Messages in this thread Patch in this message | | | Subject | Re: [PATCH v7 1/4] powerpc/fadump: reduce memory consumption for capture kernel | From | Hari Bathini <> | Date | Fri, 18 Aug 2017 19:30:16 +0530 |
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On Friday 18 August 2017 05:27 PM, Michal Suchánek wrote: > On Fri, 18 Aug 2017 16:20:53 +0530 > Hari Bathini <hbathini@linux.vnet.ibm.com> wrote: > >> Hi Michal, >> >> >> Thanks for the patches. I tried testing with the patches: >> >> [ 0.000000] fadump: Firmware-assisted dump is active. >> [ 0.000000] fadump: Modifying command line to enforce the >> additional parameters passed through 'fadump_extra_args=' >> [ 0.000000] fadump: Original command line: >> BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root >> ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M >> "fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2" >> rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap >> [ 0.000000] fadump: Modified command line: >> BOOT_IMAGE=/vmlinux-4.13.0-rc1-bz155783+ root=/dev/mapper/rhel-root >> ro crashkernel=2048M fadump=on fadump_reserve_mem=1024M >> "fadump_extra_args nr_cpus=1 numa=off udev.childern-max=2" >> rd.lvm.lv=rhel/root rd.lvm.lv=rhel/swap >> >> Looks like the quotes are retained not enforcing the parameters... > Hello, > > You are passing an argument >>"fadump_extra_args<< - that is an > argument containing a quote in the name. I did not test this scenario
Actually, this was not intentional.. I passed fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2" through grub loader but chosen/bootargs ended up having "fadump_extra_args=nr_cpus=1 numa=off udev.childern-max=2". Need to check why that is..
Thanks Hari
> assuming the argument name would not match in this case. It would > probably not match if the quote was in the middle of the argument > name but at the start it is skipped. Note that due to the requirement > to remove quotes symmetrically which is added in the third patch this > case does not break the commandline - it merely makes the arguments > ineffective. > > The format suggested in the documentation is >>> fadump_extra_args="nr_cpus=1 numa=off udev.childern-max=2"<< - that > is quotes around the value. This format worked in my testing. > > Unfortunately, the format with quote before argument name would > probably require another extra parameter to the callback to detect > properly. > > Thanks > > Michal > >> I am yet to test the patches in other scenarios though.. >> >> >> Thanks >> >> Hari >> >> >> On Friday 18 August 2017 01:44 AM, Michal Suchanek wrote: >>> From: Hari Bathini <hbathini@linux.vnet.ibm.com> >>> >>> With fadump (dump capture) kernel booting like a regular kernel, it >>> needs almost the same amount of memory to boot as the production >>> kernel, which is unwarranted for a dump capture kernel. But with no >>> option to disable some of the unnecessary subsystems in fadump >>> kernel, that much memory is wasted on fadump, depriving the >>> production kernel of that memory. >>> >>> Introduce kernel parameter 'fadump_extra_args=' that would take >>> regular parameters as a space separated quoted string, to be >>> enforced when fadump is active. This 'fadump_extra_args=' parameter >>> can be leveraged to pass parameters like nr_cpus=1, >>> cgroup_disable=memory and numa=off, to disable unwarranted >>> resources/subsystems. >>> >>> Also, ensure the log "Firmware-assisted dump is active" is printed >>> early in the boot process to put the subsequent fadump messages in >>> context. >>> >>> Suggested-by: Michael Ellerman <mpe@ellerman.id.au> >>> Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com> >>> Signed-off-by: Michal Suchanek <msuchanek@suse.de> >>> --- >>> Changes from v6: >>> Correct and simplify quote handling. Ideally I would like to extend >>> parse_args to give the length of the original quoted value to >>> callback. However, parse_args removes at most one doubel-quote from >>> the start and one from the end so that is easy to detect. Otherwise >>> all other users will have to be updated to trash the new argument. >>> --- >>> arch/powerpc/include/asm/fadump.h | 2 + >>> arch/powerpc/kernel/fadump.c | 109 >>> ++++++++++++++++++++++++++++++++++++-- >>> arch/powerpc/kernel/prom.c | 7 +++ 3 files changed, 115 >>> insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/powerpc/include/asm/fadump.h >>> b/arch/powerpc/include/asm/fadump.h index >>> ce88bbe1d809..98ae00943fb3 100644 --- >>> a/arch/powerpc/include/asm/fadump.h +++ >>> b/arch/powerpc/include/asm/fadump.h @@ -208,11 +208,13 @@ extern >>> int early_init_dt_scan_fw_dump(unsigned long node, const char >>> *uname, int depth, void *data); extern int fadump_reserve_mem(void); >>> extern int setup_fadump(void); >>> +extern void enforce_fadump_extra_args(char *cmdline); >>> extern int is_fadump_active(void); >>> extern void crash_fadump(struct pt_regs *, const char *); >>> extern void fadump_cleanup(void); >>> >>> #else /* CONFIG_FA_DUMP */ >>> +static inline void enforce_fadump_extra_args(char *cmdline) { } >>> static inline int is_fadump_active(void) { return 0; } >>> static inline void crash_fadump(struct pt_regs *regs, const char >>> *str) { } #endif >>> diff --git a/arch/powerpc/kernel/fadump.c >>> b/arch/powerpc/kernel/fadump.c index dc0c49cfd90a..a1614d9b8a21 >>> 100644 --- a/arch/powerpc/kernel/fadump.c >>> +++ b/arch/powerpc/kernel/fadump.c >>> @@ -78,8 +78,10 @@ int __init early_init_dt_scan_fw_dump(unsigned >>> long node, >>> * dump data waiting for us. >>> */ >>> fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", >>> NULL); >>> - if (fdm_active) >>> + if (fdm_active) { >>> + pr_info("Firmware-assisted dump is active.\n"); >>> fw_dump.dump_active = 1; >>> + } >>> >>> /* Get the sizes required to store dump data for the >>> firmware provided >>> * dump sections. >>> @@ -332,8 +334,11 @@ int __init fadump_reserve_mem(void) >>> { >>> unsigned long base, size, memory_boundary; >>> >>> - if (!fw_dump.fadump_enabled) >>> + if (!fw_dump.fadump_enabled) { >>> + if (fw_dump.dump_active) >>> + pr_warn("Firmware-assisted dump was active >>> but kernel booted with fadump disabled!\n"); return 0; >>> + } >>> >>> if (!fw_dump.fadump_supported) { >>> printk(KERN_INFO "Firmware-assisted dump is not >>> supported on" @@ -373,7 +378,6 @@ int __init >>> fadump_reserve_mem(void) memory_boundary = memblock_end_of_DRAM(); >>> >>> if (fw_dump.dump_active) { >>> - printk(KERN_INFO "Firmware-assisted dump is >>> active.\n"); /* >>> * If last boot has crashed then reserve all the >>> memory >>> * above boot_memory_size so that we don't touch >>> it until @@ -460,6 +464,105 @@ static int __init >>> early_fadump_reserve_mem(char *p) } >>> early_param("fadump_reserve_mem", early_fadump_reserve_mem); >>> >>> +#define FADUMP_EXTRA_ARGS_PARAM "fadump_extra_args=" >>> +#define FADUMP_EXTRA_ARGS_LEN >>> (strlen(FADUMP_EXTRA_ARGS_PARAM) - 1) + >>> +struct param_info { >>> + char *cmdline; >>> + char *tmp_cmdline; >>> + int shortening; >>> +}; >>> + >>> +static void __init fadump_update_params(struct param_info >>> *param_info, >>> + char *param, char *val) >>> +{ >>> + ptrdiff_t param_offset = param - param_info->tmp_cmdline; >>> + size_t vallen = val ? strlen(val) : 0; >>> + char *tgt = param_info->cmdline + param_offset + >>> + FADUMP_EXTRA_ARGS_LEN - param_info->shortening; >>> + int shortening = 0; >>> + >>> + if (!val) >>> + return; >>> + >>> + /* remove '=' */ >>> + *tgt++ = ' '; >>> + >>> + /* next_arg removes one leading and one trailing '"' */ >>> + if (*tgt == '"') >>> + shortening += 1; >>> + if (*(tgt + vallen + shortening) == '"') >>> + shortening += 1; >>> + >>> + /* remove one leading and one trailing quote if both are >>> present */ >>> + if ((val[0] == '"') && (val[vallen - 1] == '"')) { >>> + shortening += 2; >>> + vallen -= 2; >>> + val++; >>> + } >>> + >>> + /* some characters were removed - move the trailing part >>> of cmdline */ >>> + if (shortening) { >>> + char *src; >>> + >>> + strncpy(tgt, val, vallen); >>> + tgt += vallen; >>> + src = tgt + shortening; >>> + memmove(tgt, src, strlen(src) + 1); >>> + } >>> + >>> + param_info->shortening += shortening; >>> +} >>> + >>> +/* >>> + * Reworks command line parameters and splits 'fadump_extra_args=' >>> param >>> + * to enforce the parameters passed through it >>> + */ >>> +static int __init fadump_rework_cmdline_params(char *param, char >>> *val, >>> + const char *unused, >>> void *arg) +{ >>> + struct param_info *param_info = (struct param_info *)arg; >>> + >>> + if (strncmp(param, FADUMP_EXTRA_ARGS_PARAM, >>> + strlen(FADUMP_EXTRA_ARGS_PARAM) - 1)) >>> + return 0; >>> + >>> + fadump_update_params(param_info, param, val); >>> + >>> + return 0; >>> +} >>> + >>> +/* >>> + * Replace every occurrence of 'fadump_extra_args="param1 param2 >>> param3"' >>> + * in cmdline with 'fadump_extra_args param1 param2 param3' by >>> stripping >>> + * off '=' and quotes, if any. This ensures that the additional >>> parameters >>> + * passed with 'fadump_extra_args=' are enforced. >>> + */ >>> +void __init enforce_fadump_extra_args(char *cmdline) >>> +{ >>> + static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; >>> + static char init_cmdline[COMMAND_LINE_SIZE] __initdata; >>> + struct param_info param_info; >>> + >>> + if (strstr(cmdline, FADUMP_EXTRA_ARGS_PARAM) == NULL) >>> + return; >>> + >>> + pr_info("Modifying command line to enforce the additional >>> parameters passed through 'fadump_extra_args='"); + >>> + param_info.cmdline = cmdline; >>> + param_info.tmp_cmdline = tmp_cmdline; >>> + param_info.shortening = 0; >>> + >>> + strlcpy(init_cmdline, cmdline, COMMAND_LINE_SIZE); >>> + >>> + strlcpy(tmp_cmdline, cmdline, COMMAND_LINE_SIZE); >>> + parse_args("fadump params", tmp_cmdline, NULL, 0, 0, 0, >>> + ¶m_info, >>> &fadump_rework_cmdline_params); + >>> + pr_info("Original command line: %s\n", init_cmdline); >>> + pr_info("Modified command line: %s\n", cmdline); >>> +} >>> + >>> static int register_fw_dump(struct fadump_mem_struct *fdm) >>> { >>> int rc, err; >>> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c >>> index f83056297441..2e6f40217266 100644 >>> --- a/arch/powerpc/kernel/prom.c >>> +++ b/arch/powerpc/kernel/prom.c >>> @@ -693,6 +693,13 @@ void __init early_init_devtree(void *params) >>> of_scan_flat_dt(early_init_dt_scan_root, NULL); >>> of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL); >>> >>> + /* >>> + * Look for 'fadump_extra_args=' parameter and enfore the >>> additional >>> + * parameters passed to it if fadump is active. >>> + */ >>> + if (is_fadump_active()) >>> + enforce_fadump_extra_args(boot_command_line); >>> + >>> parse_early_param(); >>> >>> /* make sure we've parsed cmdline for mem= before this >>> */
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