powerpc/64e: Fix secondary thread bringup for ELFv2 kernels

When booting on e6500 with an ELF v2 ABI kernel, the secondary threads do
not start correctly:

    [    0.051118] smp: Bringing up secondary CPUs ...
    [    5.072700] Processor 1 is stuck.

This occurs because the startup code is written to use function
descriptors when loading the entry point for the secondary threads. When
building with ELF v2 ABI there are no function descriptors, and the code
loads junk values for the entry point address.

Fix it by using ppc_function_entry() in C, and DOTSYM() in asm, both of
which work correctly for ELF v2 ABI as well as ELF v1 ABI kernels.

Fixes: 8c5fa3b5c4df ("powerpc/64: Make ELFv2 the default for big-endian builds")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801102650.48705-1-mpe@ellerman.id.au

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index f132d8704263cd683f78eed26387aee0babef52c..6440b1bb332acfd7942020a65cd9f5461bc70546 100644 (file)
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -375,8 +375,7 @@ _GLOBAL(generic_secondary_smp_init)
        beq     20f
 
        /* start the specified thread */
-       LOAD_REG_ADDR(r5, fsl_secondary_thread_init)
-       ld      r4, 0(r5)
+       LOAD_REG_ADDR(r5, DOTSYM(fsl_secondary_thread_init))
        bl      book3e_start_thread
 
        /* stop the current thread */

diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
index 9c43cf32f4c9fc4f3be82c00978ea5e5f7acb654..40aa5820688831fd22cbfc2d7c1f4a0632f9fb67 100644 (file)
--- a/arch/powerpc/platforms/85xx/smp.c
+++ b/arch/powerpc/platforms/85xx/smp.c
@@ -180,7 +180,7 @@ static void wake_hw_thread(void *info)
        unsigned long inia;
        int cpu = *(const int *)info;
 
-       inia = *(unsigned long *)fsl_secondary_thread_init;
+       inia = ppc_function_entry(fsl_secondary_thread_init);
        book3e_start_thread(cpu_thread_in_core(cpu), inia);
 }
 #endif