_cipher
[  439.908474] CPU: 2 PID: 3926 Comm: a.out Not tainted 5.4.0-14-generic #17-Ubuntu
[  439.915855] Hardware name: To be filled by O.E.M. Saber/Saber, BIOS 0ACKL027 07/01/2019
[  439.923844] pstate: 80400009 (Nzcv daif +PAN -UAO)
[  439.928625] pc : __memcpy+0x90/0x180
[  439.932192] lr : memory_read_from_buffer+0x64/0x88
[  439.936968] sp : ffff8000350dbc70
[  439.940270] x29: ffff8000350dbc70 x28: ffff009e9c444b00
[  439.945568] x27: 0000000000000000 x26: 0000000000000000
[  439.950866] x25: 0000000056000000 x24: ffff800041ac0000
[  439.956164] x23: ffff009ea163f980 x22: 0000000000000007
[  439.961462] x21: ffff8000350dbce8 x20: 000000000000000e
[  439.966760] x19: 0000000000000007 x18: ffff8000112f64a8
[  439.972058] x17: 0000000000000000 x16: 0000000000000000
[  439.977355] x15: 0000000080280000 x14: ffff800041aed000
[  439.982653] x13: ffff009ee9fa2840 x12: ffff800041ad1000
[  439.987951] x11: ffff8000115e1360 x10: ffff8000115e1360
[  439.993248] x9 : 0000000000010000 x8 : ffff800011ad2658
[  439.998546] x7 : ffff800041ac0000 x6 : ffff009ea163f980
[  440.003844] x5 : 0140000000000000 x4 : 0000000000010000
[  440.009141] x3 : ffff800041ac0000 x2 : 0000000000000007
[  440.014439] x1 : ffff800041ac0007 x0 : ffff009ea163f980
[  440.019737] Call trace:
[  440.022173]  __memcpy+0x90/0x180
[  440.025392]  acpi_data_show+0x54/0x80
[  440.029044]  sysfs_kf_bin_read+0x6c/0xa8
[  440.032954]  kernfs_file_direct_read+0x90/0x2d0
[  440.037470]  kernfs_fop_read+0x68/0x78
[  440.041210]  __vfs_read+0x48/0x90
[  440.044511]  vfs_read+0xd0/0x1a0
[  440.047726]  ksys_read+0x78/0x100
[  440.051028]  __arm64_sys_read+0x24/0x30
[  440.054852]  el0_svc_common.constprop.0+0xdc/0x1d8
[  440.059629]  el0_svc_handler+0x34/0xa0
[  440.063366]  el0_svc+0x10/0x14
[  440.066411] Code: 36180062 f8408423 f80084c3 36100062 (b8404423)
[  440.072492] ---[ end trace 45fb374e8d2d800e ]---

A simple reproducer is as follows:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>

int main(void)
{
        int fd;
        char buffer[7];
        ssize_t n;

        fd = open("/sys/firmware/acpi/tables/data/BERT", O_RDONLY);
        if (fd < 0) {
                perror("open failed");
                return -1;
        }
        do {
                n = read(fd, buffer, sizeof(buffer));
        } while (n > 0);

        return 0;
}

BugLink: https://bugs.launchpad.net/bugs/1866772
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/acpi/sysfs.c   |  2 +-
 fs/libfs.c             | 33 +++++++++++++++++++++++++++++++++
 include/linux/string.h |  2 ++
 3 files changed, 36 insertions(+), 1 deletion(-)

Comments

Rafael J. Wysocki March 14, 2020, 10:23 a.m. UTC | #1
On Thursday, March 12, 2020 12:13:45 PM CET Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Reading ACPI data on ARM64 at a non-aligned offset from
> /sys/firmware/acpi/tables/data/BERT will cause a splat because
> the data is I/O memory mapped and being read with just a memcpy.
> Fix this by introducing an I/O variant of memory_read_from_buffer
> and using I/O memory mapped copies instead.
> 
> Fixes the following splat:
> 
> [  439.789355] Unable to handle kernel paging request at virtual address ffff800041ac0007
> [  439.797275] Mem abort info:
> [  439.800078]   ESR = 0x96000021
> [  439.803131]   EC = 0x25: DABT (current EL), IL = 32 bits
> [  439.808437]   SET = 0, FnV = 0
> [  439.811486]   EA = 0, S1PTW = 0
> [  439.814621] Data abort info:
> [  439.817489]   ISV = 0, ISS = 0x00000021
> [  439.821319]   CM = 0, WnR = 0
> [  439.824282] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000817fc000
> [  439.830979] [ffff800041ac0007] pgd=000000bffcfff003, pud=0000009f27cee003, pmd=000000bf4b993003, pte=0068000080280703
> [  439.841584] Internal error: Oops: 96000021 [#1] SMP
> [  439.846449] Modules linked in: nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua ipmi_ssif input_leds joydev ipmi_devintf ipmi_msghandler thunderx2_pmu sch_fq_codel ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq libcrc32c raid1 raid0 multipath linear i2c_smbus ast i2c_algo_bit crct10dif_ce drm_vram_helper uas ttm ghash_ce drm_kms_helper sha2_ce syscopyarea sha256_arm64 qede sysfillrect mpt3sas sha1_ce sysimgblt fb_sys_fops raid_class qed drm scsi_transport_sas usb_storage ahci crc8 gpio_xlp i2c_xlp9xx hid_generic usbhid hid aes_neon_bs aes_neon_blk aes_ce_blk crypto_simd cryptd aes_ce_cipher
> [  439.908474] CPU: 2 PID: 3926 Comm: a.out Not tainted 5.4.0-14-generic #17-Ubuntu
> [  439.915855] Hardware name: To be filled by O.E.M. Saber/Saber, BIOS 0ACKL027 07/01/2019
> [  439.923844] pstate: 80400009 (Nzcv daif +PAN -UAO)
> [  439.928625] pc : __memcpy+0x90/0x180
> [  439.932192] lr : memory_read_from_buffer+0x64/0x88
> [  439.936968] sp : ffff8000350dbc70
> [  439.940270] x29: ffff8000350dbc70 x28: ffff009e9c444b00
> [  439.945568] x27: 0000000000000000 x26: 0000000000000000
> [  439.950866] x25: 0000000056000000 x24: ffff800041ac0000
> [  439.956164] x23: ffff009ea163f980 x22: 0000000000000007
> [  439.961462] x21: ffff8000350dbce8 x20: 000000000000000e
> [  439.966760] x19: 0000000000000007 x18: ffff8000112f64a8
> [  439.972058] x17: 0000000000000000 x16: 0000000000000000
> [  439.977355] x15: 0000000080280000 x14: ffff800041aed000
> [  439.982653] x13: ffff009ee9fa2840 x12: ffff800041ad1000
> [  439.987951] x11: ffff8000115e1360 x10: ffff8000115e1360
> [  439.993248] x9 : 0000000000010000 x8 : ffff800011ad2658
> [  439.998546] x7 : ffff800041ac0000 x6 : ffff009ea163f980
> [  440.003844] x5 : 0140000000000000 x4 : 0000000000010000
> [  440.009141] x3 : ffff800041ac0000 x2 : 0000000000000007
> [  440.014439] x1 : ffff800041ac0007 x0 : ffff009ea163f980
> [  440.019737] Call trace:
> [  440.022173]  __memcpy+0x90/0x180
> [  440.025392]  acpi_data_show+0x54/0x80
> [  440.029044]  sysfs_kf_bin_read+0x6c/0xa8
> [  440.032954]  kernfs_file_direct_read+0x90/0x2d0
> [  440.037470]  kernfs_fop_read+0x68/0x78
> [  440.041210]  __vfs_read+0x48/0x90
> [  440.044511]  vfs_read+0xd0/0x1a0
> [  440.047726]  ksys_read+0x78/0x100
> [  440.051028]  __arm64_sys_read+0x24/0x30
> [  440.054852]  el0_svc_common.constprop.0+0xdc/0x1d8
> [  440.059629]  el0_svc_handler+0x34/0xa0
> [  440.063366]  el0_svc+0x10/0x14
> [  440.066411] Code: 36180062 f8408423 f80084c3 36100062 (b8404423)
> [  440.072492] ---[ end trace 45fb374e8d2d800e ]---
> 
> A simple reproducer is as follows:
> 
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <unistd.h>
> #include <stdio.h>
> #include <string.h>
> 
> int main(void)
> {
>         int fd;
>         char buffer[7];
>         ssize_t n;
> 
>         fd = open("/sys/firmware/acpi/tables/data/BERT", O_RDONLY);
>         if (fd < 0) {
>                 perror("open failed");
>                 return -1;
>         }
>         do {
>                 n = read(fd, buffer, sizeof(buffer));
>         } while (n > 0);
> 
>         return 0;
> }
> 
> BugLink: https://bugs.launchpad.net/bugs/1866772
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/acpi/sysfs.c   |  2 +-
>  fs/libfs.c             | 33 +++++++++++++++++++++++++++++++++
>  include/linux/string.h |  2 ++
>  3 files changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
> index c60d2c6d31d6..fb9e216cb8c0 100644
> --- a/drivers/acpi/sysfs.c
> +++ b/drivers/acpi/sysfs.c
> @@ -446,7 +446,7 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
>  	base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
>  	if (!base)
>  		return -ENOMEM;
> -	rc = memory_read_from_buffer(buf, count, &offset, base,
> +	rc = memory_read_from_io_buffer(buf, count, &offset, base,
>  				     data_attr->attr.size);
>  	acpi_os_unmap_memory(base, data_attr->attr.size);
>  
> diff --git a/fs/libfs.c b/fs/libfs.c
> index c686bd9caac6..3e112c51ce7b 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -800,6 +800,39 @@ ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
>  }
>  EXPORT_SYMBOL(memory_read_from_buffer);
>  
> +/**
> + * memory_read_from_io_buffer - copy data from a io memory mapped buffer
> + * @to: the kernel space buffer to read to
> + * @count: the maximum number of bytes to read
> + * @ppos: the current position in the buffer
> + * @from: the buffer to read from
> + * @available: the size of the buffer
> + *
> + * The memory_read_from_buffer() function reads up to @count bytes from the
> + * io memory mappy buffer @from at offset @ppos into the kernel space address
> + * starting at @to.
> + *
> + * On success, the number of bytes read is returned and the offset @ppos is
> + * advanced by this number, or negative value is returned on error.
> + **/
> +ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
> +				   const void *from, size_t available)
> +{
> +	loff_t pos = *ppos;
> +
> +	if (pos < 0)
> +		return -EINVAL;
> +	if (pos >= available)
> +		return 0;
> +	if (count > available - pos)
> +		count = available - pos;
> +	memcpy_fromio(to, from + pos, count);
> +	*ppos = pos + count;
> +
> +	return count;
> +}
> +EXPORT_SYMBOL(memory_read_from_io_buffer);
> +
>  /*
>   * Transaction based IO.
>   * The file expects a single write which triggers the transaction, and then
> diff --git a/include/linux/string.h b/include/linux/string.h
> index 6dfbb2efa815..0c6ec2aa3909 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -216,6 +216,8 @@ int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
>  
>  extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
>  				       const void *from, size_t available);
> +extern ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
> +					  const void *from, size_t available);
>  
>  int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);
>  
> 

Applied as 5.7 material, thanks!
Colin Ian King Sept. 2, 2020, 10:27 a.m. UTC | #2
On 14/03/2020 10:23, Rafael J. Wysocki wrote:
> On Thursday, March 12, 2020 12:13:45 PM CET Colin King wrote:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Reading ACPI data on ARM64 at a non-aligned offset from
>> /sys/firmware/acpi/tables/data/BERT will cause a splat because
>> the data is I/O memory mapped and being read with just a memcpy.
>> Fix this by introducing an I/O variant of memory_read_from_buffer
>> and using I/O memory mapped copies instead.
>>
>> Fixes the following splat:
>>
>> [  439.789355] Unable to handle kernel paging request at virtual address ffff800041ac0007
>> [  439.797275] Mem abort info:
>> [  439.800078]   ESR = 0x96000021
>> [  439.803131]   EC = 0x25: DABT (current EL), IL = 32 bits
>> [  439.808437]   SET = 0, FnV = 0
>> [  439.811486]   EA = 0, S1PTW = 0
>> [  439.814621] Data abort info:
>> [  439.817489]   ISV = 0, ISS = 0x00000021
>> [  439.821319]   CM = 0, WnR = 0
>> [  439.824282] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000817fc000
>> [  439.830979] [ffff800041ac0007] pgd=000000bffcfff003, pud=0000009f27cee003, pmd=000000bf4b993003, pte=0068000080280703
>> [  439.841584] Internal error: Oops: 96000021 [#1] SMP
>> [  439.846449] Modules linked in: nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua ipmi_ssif input_leds joydev ipmi_devintf ipmi_msghandler thunderx2_pmu sch_fq_codel ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq libcrc32c raid1 raid0 multipath linear i2c_smbus ast i2c_algo_bit crct10dif_ce drm_vram_helper uas ttm ghash_ce drm_kms_helper sha2_ce syscopyarea sha256_arm64 qede sysfillrect mpt3sas sha1_ce sysimgblt fb_sys_fops raid_class qed drm scsi_transport_sas usb_storage ahci crc8 gpio_xlp i2c_xlp9xx hid_generic usbhid hid aes_neon_bs aes_neon_blk aes_ce_blk crypto_simd cryptd aes_ce_cipher
>> [  439.908474] CPU: 2 PID: 3926 Comm: a.out Not tainted 5.4.0-14-generic #17-Ubuntu
>> [  439.915855] Hardware name: To be filled by O.E.M. Saber/Saber, BIOS 0ACKL027 07/01/2019
>> [  439.923844] pstate: 80400009 (Nzcv daif +PAN -UAO)
>> [  439.928625] pc : __memcpy+0x90/0x180
>> [  439.932192] lr : memory_read_from_buffer+0x64/0x88
>> [  439.936968] sp : ffff8000350dbc70
>> [  439.940270] x29: ffff8000350dbc70 x28: ffff009e9c444b00
>> [  439.945568] x27: 0000000000000000 x26: 0000000000000000
>> [  439.950866] x25: 0000000056000000 x24: ffff800041ac0000
>> [  439.956164] x23: ffff009ea163f980 x22: 0000000000000007
>> [  439.961462] x21: ffff8000350dbce8 x20: 000000000000000e
>> [  439.966760] x19: 0000000000000007 x18: ffff8000112f64a8
>> [  439.972058] x17: 0000000000000000 x16: 0000000000000000
>> [  439.977355] x15: 0000000080280000 x14: ffff800041aed000
>> [  439.982653] x13: ffff009ee9fa2840 x12: ffff800041ad1000
>> [  439.987951] x11: ffff8000115e1360 x10: ffff8000115e1360
>> [  439.993248] x9 : 0000000000010000 x8 : ffff800011ad2658
>> [  439.998546] x7 : ffff800041ac0000 x6 : ffff009ea163f980
>> [  440.003844] x5 : 0140000000000000 x4 : 0000000000010000
>> [  440.009141] x3 : ffff800041ac0000 x2 : 0000000000000007
>> [  440.014439] x1 : ffff800041ac0007 x0 : ffff009ea163f980
>> [  440.019737] Call trace:
>> [  440.022173]  __memcpy+0x90/0x180
>> [  440.025392]  acpi_data_show+0x54/0x80
>> [  440.029044]  sysfs_kf_bin_read+0x6c/0xa8
>> [  440.032954]  kernfs_file_direct_read+0x90/0x2d0
>> [  440.037470]  kernfs_fop_read+0x68/0x78
>> [  440.041210]  __vfs_read+0x48/0x90
>> [  440.044511]  vfs_read+0xd0/0x1a0
>> [  440.047726]  ksys_read+0x78/0x100
>> [  440.051028]  __arm64_sys_read+0x24/0x30
>> [  440.054852]  el0_svc_common.constprop.0+0xdc/0x1d8
>> [  440.059629]  el0_svc_handler+0x34/0xa0
>> [  440.063366]  el0_svc+0x10/0x14
>> [  440.066411] Code: 36180062 f8408423 f80084c3 36100062 (b8404423)
>> [  440.072492] ---[ end trace 45fb374e8d2d800e ]---
>>
>> A simple reproducer is as follows:
>>
>> #include <sys/types.h>
>> #include <sys/stat.h>
>> #include <fcntl.h>
>> #include <unistd.h>
>> #include <stdio.h>
>> #include <string.h>
>>
>> int main(void)
>> {
>>         int fd;
>>         char buffer[7];
>>         ssize_t n;
>>
>>         fd = open("/sys/firmware/acpi/tables/data/BERT", O_RDONLY);
>>         if (fd < 0) {
>>                 perror("open failed");
>>                 return -1;
>>         }
>>         do {
>>                 n = read(fd, buffer, sizeof(buffer));
>>         } while (n > 0);
>>
>>         return 0;
>> }
>>
>> BugLink: https://bugs.launchpad.net/bugs/1866772
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>>  drivers/acpi/sysfs.c   |  2 +-
>>  fs/libfs.c             | 33 +++++++++++++++++++++++++++++++++
>>  include/linux/string.h |  2 ++
>>  3 files changed, 36 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
>> index c60d2c6d31d6..fb9e216cb8c0 100644
>> --- a/drivers/acpi/sysfs.c
>> +++ b/drivers/acpi/sysfs.c
>> @@ -446,7 +446,7 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
>>  	base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
>>  	if (!base)
>>  		return -ENOMEM;
>> -	rc = memory_read_from_buffer(buf, count, &offset, base,
>> +	rc = memory_read_from_io_buffer(buf, count, &offset, base,
>>  				     data_attr->attr.size);
>>  	acpi_os_unmap_memory(base, data_attr->attr.size);
>>  
>> diff --git a/fs/libfs.c b/fs/libfs.c
>> index c686bd9caac6..3e112c51ce7b 100644
>> --- a/fs/libfs.c
>> +++ b/fs/libfs.c
>> @@ -800,6 +800,39 @@ ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
>>  }
>>  EXPORT_SYMBOL(memory_read_from_buffer);
>>  
>> +/**
>> + * memory_read_from_io_buffer - copy data from a io memory mapped buffer
>> + * @to: the kernel space buffer to read to
>> + * @count: the maximum number of bytes to read
>> + * @ppos: the current position in the buffer
>> + * @from: the buffer to read from
>> + * @available: the size of the buffer
>> + *
>> + * The memory_read_from_buffer() function reads up to @count bytes from the
>> + * io memory mappy buffer @from at offset @ppos into the kernel space address
>> + * starting at @to.
>> + *
>> + * On success, the number of bytes read is returned and the offset @ppos is
>> + * advanced by this number, or negative value is returned on error.
>> + **/
>> +ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
>> +				   const void *from, size_t available)
>> +{
>> +	loff_t pos = *ppos;
>> +
>> +	if (pos < 0)
>> +		return -EINVAL;
>> +	if (pos >= available)
>> +		return 0;
>> +	if (count > available - pos)
>> +		count = available - pos;
>> +	memcpy_fromio(to, from + pos, count);
>> +	*ppos = pos + count;
>> +
>> +	return count;
>> +}
>> +EXPORT_SYMBOL(memory_read_from_io_buffer);
>> +
>>  /*
>>   * Transaction based IO.
>>   * The file expects a single write which triggers the transaction, and then
>> diff --git a/include/linux/string.h b/include/linux/string.h
>> index 6dfbb2efa815..0c6ec2aa3909 100644
>> --- a/include/linux/string.h
>> +++ b/include/linux/string.h
>> @@ -216,6 +216,8 @@ int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
>>  
>>  extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
>>  				       const void *from, size_t available);
>> +extern ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
>> +					  const void *from, size_t available);
>>  
>>  int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);
>>  
>>
> 
> Applied as 5.7 material, thanks!
> 
> 
> 
> 
Hi, what's the state of this patch, it got applied but I don't see it in
5.7, 5.8 or 5.8-rc3?

Colin
Sedat Dilek Sept. 2, 2020, 10:47 a.m. UTC | #3
On Wed, Sep 2, 2020 at 12:30 PM Colin Ian King <colin.king@canonical.com> wrote:
>
> On 14/03/2020 10:23, Rafael J. Wysocki wrote:
> > On Thursday, March 12, 2020 12:13:45 PM CET Colin King wrote:
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> Reading ACPI data on ARM64 at a non-aligned offset from
> >> /sys/firmware/acpi/tables/data/BERT will cause a splat because
> >> the data is I/O memory mapped and being read with just a memcpy.
> >> Fix this by introducing an I/O variant of memory_read_from_buffer
> >> and using I/O memory mapped copies instead.
> >>
> >> Fixes the following splat:
> >>
> >> [  439.789355] Unable to handle kernel paging request at virtual address ffff800041ac0007
> >> [  439.797275] Mem abort info:
> >> [  439.800078]   ESR = 0x96000021
> >> [  439.803131]   EC = 0x25: DABT (current EL), IL = 32 bits
> >> [  439.808437]   SET = 0, FnV = 0
> >> [  439.811486]   EA = 0, S1PTW = 0
> >> [  439.814621] Data abort info:
> >> [  439.817489]   ISV = 0, ISS = 0x00000021
> >> [  439.821319]   CM = 0, WnR = 0
> >> [  439.824282] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000817fc000
> >> [  439.830979] [ffff800041ac0007] pgd=000000bffcfff003, pud=0000009f27cee003, pmd=000000bf4b993003, pte=0068000080280703
> >> [  439.841584] Internal error: Oops: 96000021 [#1] SMP
> >> [  439.846449] Modules linked in: nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua ipmi_ssif input_leds joydev ipmi_devintf ipmi_msghandler thunderx2_pmu sch_fq_codel ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq libcrc32c raid1 raid0 multipath linear i2c_smbus ast i2c_algo_bit crct10dif_ce drm_vram_helper uas ttm ghash_ce drm_kms_helper sha2_ce syscopyarea sha256_arm64 qede sysfillrect mpt3sas sha1_ce sysimgblt fb_sys_fops raid_class qed drm scsi_transport_sas usb_storage ahci crc8 gpio_xlp i2c_xlp9xx hid_generic usbhid hid aes_neon_bs aes_neon_blk aes_ce_blk crypto_simd cryptd aes_ce_cipher
> >> [  439.908474] CPU: 2 PID: 3926 Comm: a.out Not tainted 5.4.0-14-generic #17-Ubuntu
> >> [  439.915855] Hardware name: To be filled by O.E.M. Saber/Saber, BIOS 0ACKL027 07/01/2019
> >> [  439.923844] pstate: 80400009 (Nzcv daif +PAN -UAO)
> >> [  439.928625] pc : __memcpy+0x90/0x180
> >> [  439.932192] lr : memory_read_from_buffer+0x64/0x88
> >> [  439.936968] sp : ffff8000350dbc70
> >> [  439.940270] x29: ffff8000350dbc70 x28: ffff009e9c444b00
> >> [  439.945568] x27: 0000000000000000 x26: 0000000000000000
> >> [  439.950866] x25: 0000000056000000 x24: ffff800041ac0000
> >> [  439.956164] x23: ffff009ea163f980 x22: 0000000000000007
> >> [  439.961462] x21: ffff8000350dbce8 x20: 000000000000000e
> >> [  439.966760] x19: 0000000000000007 x18: ffff8000112f64a8
> >> [  439.972058] x17: 0000000000000000 x16: 0000000000000000
> >> [  439.977355] x15: 0000000080280000 x14: ffff800041aed000
> >> [  439.982653] x13: ffff009ee9fa2840 x12: ffff800041ad1000
> >> [  439.987951] x11: ffff8000115e1360 x10: ffff8000115e1360
> >> [  439.993248] x9 : 0000000000010000 x8 : ffff800011ad2658
> >> [  439.998546] x7 : ffff800041ac0000 x6 : ffff009ea163f980
> >> [  440.003844] x5 : 0140000000000000 x4 : 0000000000010000
> >> [  440.009141] x3 : ffff800041ac0000 x2 : 0000000000000007
> >> [  440.014439] x1 : ffff800041ac0007 x0 : ffff009ea163f980
> >> [  440.019737] Call trace:
> >> [  440.022173]  __memcpy+0x90/0x180
> >> [  440.025392]  acpi_data_show+0x54/0x80
> >> [  440.029044]  sysfs_kf_bin_read+0x6c/0xa8
> >> [  440.032954]  kernfs_file_direct_read+0x90/0x2d0
> >> [  440.037470]  kernfs_fop_read+0x68/0x78
> >> [  440.041210]  __vfs_read+0x48/0x90
> >> [  440.044511]  vfs_read+0xd0/0x1a0
> >> [  440.047726]  ksys_read+0x78/0x100
> >> [  440.051028]  __arm64_sys_read+0x24/0x30
> >> [  440.054852]  el0_svc_common.constprop.0+0xdc/0x1d8
> >> [  440.059629]  el0_svc_handler+0x34/0xa0
> >> [  440.063366]  el0_svc+0x10/0x14
> >> [  440.066411] Code: 36180062 f8408423 f80084c3 36100062 (b8404423)
> >> [  440.072492] ---[ end trace 45fb374e8d2d800e ]---
> >>
> >> A simple reproducer is as follows:
> >>
> >> #include <sys/types.h>
> >> #include <sys/stat.h>
> >> #include <fcntl.h>
> >> #include <unistd.h>
> >> #include <stdio.h>
> >> #include <string.h>
> >>
> >> int main(void)
> >> {
> >>         int fd;
> >>         char buffer[7];
> >>         ssize_t n;
> >>
> >>         fd = open("/sys/firmware/acpi/tables/data/BERT", O_RDONLY);
> >>         if (fd < 0) {
> >>                 perror("open failed");
> >>                 return -1;
> >>         }
> >>         do {
> >>                 n = read(fd, buffer, sizeof(buffer));
> >>         } while (n > 0);
> >>
> >>         return 0;
> >> }
> >>
> >> BugLink: https://bugs.launchpad.net/bugs/1866772
> >> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >> ---
> >>  drivers/acpi/sysfs.c   |  2 +-
> >>  fs/libfs.c             | 33 +++++++++++++++++++++++++++++++++
> >>  include/linux/string.h |  2 ++
> >>  3 files changed, 36 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
> >> index c60d2c6d31d6..fb9e216cb8c0 100644
> >> --- a/drivers/acpi/sysfs.c
> >> +++ b/drivers/acpi/sysfs.c
> >> @@ -446,7 +446,7 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
> >>      base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
> >>      if (!base)
> >>              return -ENOMEM;
> >> -    rc = memory_read_from_buffer(buf, count, &offset, base,
> >> +    rc = memory_read_from_io_buffer(buf, count, &offset, base,
> >>                                   data_attr->attr.size);
> >>      acpi_os_unmap_memory(base, data_attr->attr.size);
> >>
> >> diff --git a/fs/libfs.c b/fs/libfs.c
> >> index c686bd9caac6..3e112c51ce7b 100644
> >> --- a/fs/libfs.c
> >> +++ b/fs/libfs.c
> >> @@ -800,6 +800,39 @@ ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
> >>  }
> >>  EXPORT_SYMBOL(memory_read_from_buffer);
> >>
> >> +/**
> >> + * memory_read_from_io_buffer - copy data from a io memory mapped buffer
> >> + * @to: the kernel space buffer to read to
> >> + * @count: the maximum number of bytes to read
> >> + * @ppos: the current position in the buffer
> >> + * @from: the buffer to read from
> >> + * @available: the size of the buffer
> >> + *
> >> + * The memory_read_from_buffer() function reads up to @count bytes from the
> >> + * io memory mappy buffer @from at offset @ppos into the kernel space address
> >> + * starting at @to.
> >> + *
> >> + * On success, the number of bytes read is returned and the offset @ppos is
> >> + * advanced by this number, or negative value is returned on error.
> >> + **/
> >> +ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
> >> +                               const void *from, size_t available)
> >> +{
> >> +    loff_t pos = *ppos;
> >> +
> >> +    if (pos < 0)
> >> +            return -EINVAL;
> >> +    if (pos >= available)
> >> +            return 0;
> >> +    if (count > available - pos)
> >> +            count = available - pos;
> >> +    memcpy_fromio(to, from + pos, count);
> >> +    *ppos = pos + count;
> >> +
> >> +    return count;
> >> +}
> >> +EXPORT_SYMBOL(memory_read_from_io_buffer);
> >> +
> >>  /*
> >>   * Transaction based IO.
> >>   * The file expects a single write which triggers the transaction, and then
> >> diff --git a/include/linux/string.h b/include/linux/string.h
> >> index 6dfbb2efa815..0c6ec2aa3909 100644
> >> --- a/include/linux/string.h
> >> +++ b/include/linux/string.h
> >> @@ -216,6 +216,8 @@ int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
> >>
> >>  extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
> >>                                     const void *from, size_t available);
> >> +extern ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
> >> +                                      const void *from, size_t available);
> >>
> >>  int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);
> >>
> >>
> >
> > Applied as 5.7 material, thanks!
> >
> >
> >
> >
> Hi, what's the state of this patch, it got applied but I don't see it in
> 5.7, 5.8 or 5.8-rc3?
>

s/5.8-rc3/5.9-rc3

- Sedat -
David Laight Sept. 2, 2020, 11:13 a.m. UTC | #4
From: Colin Ian King
> Sent: 02 September 2020 11:27
> 
> On 14/03/2020 10:23, Rafael J. Wysocki wrote:
> > On Thursday, March 12, 2020 12:13:45 PM CET Colin King wrote:
> >> From: Colin Ian King <colin.king@canonical.com>
> >>
> >> Reading ACPI data on ARM64 at a non-aligned offset from
> >> /sys/firmware/acpi/tables/data/BERT will cause a splat because
> >> the data is I/O memory mapped and being read with just a memcpy.
> >> Fix this by introducing an I/O variant of memory_read_from_buffer
> >> and using I/O memory mapped copies instead.
..
> >> +/**
> >> + * memory_read_from_io_buffer - copy data from a io memory mapped buffer
> >> + * @to: the kernel space buffer to read to
> >> + * @count: the maximum number of bytes to read
> >> + * @ppos: the current position in the buffer
> >> + * @from: the buffer to read from
> >> + * @available: the size of the buffer
> >> + *
> >> + * The memory_read_from_buffer() function reads up to @count bytes from the
> >> + * io memory mappy buffer @from at offset @ppos into the kernel space address
> >> + * starting at @to.
> >> + *
> >> + * On success, the number of bytes read is returned and the offset @ppos is
> >> + * advanced by this number, or negative value is returned on error.
> >> + **/

Apart from the return value how is this different from the generic
memcpy_from_io() ?

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
Colin Ian King Sept. 2, 2020, 11:48 a.m. UTC | #5
On 02/09/2020 12:13, David Laight wrote:
> From: Colin Ian King
>> Sent: 02 September 2020 11:27
>>
>> On 14/03/2020 10:23, Rafael J. Wysocki wrote:
>>> On Thursday, March 12, 2020 12:13:45 PM CET Colin King wrote:
>>>> From: Colin Ian King <colin.king@canonical.com>
>>>>
>>>> Reading ACPI data on ARM64 at a non-aligned offset from
>>>> /sys/firmware/acpi/tables/data/BERT will cause a splat because
>>>> the data is I/O memory mapped and being read with just a memcpy.
>>>> Fix this by introducing an I/O variant of memory_read_from_buffer
>>>> and using I/O memory mapped copies instead.
> ..
>>>> +/**
>>>> + * memory_read_from_io_buffer - copy data from a io memory mapped buffer
>>>> + * @to: the kernel space buffer to read to
>>>> + * @count: the maximum number of bytes to read
>>>> + * @ppos: the current position in the buffer
>>>> + * @from: the buffer to read from
>>>> + * @available: the size of the buffer
>>>> + *
>>>> + * The memory_read_from_buffer() function reads up to @count bytes from the
>>>> + * io memory mappy buffer @from at offset @ppos into the kernel space address
>>>> + * starting at @to.
>>>> + *
>>>> + * On success, the number of bytes read is returned and the offset @ppos is
>>>> + * advanced by this number, or negative value is returned on error.
>>>> + **/
> 
> Apart from the return value how is this different from the generic
> memcpy_from_io() ?
> 
> 	David


The intention is to be semantically the same as
memory_read_from_buffer(), so in that respect quite a bit different from
memcpy_fromio()

Colin

> 
> -
> Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> Registration No: 1397386 (Wales)
>

Patch
diff mbox series

diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
index c60d2c6d31d6..fb9e216cb8c0 100644
--- a/drivers/acpi/sysfs.c
+++ b/drivers/acpi/sysfs.c
@@ -446,7 +446,7 @@  static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj,
 	base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size);
 	if (!base)
 		return -ENOMEM;
-	rc = memory_read_from_buffer(buf, count, &offset, base,
+	rc = memory_read_from_io_buffer(buf, count, &offset, base,
 				     data_attr->attr.size);
 	acpi_os_unmap_memory(base, data_attr->attr.size);
 
diff --git a/fs/libfs.c b/fs/libfs.c
index c686bd9caac6..3e112c51ce7b 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -800,6 +800,39 @@  ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
 }
 EXPORT_SYMBOL(memory_read_from_buffer);
 
+/**
+ * memory_read_from_io_buffer - copy data from a io memory mapped buffer
+ * @to: the kernel space buffer to read to
+ * @count: the maximum number of bytes to read
+ * @ppos: the current position in the buffer
+ * @from: the buffer to read from
+ * @available: the size of the buffer
+ *
+ * The memory_read_from_buffer() function reads up to @count bytes from the
+ * io memory mappy buffer @from at offset @ppos into the kernel space address
+ * starting at @to.
+ *
+ * On success, the number of bytes read is returned and the offset @ppos is
+ * advanced by this number, or negative value is returned on error.
+ **/
+ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
+				   const void *from, size_t available)
+{
+	loff_t pos = *ppos;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= available)
+		return 0;
+	if (count > available - pos)
+		count = available - pos;
+	memcpy_fromio(to, from + pos, count);
+	*ppos = pos + count;
+
+	return count;
+}
+EXPORT_SYMBOL(memory_read_from_io_buffer);
+
 /*
  * Transaction based IO.
  * The file expects a single write which triggers the transaction, and then
diff --git a/include/linux/string.h b/include/linux/string.h
index 6dfbb2efa815..0c6ec2aa3909 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -216,6 +216,8 @@  int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
 
 extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
 				       const void *from, size_t available);
+extern ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos,
+					  const void *from, size_t available);
 
 int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);