Re: [PATCH 5.15 00/59] 5.15.184-rc1 review

[Richard Narron]

On Fri, 23 May 2025, Guenter Roeck wrote:

> On 5/20/25 06:49, Greg Kroah-Hartman wrote:
> > This is the start of the stable review cycle for the 5.15.184 release.
> > There are 59 patches in this series, all will be posted as a response
> > to this one.  If anyone has any issues with these being applied, please
> > let me know.
> >
> > Responses should be made by Thu, 22 May 2025 12:57:37 +0000.
> > Anything received after that time might be too late.
> >
>
> Build reference: v5.15.184
> Compiler version: x86_64-linux-gcc (GCC) 12.4.0
> Assembler version: GNU assembler (GNU Binutils) 2.40
>
> Configuration file workarounds:
>     "s/CONFIG_FRAME_WARN=.*/CONFIG_FRAME_WARN=0/"
>
> Building i386:defconfig ... passed
> Building i386:allyesconfig ... failed
> --------------
> Error log:
> x86_64-linux-ld: arch/x86/kernel/static_call.o: in function
> `__static_call_transform':
> static_call.c:(.ref.text+0x46): undefined reference to `cpu_wants_rethunk_at'
> make[1]: [Makefile:1234: vmlinux] Error 1 (ignored)
> --------------
> Building i386:allmodconfig ... failed
> --------------
> Error log:
> x86_64-linux-ld: arch/x86/kernel/static_call.o: in function
> `__static_call_transform':
> static_call.c:(.ref.text+0x46): undefined reference to `cpu_wants_rethunk_at'
> make[1]: [Makefile:1234: vmlinux] Error 1 (ignored)
> --------------
>
> In v5.15.y, cpu_wants_rethunk_at is only built if CONFIG_STACK_VALIDATION=y,
> but that is not supported for i386 builds. The dummy function in
> arch/x86/include/asm/alternative.h doesn't take that dependency into account.
>

I found this bug too using the Slackware 15.0 32-bit kernel
configuration.

Here is a simple work around patch, but there may be a better solution...

--- arch/x86/kernel/static_call.c.orig	2025-05-22 05:08:28.000000000 -0700
+++ arch/x86/kernel/static_call.c	2025-05-27 10:25:27.630496538 -0700
@@ -81,9 +81,12 @@
 		break;

 	case RET:
+
+#ifdef CONFIG_64BIT
 		if (cpu_wants_rethunk_at(insn))
 			code = text_gen_insn(JMP32_INSN_OPCODE, insn, x86_return_thunk);
 		else
+#endif
 			code = &retinsn;
 		break;

--------------
Richard Narron