From: Mahesh Salgaonkar <mahesh@xxxxxxxxxxxxxxxxxx> So far powerpc kernel never exported memory limit information which is reflected by mem= kernel cmdline option. Hence, kexec-tools always used to build ELF header for entire system RAM generating a dump bigger than the actual memory used by the first kernel. This patch now reads the memory limit information from device-tree file and limits the crash memory ranges accordingly. Suzuki tested this patch on ppc32(ppc440) with a kernel patch by Suzuki. The proposed upstream kernel patch at https://lists.ozlabs.org/pipermail/linuxppc-dev/2012-August/100500.html now exports memory limit information through /proc/device-tree file. Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com> Tested-by: Suzuki K. Poulose <suzuki at in.ibm.com> --- kexec/arch/ppc/crashdump-powerpc.c | 14 ++++++++--- kexec/arch/ppc/crashdump-powerpc.h | 1 + kexec/arch/ppc/kexec-ppc.c | 48 ++++++++++++++++++++++++++++++++++++ 3 files changed, 60 insertions(+), 3 deletions(-) diff --git a/kexec/arch/ppc/crashdump-powerpc.c b/kexec/arch/ppc/crashdump-powerpc.c index 4c8c75d..7313660 100644 --- a/kexec/arch/ppc/crashdump-powerpc.c +++ b/kexec/arch/ppc/crashdump-powerpc.c @@ -132,8 +132,9 @@ static int get_crash_memory_ranges(struct memory_range **range, int *ranges) goto err; } n = read_memory_region_limits(fd, &start, &end); + /* We are done with fd, close it. */ + close(fd); if (n != 0) { - close(fd); closedir(dmem); closedir(dir); goto err; @@ -153,8 +154,16 @@ static int get_crash_memory_ranges(struct memory_range **range, int *ranges) cstart = crash_base; cend = crash_base + crash_size; /* - * Exclude the region that lies within crashkernel + * Exclude the region that lies within crashkernel. + * If memory limit is set then exclude memory region + * above it. */ + if (memory_limit) { + if (start > memory_limit) + continue; + if (end > memory_limit) + end = memory_limit; + } if (cstart < end && cend > start) { if (start < cstart && end > cend) { crash_memory_range[memory_ranges].start @@ -195,7 +204,6 @@ static int get_crash_memory_ranges(struct memory_range **range, int *ranges) = RANGE_RAM; memory_ranges++; } - close(fd); } closedir(dmem); } diff --git a/kexec/arch/ppc/crashdump-powerpc.h b/kexec/arch/ppc/crashdump-powerpc.h index a377146..84a73aa 100644 --- a/kexec/arch/ppc/crashdump-powerpc.h +++ b/kexec/arch/ppc/crashdump-powerpc.h @@ -42,5 +42,6 @@ extern unsigned long long crash_base; extern unsigned long long crash_size; extern unsigned int rtas_base; extern unsigned int rtas_size; +extern uint64_t memory_limit; #endif /* CRASHDUMP_POWERPC_H */ diff --git a/kexec/arch/ppc/kexec-ppc.c b/kexec/arch/ppc/kexec-ppc.c index 6075477..de99c6a 100644 --- a/kexec/arch/ppc/kexec-ppc.c +++ b/kexec/arch/ppc/kexec-ppc.c @@ -29,6 +29,7 @@ unsigned long dt_address_cells = 0, dt_size_cells = 0; uint64_t rmo_top; +uint64_t memory_limit = 0; unsigned long long crash_base = 0, crash_size = 0; unsigned long long initrd_base = 0, initrd_size = 0; unsigned long long ramdisk_base = 0, ramdisk_size = 0; @@ -384,6 +385,41 @@ static int get_base_ranges(void) return 0; } +static int read_kernel_memory_limit(char *fname, char *buf) +{ + FILE *file; + int n; + + if (!fname || !buf) + return -1; + + if ((file = fopen(fname, "r")) == NULL) { + if (errno != ENOENT) { + perror(fname); + return -1; + } + errno = 0; + /* + * fall through. On older kernel this file + * is not present. + */ + } + else { + /* Memory limit property is of u64 type. */ + if ((n = fread(&memory_limit, 1, sizeof(uint64_t), file)) < 0) { + perror(fname); + return -1; + } + if (n != sizeof(uint64_t)) { + fprintf(stderr, "%s node has invalid size: %d\n", + fname, n); + return -1; + } + fclose(file); + } + return 0; +} + /* Get devtree details and create exclude_range array * Also create usablemem_ranges for KEXEC_ON_CRASH */ @@ -511,6 +547,18 @@ static int get_devtree_details(unsigned long kexec_flags) add_usable_mem_rgns(crash_base, crash_size); #endif } + /* + * Read the first kernel's memory limit. + * If the first kernel is booted with mem= option then + * it would export "linux,memory-limit" file + * reflecting value for the same. + */ + memset(fname, 0, sizeof(fname)); + sprintf(fname, "%s%s%s", device_tree, dentry->d_name, + "/linux,memory-limit"); + if (read_kernel_memory_limit(fname, buf) < 0) + goto error_opencdir; + /* reserve the initrd_start and end locations. */ memset(fname, 0, sizeof(fname)); sprintf(fname, "%s%s%s",
