Andy Lutomirski 3fb0fdb3bb x86/stackprotector/32: Make the canary into a regular percpu variable ... On 32-bit kernels, the stackprotector canary is quite nasty -- it is stored at %gs:(20), which is nasty because 32-bit kernels use %fs for percpu storage. It's even nastier because it means that whether %gs contains userspace state or kernel state while running kernel code depends on whether stackprotector is enabled (this is CONFIG_X86_32_LAZY_GS), and this setting radically changes the way that segment selectors work. Supporting both variants is a maintenance and testing mess. Merely rearranging so that percpu and the stack canary share the same segment would be messy as the 32-bit percpu address layout isn't currently compatible with putting a variable at a fixed offset. Fortunately, GCC 8.1 added options that allow the stack canary to be accessed as %fs:__stack_chk_guard, effectively turning it into an ordinary percpu variable. This lets us get rid of all of the code to manage the stack canary GDT descriptor and the CONFIG_X86_32_LAZY_GS mess. (That name is special. We could use any symbol we want for the %fs-relative mode, but for CONFIG_SMP=n, gcc refuses to let us use any name other than __stack_chk_guard.) Forcibly disable stackprotector on older compilers that don't support the new options and turn the stack canary into a percpu variable. The "lazy GS" approach is now used for all 32-bit configurations. Also makes load_gs_index() work on 32-bit kernels. On 64-bit kernels, it loads the GS selector and updates the user GSBASE accordingly. (This is unchanged.) On 32-bit kernels, it loads the GS selector and updates GSBASE, which is now always the user base. This means that the overall effect is the same on 32-bit and 64-bit, which avoids some ifdeffery. [ bp: Massage commit message. ] Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/c0ff7dba14041c7e5d1cae5d4df052f03759bef3.1613243844.git.luto@kernel.org		2021-03-08 13:19:05 +01:00
..
alpha	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
arc	arch: setup PF_IO_WORKER threads like PF_KTHREAD	2021-02-21 17:25:22 -07:00
arm	xen: branch for v5.12-rc2	2021-03-04 11:24:47 -08:00
arm64	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
csky	arch/csky patches for 5.12-rc1	2021-02-28 12:06:45 -08:00
h8300	arch: setup PF_IO_WORKER threads like PF_KTHREAD	2021-02-21 17:25:22 -07:00
hexagon	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
ia64	ia64: don't call handle_signal() unless there's actually a signal queued	2021-03-02 17:22:11 -07:00
m68k	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
microblaze	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
mips	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
nds32	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
nios2	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
openrisc	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
parisc	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
powerpc	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
riscv	RISC-V Patches for the 5.12 Merge Window, Part 2	2021-02-28 12:01:23 -08:00
s390	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
sh	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
sparc	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
um	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
x86	x86/stackprotector/32: Make the canary into a regular percpu variable	2021-03-08 13:19:05 +01:00
xtensa	io_uring-worker.v3-2021-02-25	2021-02-27 08:29:02 -08:00
.gitignore
Kconfig	Rework of the X86 irq stack handling:	2021-02-24 16:32:23 -08:00