From 4f5f23846d6713c05481c8cfc710bb23817bf5e9 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Wed, 5 Aug 2026 23:28:35 +0200 Subject: rust: io: gate ioremap/iounmap on CONFIG_HAS_IOMEM s390 does not provide ioremap()/iounmap() when CONFIG_HAS_IOMEM is not set (which requires CONFIG_PCI on that architecture). This causes a build failure with Rust enabled on e.g. s390 allnoconfig: In file included from rust/helpers/helpers.c:68: rust/helpers/io.c:8:9: error: call to undeclared function 'ioremap'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 8 | return ioremap(offset, size); | ^ rust/helpers/io.c:19:2: error: call to undeclared function 'iounmap'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration] 19 | iounmap(addr); Guard the C helpers behind #ifdef CONFIG_HAS_IOMEM and cfg-gate the Rust io::mem module, such that IoMem, ExclusiveIoMem and IoRequest are not available without CONFIG_HAS_IOMEM. Note that the C API is inconsistent about this. For instance, devm_ioremap() has no stub and produces a link failure without CONFIG_HAS_IOMEM, whereas devm_platform_ioremap_resource() provides an inline stub returning -EINVAL. The approach taken here (compile-time gating) matches the former, which is slightly more appropriate since any driver performing MMIO currently requires CONFIG_HAS_IOMEM. Ideally, s390 should provide ioremap()/iounmap() stubs unconditionally (as UML already does), removing the need for any config gating as discussed in [1]; a follow-up patch for s390 is expected. Cc: Arnd Bergmann Reported-by: Miguel Ojeda Closes: https://lore.kernel.org/all/20260803180931.97202-1-ojeda@kernel.org [1] Fixes: 3f70ebe63858 ("s390: Enable Rust support") Reviewed-by: Arnd Bergmann Link: https://patch.msgid.link/20260805212920.1996937-1-dakr@kernel.org Signed-off-by: Danilo Krummrich --- rust/helpers/io.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'rust/helpers') diff --git a/rust/helpers/io.c b/rust/helpers/io.c index 397810864a24..1edbc274951c 100644 --- a/rust/helpers/io.c +++ b/rust/helpers/io.c @@ -3,6 +3,7 @@ #include #include +#ifdef CONFIG_HAS_IOMEM __rust_helper void __iomem *rust_helper_ioremap(phys_addr_t offset, size_t size) { return ioremap(offset, size); @@ -18,6 +19,7 @@ __rust_helper void rust_helper_iounmap(void __iomem *addr) { iounmap(addr); } +#endif /* CONFIG_HAS_IOMEM */ __rust_helper u8 rust_helper_readb(const void __iomem *addr) { -- cgit v1.2.3