[PATCH v18 05/17] x86/setup: Use parse_crashkernel_in_order() to make code logic clear

Zhen Lei
2021-12-22T13:12:31Z

Currently, the parsing of "crashkernel=X,high" and the parsing of
"crashkernel=X,low" are not in the same function, but they are strongly
dependent, which affects readability. Use parse_crashkernel_in_order() to
bring them together.

In addition, the operation to ensure at least 256M low memory is moved out
of reserve_craskernel_low() so that it only needs to focus on low memory
allocation.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
---
arch/x86/kernel/setup.c | 69 ++++++++++++++++++-----------------------
1 file changed, 30 insertions(+), 39 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index f997074d36f2484..07a58313db5c5f7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -393,32 +393,16 @@ static void __init memblock_x86_reserve_range_setup_data(void)
#ifdef CONFIG_KEXEC_CORE

#ifdef CONFIG_X86_64
-static int __init reserve_crashkernel_low(void)
+static int __init reserve_crashkernel_low(unsigned long long low_size)
{
- unsigned long long base, low_base = 0, low_size = 0;
+ unsigned long long low_base = 0;
unsigned long low_mem_limit;
- int ret;

low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);

- /* crashkernel=Y,low */
- ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
- if (ret) {
- /*
- * two parts from kernel/dma/swiotlb.c:
- * -swiotlb size: user-specified with swiotlb= or default.
- *
- * -swiotlb overflow buffer: now hardcoded to 32k. We round it
- * to 8M for other buffers that may need to stay low too. Also
- * make sure we allocate enough extra low memory so that we
- * don't run out of DMA buffers for 32-bit devices.
- */
- low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
- } else {
- /* passed with crashkernel=0,low ? */
- if (!low_size)
- return 0;
- }
+ /* passed with crashkernel=0,low ? */
+ if (!low_size)
+ return 0;

low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
if (!low_base) {
@@ -457,7 +441,6 @@ static int __init reserve_crashkernel_low(void)
* Returns the status flag of the parsing result of "crashkernel=", such as
* CRASHKERNEL_MEM_NONE, CRASHKERNEL_MEM_HIGH.
*/
-__maybe_unused
static int __init parse_crashkernel_in_order(char *cmdline,
unsigned long long system_ram,
unsigned long long *crash_size,
@@ -492,22 +475,15 @@ static int __init parse_crashkernel_in_order(char *cmdline,

static void __init reserve_crashkernel(void)
{
- unsigned long long crash_size, crash_base, total_mem;
- bool high = false;
- int ret;
+ unsigned long long crash_size, crash_base, total_mem, low_size;
+ int flag;

total_mem = memblock_phys_mem_size();

- /* crashkernel=XM */
- ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
- if (ret != 0 || crash_size <= 0) {
- /* crashkernel=X,high */
- ret = parse_crashkernel_high(boot_command_line, total_mem,
- &crash_size, &crash_base);
- if (ret != 0 || crash_size <= 0)
- return;
- high = true;
- }
+ flag = parse_crashkernel_in_order(boot_command_line, total_mem,
+ &crash_size, &crash_base, &low_size);
+ if (flag == CRASHKERNEL_MEM_NONE)
+ return;

/* 0 means: find the address automatically */
if (!crash_base) {
@@ -519,7 +495,7 @@ static void __init reserve_crashkernel(void)
* So try low memory first and fall back to high memory
* unless "crashkernel=size[KMG],high" is specified.
*/
- if (!high)
+ if (!(flag & CRASHKERNEL_MEM_HIGH))
crash_base = memblock_phys_alloc_range(crash_size,
CRASH_ALIGN, CRASH_ALIGN,
CRASH_ADDR_LOW_MAX);
@@ -543,9 +519,24 @@ static void __init reserve_crashkernel(void)
}

#ifdef CONFIG_X86_64
- if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
- memblock_phys_free(crash_base, crash_size);
- return;
+ if (crash_base >= (1ULL << 32)) {
+ if (!(flag & CRASHKERNEL_MEM_LOW)) {
+ /*
+ * two parts from kernel/dma/swiotlb.c:
+ * -swiotlb size: user-specified with swiotlb= or default.
+ *
+ * -swiotlb overflow buffer: now hardcoded to 32k. We round it
+ * to 8M for other buffers that may need to stay low too. Also
+ * make sure we allocate enough extra low memory so that we
+ * don't run out of DMA buffers for 32-bit devices.
+ */
+ low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
+ }
+
+ if (reserve_crashkernel_low(low_size)) {
+ memblock_phys_free(crash_base, crash_size);
+ return;
+ }
}
#endif

--
2.25.1