x86/crash: Remove crash_reserve_low_1M()

The entire memory range under 1M is unconditionally reserved in
setup_arch(), so there is no need for crash_reserve_low_1M() anymore.

Remove this function.
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210601075354.5149-4-rppt@kernel.org

arch/x86/include/asm/crash.h

@@ -9,10 +9,4 @@ int crash_setup_memmap_entries(struct kimage *image,
 		struct boot_params *params);
 void crash_smp_send_stop(void);
 
-#ifdef CONFIG_KEXEC_CORE
-void __init crash_reserve_low_1M(void);
-#else
-static inline void __init crash_reserve_low_1M(void) { }
-#endif
-
 #endif /* _ASM_X86_CRASH_H */

arch/x86/kernel/crash.c

@@ -70,19 +70,6 @@ static inline void cpu_crash_vmclear_loaded_vmcss(void)
 	rcu_read_unlock();
 }
 
-/*
- * When the crashkernel option is specified, only use the low
- * 1M for the real mode trampoline.
- */
-void __init crash_reserve_low_1M(void)
-{
-	if (cmdline_find_option(boot_command_line, "crashkernel", NULL, 0) < 0)
-		return;
-
-	memblock_reserve(0, 1<<20);
-	pr_info("Reserving the low 1M of memory for crashkernel\n");
-}
-
 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
 
 static void kdump_nmi_callback(int cpu, struct pt_regs *regs)