Re: [PATCHv4 5/6] symbol lookup: introduce dereference_symbol_descriptor()
From: Petr Mladek <pmladek@suse.com>
Date: 2017-12-06 10:32:47
Also in:
lkml
On Wed 2017-12-06 13:36:49, Sergey Senozhatsky wrote:
Hello, so we got a number of build-error reports [somehow I thought 0day has compile tested the patches already; well, I was wrong] basically on congifs that have no KALLSYMS. Petr, can we replace 0006 with the following patch?
Done. See comments below.
From: Sergey Senozhatsky <redacted> Subject: [PATCH] symbol lookup: introduce dereference_symbol_descriptor() Signed-off-by: Sergey Senozhatsky <redacted>
The new patch only shuffled the code to fix a compilation problem with CONFIG_CALLSYMS undefined. It did not change the functionality. Therefore I put back: Tested-by: Tony Luck <tony.luck@intel.com> #ia64 Tested-by: Santosh Sivaraj <redacted> #powerpc Tested-by: Helge Deller <deller@gmx.de> #parisc64
quoted hunk ↗ jump to hunk
--- Documentation/printk-formats.txt | 42 ++++++++++++------------------- include/linux/kallsyms.h | 53 ++++++++++++++++++++++++++++++++++++++++ kernel/kallsyms.c | 33 ------------------------- lib/vsprintf.c | 5 ++-- 4 files changed, 71 insertions(+), 62 deletions(-)diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt index aa0a776c817a..02745028e909 100644 --- a/Documentation/printk-formats.txt +++ b/Documentation/printk-formats.txt@@ -61,41 +61,31 @@ Symbols/Function Pointers :: - %pF versatile_init+0x0/0x110 - %pf versatile_init - %pS versatile_init+0x0/0x110 - %pSR versatile_init+0x9/0x110 + %pS versatile_init+0x0/0x110 + %ps versatile_init + %pF versatile_init+0x0/0x110 + %pf versatile_init + %pSR versatile_init+0x9/0x110 (with __builtin_extract_return_addr() translation) - %ps versatile_init - %pB prev_fn_of_versatile_init+0x88/0x88 + %pB prev_fn_of_versatile_init+0x88/0x88
I was curious why so many lines were changed here. You converted the 2nd tab to spaces. I put back the tab. The result is:
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt@@ -50,42 +50,31 @@ Symbols/Function Pointers :: + %pS versatile_init+0x0/0x110 + %ps versatile_init %pF versatile_init+0x0/0x110 %pf versatile_init - %pS versatile_init+0x0/0x110 %pSR versatile_init+0x9/0x110 (with __builtin_extract_return_addr() translation) - %ps versatile_init %pB prev_fn_of_versatile_init+0x88/0x88
https://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk.git/commit/?h=for-4.16-deprecate-printk-pf&id=78675fe41d57c2bf9cb671f0a85b369a5a156f0a
quoted hunk ↗ jump to hunk
diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index bd118a6c60cb..1bcfe221e62c 100644 --- a/include/linux/kallsyms.h +++ b/include/linux/kallsyms.h +static inline void *dereference_symbol_descriptor(void *ptr) +{ +#ifdef HAVE_DEREFERENCE_FUNCTION_DESCRIPTOR + struct module *mod; + + ptr = dereference_kernel_function_descriptor(ptr); + if (is_ksym_addr((unsigned long)ptr)) + return ptr; + + preempt_disable(); + mod = __module_address((unsigned long)ptr); + preempt_enable(); + + if (mod) + ptr = dereference_module_function_descriptor(mod, ptr); +#endif + return ptr; +}
It is a bit too long for an inline function but I did not find a better solution. It should always be defined and all suitable .c files are compiled only under certain configuration. Well, it is a nop on most architectures. Best Regards, Petr