linux_dsm_epyc7002/arch/x86/kernel/trampoline.c

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#include <linux/io.h>
#include <linux/memblock.h>
#include <asm/trampoline.h>
x86-32: Separate 1:1 pagetables from swapper_pg_dir This patch fixes machine crashes which occur when heavily exercising the CPU hotplug codepaths on a 32-bit kernel. These crashes are caused by AMD Erratum 383 and result in a fatal machine check exception. Here's the scenario: 1. On 32-bit, the swapper_pg_dir page table is used as the initial page table for booting a secondary CPU. 2. To make this work, swapper_pg_dir needs a direct mapping of physical memory in it (the low mappings). By adding those low, large page (2M) mappings (PAE kernel), we create the necessary conditions for Erratum 383 to occur. 3. Other CPUs which do not participate in the off- and onlining game may use swapper_pg_dir while the low mappings are present (when leave_mm is called). For all steps below, the CPU referred to is a CPU that is using swapper_pg_dir, and not the CPU which is being onlined. 4. The presence of the low mappings in swapper_pg_dir can result in TLB entries for addresses below __PAGE_OFFSET to be established speculatively. These TLB entries are marked global and large. 5. When the CPU with such TLB entry switches to another page table, this TLB entry remains because it is global. 6. The process then generates an access to an address covered by the above TLB entry but there is a permission mismatch - the TLB entry covers a large global page not accessible to userspace. 7. Due to this permission mismatch a new 4kb, user TLB entry gets established. Further, Erratum 383 provides for a small window of time where both TLB entries are present. This results in an uncorrectable machine check exception signalling a TLB multimatch which panics the machine. There are two ways to fix this issue: 1. Always do a global TLB flush when a new cr3 is loaded and the old page table was swapper_pg_dir. I consider this a hack hard to understand and with performance implications 2. Do not use swapper_pg_dir to boot secondary CPUs like 64-bit does. This patch implements solution 2. It introduces a trampoline_pg_dir which has the same layout as swapper_pg_dir with low_mappings. This page table is used as the initial page table of the booting CPU. Later in the bringup process, it switches to swapper_pg_dir and does a global TLB flush. This fixes the crashes in our test cases. -v2: switch to swapper_pg_dir right after entering start_secondary() so that we are able to access percpu data which might not be mapped in the trampoline page table. Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> LKML-Reference: <20100816123833.GB28147@aftab> Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-08-16 19:38:33 +07:00
#include <asm/pgtable.h>
#if defined(CONFIG_X86_64) && defined(CONFIG_ACPI_SLEEP)
#define __trampinit
#define __trampinitdata
#else
#define __trampinit __cpuinit
#define __trampinitdata __cpuinitdata
#endif
x86: extend e820 ealy_res support 32bit move early_res related from e820_64.c to e820.c make edba detection to be done in head32.c remove smp_alloc_memory, because we have fixed trampoline address now. Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com> arch/x86/kernel/e820.c | 214 ++++++++++++++++++++++++++++++++++++ arch/x86/kernel/e820_64.c | 196 -------------------------------- arch/x86/kernel/head32.c | 76 ++++++++++++ arch/x86/kernel/setup_32.c | 109 +++--------------- arch/x86/kernel/smpboot.c | 17 -- arch/x86/kernel/trampoline.c | 2 arch/x86/mach-voyager/voyager_smp.c | 9 - include/asm-x86/e820.h | 6 + include/asm-x86/e820_64.h | 9 - include/asm-x86/smp.h | 1 arch/x86/kernel/e820.c | 214 ++++++++++++++++++++++++++++++++++++ arch/x86/kernel/e820_64.c | 196 -------------------------------- arch/x86/kernel/head32.c | 76 ++++++++++++ arch/x86/kernel/setup_32.c | 109 +++--------------- arch/x86/kernel/smpboot.c | 17 -- arch/x86/kernel/trampoline.c | 2 arch/x86/mach-voyager/voyager_smp.c | 9 - include/asm-x86/e820.h | 6 + include/asm-x86/e820_64.h | 9 - include/asm-x86/smp.h | 1 arch/x86/kernel/e820.c | 214 ++++++++++++++++++++++++++++++++++++ arch/x86/kernel/e820_64.c | 196 -------------------------------- arch/x86/kernel/head32.c | 76 ++++++++++++ arch/x86/kernel/setup_32.c | 109 +++--------------- arch/x86/kernel/smpboot.c | 17 -- arch/x86/kernel/trampoline.c | 2 arch/x86/mach-voyager/voyager_smp.c | 9 - include/asm-x86/e820.h | 6 + include/asm-x86/e820_64.h | 9 - include/asm-x86/smp.h | 1 10 files changed, 320 insertions(+), 319 deletions(-) Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-05-18 15:18:57 +07:00
/* ready for x86_64 and x86 */
unsigned char *__trampinitdata trampoline_base;
void __init reserve_trampoline_memory(void)
{
phys_addr_t mem;
/* Has to be in very low memory so we can execute real-mode AP code. */
mem = memblock_find_in_range(0, 1<<20, TRAMPOLINE_SIZE, PAGE_SIZE);
if (mem == MEMBLOCK_ERROR)
panic("Cannot allocate trampoline\n");
trampoline_base = __va(mem);
memblock_x86_reserve_range(mem, mem + TRAMPOLINE_SIZE, "TRAMPOLINE");
}
/*
* Currently trivial. Write the real->protected mode
* bootstrap into the page concerned. The caller
* has made sure it's suitably aligned.
*/
unsigned long __trampinit setup_trampoline(void)
{
memcpy(trampoline_base, trampoline_data, TRAMPOLINE_SIZE);
return virt_to_phys(trampoline_base);
}