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powerpc/module_64: Simplify check for -mprofile-kernel ftrace relocations

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For -mprofile-kernel, we need special handling when generating stubs for
ftrace calls such as _mcount(). To faciliate this, we check if a
R_PPC64_REL24 relocation is for a symbol named "_mcount()" along with
also checking the instruction sequence. The latter is not really
required since "_mcount()" is an exported symbol and kernel modules
cannot use it. As such, drop the additional checking and simplify the
code. This helps unify stub creation for ftrace stubs with
-mprofile-kernel and aids in code reuse.

Also rename is_mprofile_mcount_callsite() to is_mprofile_ftrace_call()
to reflect the checking being done.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7d9c316adfa1fb787ad268bb4691e7e4059ff2d5.1587488954.git.naveen.n.rao@linux.vnet.ibm.com
This commit is contained in:
Naveen N. Rao 2020-04-21 23:05:44 +05:30 committed by Michael Ellerman
parent 03b51416e8
commit 1f2aaed2db
1 changed files with 4 additions and 14 deletions
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18
arch/powerpc/kernel/module_64.c
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@ -400,19 +400,9 @@ static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
}
#ifdef CONFIG_MPROFILE_KERNEL
static bool is_mprofile_mcount_callsite(const char *name, u32 *instruction)
static bool is_mprofile_ftrace_call(const char *name)
{
if (strcmp("_mcount", name))
return false;
/*
* Check if this is one of the -mprofile-kernel sequences.
*/
if (instruction[-1] == PPC_INST_STD_LR &&
instruction[-2] == PPC_INST_MFLR)
return true;
if (instruction[-1] == PPC_INST_MFLR)
if (!strcmp("_mcount", name))
return true;
return false;
@ -436,7 +426,7 @@ static void squash_toc_save_inst(const char *name, unsigned long addr)
#else
static void squash_toc_save_inst(const char *name, unsigned long addr) { }
static bool is_mprofile_mcount_callsite(const char *name, u32 *instruction)
static bool is_mprofile_ftrace_call(const char *name)
{
return false;
}
@ -448,7 +438,7 @@ static int restore_r2(const char *name, u32 *instruction, struct module *me)
{
u32 *prev_insn = instruction - 1;
if (is_mprofile_mcount_callsite(name, prev_insn))
if (is_mprofile_ftrace_call(name))
return 1;
/*