linux-kernel - Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add

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Message-Id: <1923446.CtvhM7vr7E@hactar>
Date:	Fri, 01 Jul 2016 17:31:23 -0300
From:	Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
To:	Dave Young <dyoung@...hat.com>
Cc:	kexec@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org,
	Eric Biederman <ebiederm@...ssion.com>
Subject: Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

Am Freitag, 01 Juli 2016, 17:02:23 schrieb Thiago Jung Bauermann:
> Am Freitag, 01 Juli 2016, 14:36:02 schrieb Dave Young:
> > On 07/01/16 at 02:51pm, Thiago Jung Bauermann wrote:
> > > Am Donnerstag, 30 Juni 2016, 17:43:57 schrieb Dave Young:
> > > > On 06/30/16 at 01:42pm, Thiago Jung Bauermann wrote:
> > > > > Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> > > I understand that this is all somewhat subjective, so if you still
> > > disagree with my points I can provide a patch set implementing the
> > > change above.
> > 
> > I still feel it should be changed if more callbacks being introduced,
> > though you can regard it is internal api, like above comment we do not
> > need to assign them seperately, the member values can be assigned
> > from the beginning.
> 
> Ok, I'll implement the changes and submit a v4. Thanks for your review.

Sorry for creating more email traffic, but it'll be better if I ask this 
before I change all other places in the code. Is the code below what you
have in mind?

In particular, this version doesn't do the memset(&buf, 0, sizeof(buf))
that the previous code I sent earlier did. Is that ok?

@@ -643,13 +632,14 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 				  unsigned long max, int top_down)
 {
 	struct purgatory_info *pi = &image->purgatory_info;
-	unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
-	unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
+	unsigned long align, bss_align, bss_sz, bss_pad;
+	unsigned long entry, load_addr, curr_load_addr, bss_addr, offset;
 	unsigned char *buf_addr, *src;
 	int i, ret = 0, entry_sidx = -1;
 	const Elf_Shdr *sechdrs_c;
 	Elf_Shdr *sechdrs = NULL;
-	void *purgatory_buf = NULL;
+	struct kexec_buf buf = { .image = image, .buf_min = min,
+				.buf_max = max, .top_down = top_down };
 
 	/*
 	 * sechdrs_c points to section headers in purgatory and are read
@@ -715,9 +705,9 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 	}
 
 	/* Determine how much memory is needed to load relocatable object. */
-	buf_align = 1;
+	buf.buf_align = 1;
 	bss_align = 1;
-	buf_sz = 0;
+	buf.bufsz = 0;
 	bss_sz = 0;
 
 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
@@ -726,10 +716,10 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 
 		align = sechdrs[i].sh_addralign;
 		if (sechdrs[i].sh_type != SHT_NOBITS) {
-			if (buf_align < align)
-				buf_align = align;
-			buf_sz = ALIGN(buf_sz, align);
-			buf_sz += sechdrs[i].sh_size;
+			if (buf.buf_align < align)
+				buf.buf_align = align;
+			buf.bufsz = ALIGN(buf.bufsz, align);
+			buf.bufsz += sechdrs[i].sh_size;
 		} else {
 			/* bss section */
 			if (bss_align < align)
@@ -741,32 +731,31 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 
 	/* Determine the bss padding required to align bss properly */
 	bss_pad = 0;
-	if (buf_sz & (bss_align - 1))
-		bss_pad = bss_align - (buf_sz & (bss_align - 1));
+	if (buf.bufsz & (bss_align - 1))
+		bss_pad = bss_align - (buf.bufsz & (bss_align - 1));
 
-	memsz = buf_sz + bss_pad + bss_sz;
+	buf.memsz = buf.bufsz + bss_pad + bss_sz;
 
 	/* Allocate buffer for purgatory */
-	purgatory_buf = vzalloc(buf_sz);
-	if (!purgatory_buf) {
+	buf.buffer = vzalloc(buf.bufsz);
+	if (!buf.buffer) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
-	if (buf_align < bss_align)
-		buf_align = bss_align;
+	if (buf.buf_align < bss_align)
+		buf.buf_align = bss_align;
 
 	/* Add buffer to segment list */
-	ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
-				buf_align, min, max, top_down,
-				&pi->purgatory_load_addr);
+	ret = kexec_add_buffer(&buf);
 	if (ret)
 		goto out;
+	pi->purgatory_load_addr = buf.mem;
 
 	/* Load SHF_ALLOC sections */
-	buf_addr = purgatory_buf;
+	buf_addr = buf.buffer;
 	load_addr = curr_load_addr = pi->purgatory_load_addr;
-	bss_addr = load_addr + buf_sz + bss_pad;
+	bss_addr = load_addr + buf.bufsz + bss_pad;
 
 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
@@ -812,11 +801,11 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 	 * Used later to identify which section is purgatory and skip it
 	 * from checksumming.
 	 */
-	pi->purgatory_buf = purgatory_buf;
+	pi->purgatory_buf = buf.buffer;
 	return ret;
 out:
 	vfree(sechdrs);
-	vfree(purgatory_buf);
+	vfree(buf.buffer);
 	return ret;
 }
 

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center