| 2022-10-05 12:44:12 |
Alexandre Ghiti |
bug |
|
|
added bug |
| 2022-10-10 11:07:22 |
Emil Renner Berthing |
description |
[ Impact ]
sv57 breaks Go since Go uses the upper bits of a pointer to store data, and it is not ready for sv57 yet. It probably breaks other type of software using this "pointer tagging" technic. The following patch fixes this: at the moment, there is no way to indicate to the kernel to downgrade to sv48, so we must patch the kernel.
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2c4a64e97aec..18a0c70ed313 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -775,6 +775,10 @@ static __init void set_satp_mode(void)
disable_pgtable_l4();
}
+ /* UBUNTU: Force disable sv57 and fallback to sv48 */
+ if (pgtable_l5_enabled)
+ disable_pgtable_l5();
+
memset(early_pg_dir, 0, PAGE_SIZE);
memset(early_p4d, 0, PAGE_SIZE);
memset(early_pud, 0, PAGE_SIZE);
[ Test Plan ]
Build an image with the new kernel and make sure snapd started correctly, or that you can compile a simple helloworld written in Go.
[ Where problems could occur ]
The patch could be wrong, but I already built a kernel with it and it worked fine. |
[ Impact ]
* Linux 5.18 merged support for 5-level page tables (sv57), and it
does it such that 5-level page tables are used whenever the
system supports it.
* So far only Qemu support sv57, but it breaks Go since Go uses
too many of the upper bits of pointers to store data, and is not
yet ready for sv57. It probably breaks other types of software
using too many bits for this "pointer tagging" technique.
At the moment, there is no way to indicate to the kernel to
downgrade to sv48, so we must patch the kernel:
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2c4a64e97aec..18a0c70ed313 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -775,6 +775,10 @@ static __init void set_satp_mode(void)
disable_pgtable_l4();
}
+ /* UBUNTU: Force disable sv57 and fallback to sv48 */
+ if (pgtable_l5_enabled)
+ disable_pgtable_l5();
+
memset(early_pg_dir, 0, PAGE_SIZE);
memset(early_p4d, 0, PAGE_SIZE);
memset(early_pud, 0, PAGE_SIZE);
[ Test Plan ]
* Build an image with the patched kernel and make sure snapd and
other Go programs works correctly and that you can compile a
simple helloworld written in Go.
[ Where problems could occur ]
* The patch could be buggy.
* Qemu will no longer work with > 128 PB of memory. |
|
| 2022-10-10 11:08:52 |
Emil Renner Berthing |
description |
[ Impact ]
* Linux 5.18 merged support for 5-level page tables (sv57), and it
does it such that 5-level page tables are used whenever the
system supports it.
* So far only Qemu support sv57, but it breaks Go since Go uses
too many of the upper bits of pointers to store data, and is not
yet ready for sv57. It probably breaks other types of software
using too many bits for this "pointer tagging" technique.
At the moment, there is no way to indicate to the kernel to
downgrade to sv48, so we must patch the kernel:
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2c4a64e97aec..18a0c70ed313 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -775,6 +775,10 @@ static __init void set_satp_mode(void)
disable_pgtable_l4();
}
+ /* UBUNTU: Force disable sv57 and fallback to sv48 */
+ if (pgtable_l5_enabled)
+ disable_pgtable_l5();
+
memset(early_pg_dir, 0, PAGE_SIZE);
memset(early_p4d, 0, PAGE_SIZE);
memset(early_pud, 0, PAGE_SIZE);
[ Test Plan ]
* Build an image with the patched kernel and make sure snapd and
other Go programs works correctly and that you can compile a
simple helloworld written in Go.
[ Where problems could occur ]
* The patch could be buggy.
* Qemu will no longer work with > 128 PB of memory. |
[ Impact ]
* Linux 5.18 merged support for 5-level page tables (sv57), and it
does it such that 5-level page tables are used whenever the
system supports it.
* So far only Qemu support sv57, but it breaks Go since Go uses
too many of the upper bits of pointers to store data, and is not
yet ready for sv57. It probably breaks other types of software
using too many bits for this "pointer tagging" technique.
At the moment, there is no way to indicate to the kernel to
downgrade to sv48, so we must patch the kernel:
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2c4a64e97aec..18a0c70ed313 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -775,6 +775,10 @@ static __init void set_satp_mode(void)
disable_pgtable_l4();
}
+ /* UBUNTU: Force disable sv57 and fallback to sv48 */
+ if (pgtable_l5_enabled)
+ disable_pgtable_l5();
+
memset(early_pg_dir, 0, PAGE_SIZE);
memset(early_p4d, 0, PAGE_SIZE);
memset(early_pud, 0, PAGE_SIZE);
[ Test Plan ]
* Build an image with the patched kernel and make sure snapd and
other Go programs works correctly and that you can compile a
simple helloworld written in Go.
[ Where problems could occur ]
* The patch could be buggy.
* Qemu will no longer work with > 256 TB of memory. |
|
| 2022-10-10 11:14:52 |
Emil Renner Berthing |
description |
[ Impact ]
* Linux 5.18 merged support for 5-level page tables (sv57), and it
does it such that 5-level page tables are used whenever the
system supports it.
* So far only Qemu support sv57, but it breaks Go since Go uses
too many of the upper bits of pointers to store data, and is not
yet ready for sv57. It probably breaks other types of software
using too many bits for this "pointer tagging" technique.
At the moment, there is no way to indicate to the kernel to
downgrade to sv48, so we must patch the kernel:
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2c4a64e97aec..18a0c70ed313 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -775,6 +775,10 @@ static __init void set_satp_mode(void)
disable_pgtable_l4();
}
+ /* UBUNTU: Force disable sv57 and fallback to sv48 */
+ if (pgtable_l5_enabled)
+ disable_pgtable_l5();
+
memset(early_pg_dir, 0, PAGE_SIZE);
memset(early_p4d, 0, PAGE_SIZE);
memset(early_pud, 0, PAGE_SIZE);
[ Test Plan ]
* Build an image with the patched kernel and make sure snapd and
other Go programs works correctly and that you can compile a
simple helloworld written in Go.
[ Where problems could occur ]
* The patch could be buggy.
* Qemu will no longer work with > 256 TB of memory. |
[ Impact ]
* Linux 5.18 merged support for 5-level page tables (sv57), and it
does it such that 5-level page tables are used whenever the
system supports it.
* So far only Qemu support sv57, but it breaks Go since Go uses
too many of the upper bits of pointers to store data, and is not
yet ready for sv57. It probably breaks other types of software
using too many bits for this "pointer tagging" technique too.
At the moment, there is no way to indicate to the kernel to
downgrade to sv48, so we must patch the kernel:
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 2c4a64e97aec..18a0c70ed313 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -775,6 +775,10 @@ static __init void set_satp_mode(void)
disable_pgtable_l4();
}
+ /* UBUNTU: Force disable sv57 and fallback to sv48 */
+ if (pgtable_l5_enabled)
+ disable_pgtable_l5();
+
memset(early_pg_dir, 0, PAGE_SIZE);
memset(early_p4d, 0, PAGE_SIZE);
memset(early_pud, 0, PAGE_SIZE);
[ Test Plan ]
* Build an image with the patched kernel and make sure snapd and
other Go programs work correctly and that you can compile a
simple helloworld written in Go.
[ Where problems could occur ]
* The patch could be buggy.
* Qemu will no longer work with > 256 TB of memory. |
|
| 2022-10-10 17:45:28 |
Emil Renner Berthing |
linux-riscv (Ubuntu): assignee |
|
Emil Renner Berthing (esmil) |
|
| 2022-10-12 13:53:00 |
Launchpad Janitor |
linux-riscv (Ubuntu): status |
New |
Fix Released |
|
| 2022-10-12 13:53:00 |
Launchpad Janitor |
cve linked |
|
2022-2978 |
|
| 2022-12-07 15:37:07 |
Ubuntu Kernel Bot |
tags |
|
kernel-spammed-jammy-linux-hwe-5.19 verification-needed-jammy |
|
| 2023-05-23 14:12:59 |
Richard Jones |
bug |
|
|
added subscriber Richard Jones |
