6.7-stable review patch. If anyone has any objections, please let me know.
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From: Michael Ellerman mpe@ellerman.id.au
[ Upstream commit f1acb109505d983779bbb7e20a1ee6244d2b5736 ]
KASAN is seen to increase stack usage, to the point that it was reported to lead to stack overflow on some 32-bit machines (see link).
To avoid overflows the stack size was doubled for KASAN builds in commit 3e8635fb2e07 ("powerpc/kasan: Force thread size increase with KASAN").
However with a 32KB stack size to begin with, the doubling leads to a 64KB stack, which causes build errors: arch/powerpc/kernel/switch.S:249: Error: operand out of range (0x000000000000fe50 is not between 0xffffffffffff8000 and 0x0000000000007fff)
Although the asm could be reworked, in practice a 32KB stack seems sufficient even for KASAN builds - the additional usage seems to be in the 2-3KB range for a 64-bit KASAN build.
So only increase the stack for KASAN if the stack size is < 32KB.
Fixes: 18f14afe2816 ("powerpc/64s: Increase default stack size to 32KB") Reported-by: Spoorthy spoorthy@linux.ibm.com Reported-by: Benjamin Gray bgray@linux.ibm.com Reviewed-by: Benjamin Gray bgray@linux.ibm.com Link: https://lore.kernel.org/linuxppc-dev/bug-207129-206035@https.bugzilla.kernel... Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://msgid.link/20240212064244.3924505-1-mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/include/asm/thread_info.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h index bf5dde1a4114..15c5691dd218 100644 --- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h @@ -14,7 +14,7 @@
#ifdef __KERNEL__
-#ifdef CONFIG_KASAN +#if defined(CONFIG_KASAN) && CONFIG_THREAD_SHIFT < 15 #define MIN_THREAD_SHIFT (CONFIG_THREAD_SHIFT + 1) #else #define MIN_THREAD_SHIFT CONFIG_THREAD_SHIFT